S-8540/8541 Series www.sii-ic.com STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 (c) Seiko Instruments Inc., 2000-2010 The S-8540/8541 Series is a family of CMOS step-down switching regulator controllers with PWM control (S8540 Series) and PWM/PFM switchover control (S-8541 Series). These devices consist of a reference voltage source, oscillation circuit, an error amplifier, phase compensation circuit, PWM control circuit, current limit circuit. A high efficiency and large current switching regulator is realized with the help of small external components due to the high oscillation frequency, 300 kHz and 600 kHz. The S-8540 Series provides low-ripple voltage, high efficiency, and excellent transient characteristics which come from the PMW control circuit capable of varying the duty ratio linearly from 0 to 100%, the optimized error amplifier, and the phase compensation circuit. The S-8541 Series operates under PWM control when the duty ratio is 29% or higher and operates under PFM control when the duty ratio is less than 29% to ensure high efficiency over all load range. These controllers serve as ideal main power supply units for portable devices due to the high oscillation frequencies together with the small 8-Pin MSOP package. Features * Oscillation frequency * Output voltage * Output voltage precision * Feed back type for output voltage (FB) * External components: * Built-in PWM/PFM switchover control circuit (S-8541 series) * Current limit circuit * Soft-start * Shutdown function * Lead-free, halogen-free*1 600 kHz (A, B types) 300 kHz (C, D types) 1.5 to 6.0 V, selectable in 0.1V steps (A, C types) 2.0% a transistor, a coil, a diode, and capacitors Duty ratio: 29% (PFM control) 29 to 100% (PWM control) Current is set by an external resistor RSENSE. Time is set by a capacitor CSS and a resistor RSS. *1. Refer to " Product Name Structure" for details. Applications * Power supplies for PDAs, electric organizers, and portable devices. * Power supplies for audio equipment such as portable CD players and headphone stereos. * Main or sub Power supplies for notebook computers and peripheral equipment. Package * 8-Pin MSOP Seiko Instruments Inc. 1 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Block Diagrams 1. A, C types (fixed output voltage) Pch Power MOS FET RSENSE L VIN SENSE Power for IC Triangular wave oscillation circuit 125 mV PWM comparator VIN VOUT Phase compensation circuit EXT COUT Error amplifier SD PWM or PWM / PFM switching control circuit CIN VREF=1.0 V Shutdown soft start circuit ON/OFF RSS VSS Voltage/current reference CVREF VON/OFF CVL CSS Figure 1 2. B, D types (feed back) Pch Power MOS FET RSENSE L VIN Power for IC Triangular wave oscillation circuit PWM comparator EXT VIN SENSE VOUT 125 mV Phase compensation circuit VOUT CFB RA FB RB Error amplifier SD PWM or PWM / PFM switching control circuit CIN Shutdown soft start circuit ON/OFF RSS VON/OFF VREF=1.0 V Voltage/current reference CVREF CVL CSS Figure 2 2 Seiko Instruments Inc. COUT VSS STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Product Name Structure The control types, product types, and output voltage for the S-8540/8541 series can be selected at the user's request. Please refer to the "1. Product name" for the definition of the product name, "2. Package" regarding the package drawings and "3. Product name list" for the full product names. 1. Product name S-854x x x FN - xxx T2 x Environmental code S: Lead-free, halogen-free G: Lead-free (for details, please contact our sales office) IC direction in tape specifications*1 Product name (abbreviation)*2 Package name (abbreviation) FN: 8-Pin MSOP Output voltage*3 15 to 60 (e.g. When the output voltage is 1.5 V, it is expressed as 15.) Product type A: Fixed output voltage, fosc = 600 kHz B: Feed back type, fosc = 600kHz C: Fixed output voltage, fosc = 300 kHz D: Feed back type, fosc = 300 kHz Control system 0: PWM control 1: PWM/PFM switching control *1. *2. *3. 2. Refer to the taping specifications at the end of this book. Refer to the "3. Product name list". 00: Feed back type Package Package Name 8-Pin MSOP Package FN008-A-P-SD Drawing Code Tape FN008-A-C-SD Seiko Instruments Inc. Reel FN008-A-R-SD 3 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 3. Product name list 3.1 A, B types (oscillation frequency: 600 kHz) Output Voltage (V) 1.5 1.6 1.8 2.5 3.3 5.0 Feed back (1.5 to 6.0) Table 1 S-8540xxxFN Series S-8540A15FN-IAAT2z - S-8540A18FN-IADT2z S-8540A25FN-IAKT2z S-8540A33FN-IAST2z S-8540A50FN-IBBT2z S-8540B00FN-IMAT2z S-8541xxxFN Series - S-8541A16FN-IGBT2z S-8541A18FN-IGDT2z S-8541A25FN-IGKT2z S-8541A33FN-IGST2z - S-8541B00FN-IMDT2z 3.2 C,D types (oscillation frequency: 300 kHz) Table 2 Output Voltage (V) S-8540xxxFN Series S-8541xxxFN Series 1.8 S-8540C18FN-ICDT2z S-8541C18FN-IIDT2z 2.5 S-8540C25FN-ICKT2z S-8541C25FN-IIKT2z 3.2 S-8541C32FN-IIRT2z - 3.3 S-8540C33FN-ICST2z S-8541C33FN-IIST2z Feed back (1.5 to 6.0) S-8540D00FN-IMBT2z S-8541D00FN-IMET2z Remark 1. Please consult the SII marketing department for products with an output voltage other than those specified above. 2. z: G or S 3. Please select products of environmental code = U for Sn 100%, halogen-free products. 4 Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Pin Configuration 8-Pin MSOP TOP view 1 8 2 7 3 6 4 5 Table 3 Pin Description GND pin Connection pin for external transistor IC power supply pin Bypass capacitor connection pin for CVREF reference voltage source Shutdown pin Soft-start capacitor connection pin ON/ OFF * Normal operation (step-down operation) * All circuit halts (no step-down operation) None connected (A, C types) NC*1 FB Feed back pin (B, D types) VOUT Output voltage pin SENSE Current limit detection pin The NC pin is electrically open. The NC pin can be connected to VIN and VSS. Pin No. 1 2 3 4 5 Figure 3 6 7 8 *1. Pin Name VSS EXT VIN Seiko Instruments Inc. 5 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Absolute Maximum Ratings Table 4 Item Symbol VIN pin voltage CVREF pin voltage ON/OFF pin voltage FB pin voltage*1 VOUT pin voltage SENSE pin voltage EXT pin voltage EXT pin current VIN VCVREF VON/OFF VFB VOUT VSENSE VEXT IEXT Power dissipation PD (Ta = 25 C unless otherwise specified) Absolute Maximum Ratings Unit VSS - 0.3 to VSS + 12 V VSS - 0.3 to VIN + 0.3 V VSS - 0.3 to VSS + 12 V VSS - 0.3 to VSS + 12 V VSS - 0.3 to VSS + 12 V VSS - 0.3 to VSS + 12 V VSS - 0.3 to VIN + 0.3 V 100 mA 300 (When not mounted on board) mW mW 500*2 - 40 to + 85 C - 40 to + 125 C Operating ambient temperature Topr Storage temperature Tstg *1. Feed back type (B, D types) *2. When mounted on board [Mounted board] (1) Board size : 114.3 mm x 76.2 mm x t1.6 mm (2) Board name : JEDEC STANDARD51-7 Caution (1) The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must therefore not be exceeded under any conditions. When mounted on board (2) 500 400 300 200 100 0 When not mounted on board 350 Power dissipation PD (mW) Power dissipation PD (mW) 600 0 50 100 300 250 200 150 100 50 150 Ambient temperature Ta (C) Figure 4 6 0 0 50 150 Ambient temperature Ta (C) Power Dissipation of Package Seiko Instruments Inc. 100 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Electrical Characteristics 1. S-8540/8541 Series A, C types Table 5 (Ta = 25 C, unless otherwise specified) Parameter Symbol Output voltage *1 VOUT (E) Input voltage ISS1 Current consumption during shutdown ISSS EXT pin output current Line regulation Load regulation Output voltage temperature coefficient Oscillation frequency Maximum duty ratio PWM/PFM-control switch *2 duty ratio Current limit detection voltage SENSE pin input current Shutdown pin input voltage Shutdown pin input leakage current Soft-start time Efficiency Min. - VOUT (S) x 0.980 2.5 - - VIN = VOUT (S) x 1.5 IOUT = 120 mA VIN Current consumption 1 Conditions VIN = VOUT (S) x 1.5 100 % duty ratio S-8540/8541Axx S-8540/8541Cxx MaxDuty VON/OFF = 0 V VOUT = VOUT (S) x 0.95 VIN = 10 V, VEXT = VIN - 0.2 V VIN = 10 V, VEXT = 0.2 V VOUT (S) x 1.1 VIN 10 V, IOUT = 120 mA VIN = VOUT (S) x 1.5, 10 A IOUT 150 mA VIN = VOUT (S) x 1.5, IOUT = 120 mA - 40 Ta + 85 C Measure waveform at the EXT S-8540/8541Axx pin. S-8540/8541Cxx Measure waveform at the EXT pin. PFMDuty VIN = VOUT (S) x 1.5, no load IEXTH IEXTL VOUT1 VOUT2 VOUT Ta * VOUT fOSC VSENSE ISENSE VSH VSL ISH ISL tSS EFFI External components Coil (L) Diode (SD) Output capacitor (COUT) Input capacitor (CIN) Transistor (PSW) Base resistor (Rb) Base capacitor (Cb) CVL CSS RSS RSENSE VIN = VOUT (S) x 1.5, Measure waveform at the EXT pin. VIN = VOUT (S) x 1.5, VSENSE = VIN - 0.1 V VIN = VOUT (S) x 1.5, Judge VOUT(S) x 0.98. VIN = VOUT (S) x 1.5, Judge CVREF pin "L". VIN = VOUT (S) x 1.5, VON/OFF = VOUT VIN = VOUT (S) x 1.5, VON/OFF = 0 V Time until VOUT (E) reaches 90% or higher of the VOUT(S) - Typ. Max. Units Measurement Circuit V 2 V 1 A 1 - 180 140 VOUT (S) x 1.020 10.0 300 240 - - 1.0 A 1 - 32 45 - - - 48 66 30 30 - - 60 60 1 1 2 2 - 100 - mA mA mV mV ppm/ C 510 255 100 600 300 - 690 345 - 19 29 100 6.7 2.3 - - 0.1 - 0.1 7.0 - VOUT (S) kHz 2 2 % 2 39 % 2 125 150 mV 1 11.2 - - - - 12.0 90 16.8 - 0.3 0.1 0.1 17.0 - A V V A A ms % 1 2 1 1 1 2 2 :Sumida Corporation. CDRH6D28-100 :Matsushita Electric Inducstrial Co., Ltd. MA2Q737 (Schottky diode) :Nichicon Corporation F93 (16 V, 47 F, tantalum) :Nichicon Corporation F93 (16 V, 47 F, tantalum) :Toshiba Corporation 2SA1213 :100 m :2200 pF :1.0 F :0.047 F :220 k :100 m Condition: Recommended parts are used unless otherwise specified. VIN =VOUT (S) x1.5 V, IOUT = 120 mA (When VOUT (S) 1.6 V, then VIN = 2.5 V) *1. VOUT (S) : Specified output voltage value, *2. Applied to the S-8541 series only VOUT (E) : Actual output voltage value Caution 1. Line regulation and load regulation may change greatly due to GND wiring when VIN is high. 2. In the S-8540 series (PWM control), a state in which the duty ratio 0% continues for several clocks may occur when the input voltage is high and the output current is low. In this case, the operation changes to the pseudo PFM mode, but the ripple voltage hardly increases. Seiko Instruments Inc. 7 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. S-8540/8541 Series B, D types Table 6 Parameter Output voltage *1, *2 Symbol VOUT (E) MaxDuty PFM Duty VIN = VOUT (S) x 1.5 V, no load 19 29 39 % 4 VSENSE VIN = 4.5 V, Measure waveform at the EXT pin. 100 125 150 mV 3 ISENSE VSH VSL ISH ISL VIN = 4.5 V, VSENSE = VIN - 0.1 V VIN = 4.5 V, Judge VOUT (S) x 0.98. VIN = 4.5 V, Judge CVREF pin "L". VIN = 4.5 V, VON/OFF = VOUT VIN = 4.5 V, VON/OFF = 0 V Time until VOUT (E) reaches 90% or higher of the VOUT (S) - 6.7 2.3 - - 0.1 - 0.1 11.2 - - - - 16.8 - 0.3 0.1 0.1 A V V A A 3 4 3 3 3 7.0 12.0 17.0 ms 4 - 90 - % 4 VIN Current consumption 1 ISS1 Current consumption during shutdown ISSS Line regulation Load regulation Output voltage temperature coefficient Oscillation frequency Maximum duty ratio PWM/PFM-control switch duty ratio *3 Current limit detection voltage SENSE pin input current Shutdown pin input voltage Shutdown pin input leakage current Soft-start time Efficiency External components: VIN = 4.5 V IOUT = 120 mA - S-8540/8541B00 VIN = 4.5 V 100% duty ratio S-8540/8541D00 VON/OFF = 0 V VOUT = VOUT (S) x 0.95 VIN = 10 V, VEXT = VIN - 0.2 V VIN = 10 V, VEXT = 0.2 V 3.3 VIN 10 V, IOUT = 120 mA 10 A IOUT 150 mA VIN = VOUT (S) x 1.5, IOUT = 120 mA - 40 Ta + 85C Measure waveform at S-8540/8541B00 the EXT pin. S-8540/8541D00 Measure waveform at the EXT pin. Input voltage EXT pin output current Conditions (Ta = 25 C,unless otherwise specified) MeasureMin. Typ. Max. Units ment Circuit VOUT (S) VOUT (S) VOUT (S) V 4 x 0.980 = 3.000 x 1.020 2.5 10.0 V 3 - 180 300 - 3 A 140 240 - IEXTH IEXTL VOUT1 VOUT2 VOUT Ta * VOUT fOSC tSS EFFI - - 1.0 A 3 - 32 45 - - - 48 66 30 30 - - 60 60 3 3 4 4 - 100 - mA mA mV mV ppm/ C 510 255 100 600 300 - 690 345 - kHz 4 % 4 4 Coil (L) :Sumida Corporation CDRH6D28-100 Diode (SD) :Matsushita Electric Inducstrial Co., Ltd. MA2Q737 (Schottky diode) Output capacitor (COUT) :Nichicon Corporation F93 (16 V, 47 F, tantalum) Input capacitor (CIN) :Nichicon Corporation F93 (16 V, 47 F, tantalum) :Toshiba Corporation 2SA1213 Transistor (PSW) Base resistor (Rb) :100 m :2200 pF Base capacitor (Cb) CVL :1.0 F CSS :0.047 F RSS :220 k RSENSE :100 m RA :200 k RB :100 k :50 pF CFB Condition: Connect recommended parts unless otherwise specified. VIN =4.5 V, IOUT =120 mA *1. VOUT (S) : Specified output voltage value, VOUT (E) : Actual output voltage value *2. The typical value (specified output voltage value) is VOUT (S) = 1 + RA/RB = 3.0 V. See "Output Voltage adjustment". *3. S-8541 series only Caution 1. Line regulation and load regulation may change greatly due to GND wiring when VIN is high. 2. In the S-8540 series (PWM control), a state in which the duty ratio 0% continues for several clocks may occur when the input voltage is high and the output current is low. In this case, the operation changes to the pseudo PFM mode, but the ripple voltage hardly increases. 8 Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Measurement Circuits 1. A VIN VOUT A A CVREF ON/OFF A EXT SENSE CVL CIN A VSS A Figure 5 2. RSS CSS CVREF ON/OFF RSENSE VIN VOUT + Cb VSS COUT PSW Rb EXT SENSE + CIN VON/OFF VIN CVL L SD Figure 6 3. VOUT RFB1 A VIN A FB CFB A A CVREF ON/OFF EXT SENSE RFB2 A A CVL CIN VSS Figure 7 4. RSS CFB CSS + COUT VON/OFF RFB1 VOUT FB SENSE RFB2 CVREF ON/OFF VIN EXT PSW Rb Cb + VSS CIN VIN CVL L RSENSE SD Figure 8 Seiko Instruments Inc. 9 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Operation 1. Switching control method 1. 1 PWM control (S-8540 Series) The S-8540 series consists of pulse width modulation (PWM) DC/DC converters. In conventional pulse frequency modulation (PFM) DC/DC converters, pulses are skipped when they operate at low output load current, causing the variation in the ripple frequency and the increase in the ripple voltage of the output voltage both of which constitute inherent drawbacks to those converters. In the S-8540 series the pulse width varies in the range from 0 to 100% according to the load current, yet ripple voltage produced by the switching can easily be removed by a filter since the switching frequency is always constant. These converters thus provide a low-ripple voltage over wide range of input voltage and load current. And it will be skipped to be low current consumption when the pulse width is 0% or it is no load, input current voltage is high. 1. 2 PWM/PFM switchover control (S-8541 Series) The S-8541 series is a DC-DC converter that automatically switches between a pulse width modulation method (PWM) and a pulse frequency modulation method (PFM), depending on the load current, and features low current consumption. The S-8541 series operates under PWM control with the pulse width duty changing from 29 to 100% when the output load current is high. On the other hand, when the output current is low, the S-8541 series operates under PFM control with the pulse width duty fixed at 29%, and pulses are skipped according to the load current. The oscillation circuit thus oscillates intermittently so that the resultant lower self current consumption prevents a reduction in the efficiency when the load current is low. The switching point from PWM control to PFM control depends on the external devices (coil, diode, etc.), input voltage, and output voltage. This series is an especially efficient DC-DC converter at an output current of around 100 A. 10 Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. Soft-start function The S-8540/8541 series has a built-in soft-start circuit. This circuit enables the output voltage to rise gradually over the specified soft-start time to suppress the overshooting of the output voltage and the rush current from the power source when the power is switched on or the power-off pin is set to "H" The soft-start function of this IC, however, can not suppress rush current to the load completely (Refer to Figure 9). The rush current is affected by the input voltage and the load. Please evaluate the rush current under the actual test condition. S-8540A33FN (VIN = VON / OFF = 0 5 V) 3.0 V V OU T (1 V/div) 0V 1A Rush current (0.5 A/div) 0A time (1 ms/div) Figure 9 Waveforms of output voltage and rush current at soft-start The soft-start function of the IC is achieved by raising internal reference voltage gradually, which is caused by the raising of shutdown pin voltage through RC components (RSS and CSS) connected to shutdown pin. A soft-start time (tSS) is changed by RSS, CSS and the input voltage V ON/OFF to RSS. tSS is calculated from the following formula: tSS [ms]=R [k] x C [F] x In (V ON/OFF [V] / (V ON/OFF [V] - 1.8)) e.g. When RSS = 220 k, CSS = 0.047 F, V ON/OFF = 2.7 V , then Seiko Instruments Inc. tSS = 11.4 ms. 11 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 3. ON/ OFF pin (shutdown pin) This pin deactivates or activates the step-down operation. When the ON / OFF pin is set to "L", the VIN voltage appears through the EXT pin, prodding the switching transistor to go off. All the internal circuits stop working, and substantial savings in current consumption are thus achieved. The ON / OFF pin is configured as shown in Figure 10. Since pull-up or pull-down is not performed internally, please avoid operating the pin in a floating state. Also, try to refrain from applying a voltage of 0.3 to 1.8 V to the pin, lest the current consumption increase. When this ON / OFF pin is not used, leave it coupled to the VIN pin. ON / OFF Pin "H" "L" Table 7 CR Oscillation Circuit Output Voltage Activated Deactivated Set value OPEN VIN ON/OFF VSS Figure 10 12 Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 4. Current limit circuit The S-8540/8541 series contains a current limit circuit. The current limit circuit is designed to prevent thermal destruction of external transistors due to overload or magnetic saturation of the coil. The current limit circuit can be enabled by inserting a SENSE resistor (RSENSE) between the external coil and the output pin VOUT, and connecting the node for the SENSE resistor and the coil to the SENSE pin. A current limit comparator in the IC is used to check whether the voltage between the SENSE pin and VOUT pin reaches the current limit detection voltage (VSENSE = 125 mV (typ.) ). The current flowing through the external transistor is limited by turning it off during the left time of the oscillation period after detection. The transistor is turned on again at the next clock and current limit detection resumes. If the overcurrent state still persists, the current limit circuit operates again, and the process is repeated. If the overcurrent state is eliminated, the normal operation resumes. Slight overshoot occurs in the output voltage when the overcurrent state is eliminated. Current limit setting value (ILimit) is calculated by the following formula: ILimit = Vsense ( = 125 mV) Rsense If the change with time of the current flowing through the sense resistor is higher than the response speed of the current limit comparator in the IC, the actual current limit value becomes higher than the ILimit (current limit setting value) calculated by the above formula. When the voltage difference between VIN pin and VOUT pin is large, the actual current limit value increases since the change with time of the current flowing through the sense resistor becomes large. 4. 1 VIN vs. Ipeak in the overcurrent state V IN vs. Ipeak (IC: S-8540A33FN, coil: CDRH6D28-100, RS ENSE: 100 m) 3.0 I peak (A) 2.5 2.0 1.5 1.0 1.25 A 0.5 0.0 2.5 4.0 5.5 7.0 8.5 10.0 V IN (V) Figure 11 lpeak change by input voltage When the output voltage is approximate 1.0 V or less, the load short-circuit protection does not work, since the current limit circuit does not operate. When the current limit circuit is not used, remove the SENSE resistor and connect the SENSE pin to the VSS or VOUT pin. 5. 100% duty cycle The S-8540/8541 series operates up to the maximum duty cycle of 100%. The switching transistor is kept on continuously to supply current to the load, when the input voltage falls below the preset output voltage value. The output voltage in this case is equal to the subtraction of lowering causes by DC resistance of the coil and on resistance of the switching FET from the input voltage. Even when the duty cycle is 100%, the current limit circuit works when overcurrent flows. Seiko Instruments Inc. 13 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Selection of Series Products and Associated External Components 1. Selecting a product The S-8540/8541 series is classified into eight types according to the way of control (PWM and PWM/PFM switching), the oscillation frequencies, and output voltage settings (fixed and feed back). Please select the type that suits your needs best by taking the advantage described below into account. 1. 1 Control method: Two different control methods are available: PWM control (S-8540 series) and PWM/PFM switching control (S-8541 series). 1. 2 Oscillation frequencies: The oscillation frequencies are selectable in 600 kHz (A and B types) or 300 kHz (C and D types). Because of their high oscillation frequency, the products in the A and B types allow the use of small size inductors since the peak current decreases when the same load current flows. In addition, they can also be used with small output capacitors. These outstanding features make the A and B types ideal for downsized devices. On the other hand, the C and D types, having lower oscillation frequency, are characterized by small self-consumption current and excellent efficiency under light load. 1. 3 Output voltage setting: Two different types are available: fixed output (A and C types) and feed back type (B and D types). Table 8 provides a rough guide for selecting a product depending on the requirements of the application. Choose the product that has the best score ({). Table 8 S-8540 A The set output voltage is fixed (1.5 to 6.0 V) B C D Set an output voltage freely (1.5 to 6.0 V) S-8541 { { { { { { { Use of small external parts is Important. ~ ~ ~ ~ : Indispensable condition { : Superiority of requirement ~ : Particularly superiority of requirement Seiko Instruments Inc. D Low-ripple voltage is important. Remark C { The efficiency at 100 mA or more is important. B The efficiency at light load (less than 10 mA) is important. 14 A { { { { STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. Inductor The inductance value (L) greatly affects the maximum output current (IOUT) and the efficiency (). The peak current (IPK) increases by decreasing L and the stability of the circuit improves and IOUT increases. If L is made even smaller, the efficiency falls causing a decline in the current drive capacity for the switching transistor, and IOUT decreases. The loss of IPK by the switching transistor decreases by increasing L and the efficiency becomes maximum at a certain L value. Increasing L further decreases the efficiency due to the loss of coil DC resistance. IOUT also decreases. When the inductance is large in an S-8540/8541 series product, the output voltage may grow unstable in some cases, depending on the conditions of the input voltage, output voltage, and the load current. Perform sufficient evaluation under the actual condition and decide an optimum inductance. The recommended inductances are 10 H for A, B types and 22 H for C, D types. When choosing an inductor, attention to its allowable current should be paid since the current over the allowable value will cause magnetic saturation in the inductor, leading to a marked decline in efficiency. An inductor should therefore be selected so as not IPK to surpass its allowable current. The peak current (IPK) is represented by the following equation in non-continuous operation mode: IPK = IOUT + VOUT x (VIN - VOUT) 2 x fOSC x L x VIN Where fOSC is the oscillation frequency. 3. Diode The diode to be externally coupled to the IC should be a type that meets the following conditions: * The forward voltage is low (Schottky barrier diode recommended). * The switching speed is high (50 ns max.). * The reverse direction voltage is higher than VIN. * The current rating is larger than IPK. 4. Capacitors 4. 1 Capacitors (CIN, COUT) The capacitor inserted in the input side (CIN) serves to reduce the power impedance and to average the input current for better efficiency. The CIN value should be selected according to the impedance of the power supply. It should be 47 to 100 F, although the actual value depends on the impedance of the power source used and load current value. For the output side capacitor (COUT), select a large capacitance with low ESR (Equivalent Series Resistance) to smoothen the ripple voltage. When the input voltage is extremely high or the load current is extremely large, the output voltage may become unstable. In this case the unstable area will become narrow by selecting a large capacitance for an output side capacitor. A tantalum electrolytic capacitor is recommended since the unstable area widens when a capacitor with a large ESR, such as an aluminum electrolytic capacitor, or a capacitor with a small ESR, such as a ceramic capacitor, is chosen. The range of the capacitance should generally be 47 to 100 F. 4. 2 Internal power source stabilization capacitor (CVL) The main circuits of the IC work on an internal power source connected to the CVREF pin. The CVL is a bypass capacitor for stabilizing the internal Power source. CVL should be a 1 F ceramic capacitor and wired in a short distance and at a low impedance. Seiko Instruments Inc. 15 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 5. External transistor The S-8540/8541 series can work with an enhancement (Pch) MOS FET or a bipolar (PNP) transistor as an external transistor. 5. 1 Enhancement (Pch) MOS FET The EXT pin can directly drive the Pch MOS FET with a gate capacity of approximate 1200 pF. When a Pch MOS FET is chosen, efficiency will be 2 to 3 % higher than that achieved by a PNP bipolar transistor since the MOS FET switching speed is faster than that of the bipolar transistor and power loss due to the base current is avoided. The important parameters in selecting a Pch MOS FET are the threshold voltage, breakdown voltage between gate and source, breakdown voltage between drain and source, total gate capacity, onresistance, and the current ratings. The EXT pin swings from voltage VIN to VSS. When the input voltage is low, a MOS FET with a low threshold voltage has to be used so that the MOS FET will turn on as required. When, conversely, the input voltage is high, select a MOS FET whose gate-source breakdown voltage is higher than the input voltage by at least several volts. Immediately after the power is turned on, or the power is turned off (that is, when the step-down operation is terminated), the input voltage is applied across the drain and the source of the MOS FET. The transistor therefore needs to have drain-source breakdown voltage that is also several volts higher than the input voltage. The total gate capacity and the on-resistance affect the efficiency. The power loss for charging and discharging the gate capacity by switching operation will affect the efficiency at low load current region more when the total gate capacity becomes larger and the input voltage becomes higher. If the efficiency at low load is a matter of concern, select a MOS FET with a small total gate capacity. In regions where the load current is high, the efficiency is affected by power loss caused by the onresistance of the MOS FET. If the efficiency under heavy load is particularly important in the application, choose a MOS FET having on-resistance as low as possible. As for the current rating, select a MOS FET whose maximum continuous drain current rating is higher than IPK. 16 Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 5. 2 Bipolar (PNP) transistor Figure 12 shows a circuit diagram using Toshiba Corporation 2SA1213-Y for the bipolar transistor (PNP). Using a bipolar transistor, the driving capacity for increasing the output current is determined by the hFE value and the Rb value. 2SA1213-Y VIN Rb VIN Cb EXT Figure 12 The Rb value is given by the following equation: Rb = VIN - 0.7 Ib - 0.4 IEXTL Calculate the necessary base current Ib using the hFE value of the bipolar transistor from the relation, Ib = IPK/hFE, and select a smaller value for Rb which is calculated from the above equation. A small Rb value will certainly contribute to increase the output current, but it will also decrease the efficiency. Determine the optimum value through experiment since the base current flows as pulses and voltage drop may takes place due to the wiring resistance and so on. In addition, if speed-up capacitor Cb is inserted in parallel with resistance Rb, as shown in Figure 12, the switching loss will be reduced, leading to a higher efficiency. by using the following equation : Cb 1 2 x Rb x fOSC x 0.7 Select a Cb value after performing sufficient evaluation since the optimum Cb value differs depending upon the characteristics of the bipolar transistor. Seiko Instruments Inc. 17 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Standard Circuits 1. Fixed output voltage (Pch MOS FET) RSENSE L SENSE Tr VIN Power for IC Triangular wave oscillation circuit PWM comparator - + EXT + - Phase compensation circuit VOUT Error amplifier SD VIN 125mV COUT - + PWM, PWM/PFM switching control circuit CIN VREF=1.0 V Voltage/current reference Shutdown soft start circuit ON/OFF VSS CVREF VON/OFF One point ground Figure 13 2. Feed back type (Pch MOS FET) RSENSE L Tr VIN + oscillation circuit PWM comparator EXT - + - Phase compensation circuit 125mV Error amplifier SD VIN SENSE Power for IC Triangular wave PWM, PWM/PFM switching control circuit CIN Shutdown soft start ON/OFF RA COUT + FB Voltage/current reference VON/OFF CFB - VREF=1.0 V circuit VOUT VSS RB CVREF One point ground Figure 14 Caution 18 The above connection diagram and constant will not guarantees successful operation. Perform through evaluation using the actual application to set the constant. Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Precautions y Install the external capacitors, diode, coil, and other peripheral components as close to the IC as possible, and make a one-point grounding. When the input voltage is 9 to 10 V, VOUT may vary largely according to the grounding method. When it is difficult to make one-point grounding, use two grounds: one for VIN, CIN, and SD GND, and the other for VOUT, VCVREF, and IC GND. y Characteristics ripple voltage and spike noise occur in IC containing switching regulators. Moreover rush current flows at the time of a power supply injection. Because these largely depend on the inductor, the capacitor and impedance of power supply used, fully check them using an actually mounted model. y If the input voltage is high and output current is low, pulses with a low duty ratio may appear, and then the 0% duty ratio continues for several clocks. In this case the operation changes to the pseudo pulse frequency modulation (PFM) mode, but the ripple voltage hardly increases. y If the input power supply voltage is lower than 1.0 V, the IC operation is unstable and the external switch may be turned on. If input power supply voltage is 10.0 V or higher, the circuit operation is unstable and the IC may be damaged. The input voltage must be in the standard range (2.5 to 10.0 V). y The current limit circuit of the IC limits current by detecting a voltage difference of external resistor RSENSE. In choosing the components, make sure that overcurrent will not surpass the allowable dissipation of the switching transistor and the inductor. y Make sure that dissipation of the switching transistor will not surpass the allowable power dissipation of the package (especially at high temperature). y Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in electrostatic protection circuit. y Seiko Instruments Inc. shall bear no responsibility for any patent infringement by a product that includes an IC manufactured by Seiko Instruments Inc. in relation to the method of using the IC in that product, the product specifications, or the destination country. Seiko Instruments Inc. 19 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Application Circuits 1. External adjustment of output voltage The output voltage can be adjusted or changed in the output voltage setting range (1.5 to 6.0 V) by adding external resistors (RA, RB) and a capacitor (CFB) in the S-8540/8541B00AFN and S8540/8541D00AFN, as shown in Figure 15. Temperature gradient can be given by inserting a thermistor in series to RA and RB. RSENSE L Tr VIN + - oscillation circuit PWM comparator EXT - + Phase compensation circuit 125mV Error amplifier SD VIN SENSE Power for IC Triangular wave PWM, PWM/PFM switching control circuit CIN Shutdown soft start circuit ON/OFF CFB RA - COUT FB + VREF=1.0 V Voltage/current reference VON/OFF VOUT VSS RB CVREF One point ground Figure 15 Caution 20 The above connection diagram and constant will not guarantees successful operation. Perform through evaluation using the actual application to set the constant. Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series RA, RB must be RA + RB 2 M and the ratio of RA to RB should be set so that the FB pin is 1.0 V. capacitor (CFB) in parallel to RA to prevent unstable operation like output oscillation. Add a Set the CFB so that f = 1/(2 x CFB x RA) is 0.1 to 20 kHz (normally 10 kHz). e.g. When VOUT = 3.0 V, RA = 200 k, RB = 100 k, then CFB = 100 pF. The precision of output voltage (VOUT) determined by RA, RB is affected by the precision of the voltage at the FB pin (1 V 2.0%), the precision of RA and RB, current input to the FB pin, and IC power supply voltage VDD. Suppose that the FB pin input current is 0 nA, and that the maximum absolute values of the external resistors RA and RB are RA max. and RB max, and the minimum absolute values of the external resistors RA and RB are RA min. and RB min., and that the output voltage shift due to the VDD voltage dependency is V, the minimum value VOUT min. and maximum value VOUT max. of the output voltage VOUT variation is calculated by the following formula: VOUTmin. = (1 + RAmin. ) x 0.98 - V [V] RBmax. RAmax. VOUTmax. = (1 + ) x 1.02 + V [V] RBmin. The precision of the output voltage VOUT cannot be made lower than the precision of the IC output voltage without adjustment of external resistors RA and RB. The lower the RA/RB, the less it is affected by the absolute value precision of the external resistors RA and RB. The lower the RA and RB, the less it is affected by the FB pin input current. To suppress the influence of FB pin input current on the variation of output voltage VOUT, the external resistor RB value must be made sufficiently lower than the input impedance of the FB pin, 1 V/50 nA = 20 M max. Waste current flows through external resistors RA and RB. When it is not a negligible value with respect to load current in actual use, the efficiency decreases. The RA and RB values of the external resistors must therefore be made sufficiently high. Evaluation of the influence of the noise is needed in the actual condition If the RA and RB values of resistors are high (1 M or higher) since they are susceptible to external noise. The output voltage VOUT precision and the waste current are in a trade-off relation. considered according to application requests. Seiko Instruments Inc. They must be 21 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Typical Characteristics 1. Examples of major parameters characteristics (1) ISS1 - VIN S-8540/8541(300 kHz) (2) ISS1 - VIN 250 250 200 25C 85C 85C 200 ISS1 (A) ISS1 (A) S-8540/8541(600 kHz) 150 150 100 100 25C Ta=-40C 50 0 0 2.5 4.0 5.5 7.0 8.5 10.0 2.5 4.0 5.5 VIN (V) (3) fOSC - VIN 7.0 8.5 10.0 8.5 10.0 VIN (V) (4) fOSC - VIN S-8540/8541(300 kHz) 360 S-8540/8541(600 kHz) 720 85C 680 fOSC (kHz) 340 fOSC (kHz) Ta=-40C 50 320 300 Ta=-40C 25C 280 85C 640 600 560 Ta=-40C 25C 520 260 480 240 2.5 4.0 5.5 7.0 8.5 2.5 10.0 4.0 VIN (V) (5) IEXTH - VIN 5.5 7.0 VIN (V) (6) IEXTL - VIN S-8540/8541 S-8540/8541 100 100 80 Ta=-40C 60 IEXTL (mA) IEXTH (mA) 80 25C 40 Ta=-40C 60 40 25C 20 20 85C 0 0 2.5 2.5 4.0 5.5 7.0 8.5 85C 4.0 5.5 7.0 8.5 10.0 VIN (V) 10.0 VIN (V) (8) VSL - VIN S-8540/8541 2.3 0.9 2.2 0.8 Ta=-40C 2.1 VSL (V) VSH (V) (7) VSH - VIN S-8540/8541 25C 2.0 1.9 1.8 Ta=-40C 0.7 0.5 85C 0.4 85C 1.7 0.3 2.5 4.0 5.5 7.0 8.5 10.0 2.5 VIN (V) 22 25C 0.6 4.0 5.5 7.0 VIN (V) Seiko Instruments Inc. 8.5 10.0 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series tSS (ms) (9) tSS - VIN 16 15 14 13 12 11 10 9 8 Ta=-40C 25C 2.5 4.0 5.5 85C 7.0 8.5 10.0 VIN (V) (10) VOUT - VIN 1.8 V (11) VOUT - VIN 3.3 V PWM/PFM 600 kHz 1.85 3.40 IOUT =0.1 mA IOUT =0.1 mA 1.81 1.79 3.30 400 mA 3.25 100 mA 1.77 400 mA 1.75 3.20 2.5 4 5.5 7 8.5 10 2.5 4.0 5.5 VIN (V) (12) VOUT - VIN 3.3 V 7.0 8.5 10.0 VIN (V) (13) VOUT - VIN 3.3 V PWM 600 kHz 3.40 PWM/PFM 300 kHz 3.40 IOUT =0.1 mA VOUT (V) 100 mA IOU T =0.1 mA 3.35 VOUT(V) 100 mA 3.35 VOUT (V) 1.83 VOUT (V) PWM/PFM 600 kHz 3.30 400 mA 3.25 100 mA 3.35 3.30 400 mA 3.25 3.20 3.20 2.5 4.0 5.5 7.0 8.5 10.0 2.5 4.0 5.5 7.0 8.5 10.0 VIN (V) VIN (V) Seiko Instruments Inc. 23 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. Transient Response Characteristics 2. 1 Power-on (IOUT: no Load) (1) S-8540A33FN (VIN: 0 4.95 V) (2) S-8540A33FN (VIN: 0 10 V) 10 V 10 V VIN (2.5 V/div) V IN (2.5 V/div) 0V 0V 3V 3V V OUT (1 V/div) 0V VOUT (1 V/div) 0V t (2 ms/div) t (1 ms/div) (3) S-8540C33FN (VIN: 0 4.95 V) (4) S-8540C33FN (VIN: 0 10 V) 10 V 10 V VIN (2.5 V/div) VIN (2.5 V/div) 0V 0V 3V 3V VOUT (1 V/div) VOU T (1 V/div) 0V 0V t (2 ms/div) t (1 ms/div) (5) S-8540A18FN (VIN: 0 2.7 V) (6) S-8540A18FN (VIN: 0 10 V) 10 V 10 V V IN (2.5 V/div) VIN (2.5 V/div) 0V 0V 2V 2V VOUT (0.5 V/div) V OUT (0.5 V/div) 0V 0V t (4 ms/div) 24 t (1 ms/div) Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. 2 Shutdown pin response (VON/OFF : 0 2.5 V (1) S-8540A33FN (VIN: 4.95V) 4V IOUT: no Load) (2) S-8540A33FN (VIN: 10V) 4V VON/OFF (1 V/div) VON/OFF (1 V/div) 0V 0V 3V 3V VOUT (1 V/div) 0V VOUT (1 V/div) 0V t (4 ms/div) t (4 ms/div) (3) S-8540C33FN (VIN: 4.95 V) (4) S-8540C33FN (VIN: 10 V) 4V 4V VON/OFF (1 V/div) 0V VON/OF F (1 V/div) 0V 3V 3V VOUT (1 V/div) VOUT (1 V/div) 0V 0V t (4 ms/div) (5) S-8540A18FN (VIN: 4.95 V) t (4 ms/div) (6) S-8540A18FN (VIN: 10 V) 4V 4V VON /OF F (1 V/div) VON /OF F (1 V/div) 0V 0V 1.5 V 1.5 V VOUT (0.5 V/div) 0V VOUT (0.5 V/div) 0V t (4 ms/div) t (4 ms/div) Seiko Instruments Inc. 25 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. 3 Supply Voltage Variation (VIN: 3.69.03.6 V) (1) S-8540A33FN (IOUT: 10 mA) (2) S-8540A33FN (IOUT: 500 mA) 10 V 10 V VIN (2.5 V/div) VIN (2.5 V/div) 0V 0V VOUT (0.1 V/div) VOUT (0.1 V/div) t (0.4 ms/div) t (0.4 ms/div) (3) S-8540C33FN (IOUT: 10 mA) (4) S-8540C33FN (IOUT: 500 mA) 10 V 10 V V IN (2.5 V/div) VIN (2.5 V/div) 0V 0V VOUT (0.1 V/div) VOUT (0.1 V/div) t (0.4 ms/div) (5) S-8540A18FN (IOUT: 10 mA) t (0.4 ms/div) (6) S-8540A18FN (IOUT: 500 mA) 10 V 10 V VIN (2.5 V/div) V IN (2.5 V/div) 0V 0V VOUT (0.1 V/div) VOUT (0.1 V/div) t (0.4 ms/div) 26 t (0.4 ms/div) Seiko Instruments Inc. STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. 4 Load Variation (VIN: 2.7 V or 5.0 V or 7.5 V, IOUT: 0.1500 mA, 5000.1 mA) (1) S-8540A33FN (VIN: 4.95 V) (2) S-8540A33FN (VIN: 4.95 V) 500 mA IOU T 500 mA 0.1 mA IOUT 0.1 mA V OUT (0.1 V/div) VOUT (0.1 V/div) t (4 ms/div) t (0.2 ms/div) (3) S-8540C33FN(VIN: 4.95 V) (4) S-8540C33FN(VIN: 4.95 V) 500 mA IOUT 500 mA IOUT 0.1 mA 0.1 mA VOUT (0.1 V/div) VOUT (0.1 V/div) t (8 ms/div) t (0.2 ms/div) (5) S-8540A18FN (VIN: 2.7 V) (6) S-8540A18FN (VIN: 2.7 V) 500 mA 500 mA IOU T IOU T 0.1 mA 0.1 mA V OUT (0.1 V/div) VOU T (0.1 V/div) t (0.2 ms/div) t (4 ms/div) Seiko Instruments Inc. 27 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Reference Data This reference data is intended to help you select peripheral components to be externally connected to the IC. Therefore, this information provides recommendations on external components selected with a view to accommodating a wide variety of IC applications. Characteristic data is duly indicated in the table below. Table 9. External components list for efficiency (Small and thin application using 1.3 mm or less tall components, maximum load current : IOUT = 0.9 A) Output Modulation fOSC No. Product Name Inductor Transistor Diode Output Capacitor Voltage 1.1 S-8540A33FN 1.2 S-8541A33FN 1.3 S-8540A25FN 3.3 V PWM PWM/PFM PWM 2.5 V 1.4 S-8541A25FN 1.5 S-8540A18FN 600kHz LDR655312T-4R7 CPH6301 RB491D F920J476MB x 2 PWM/PFM PWM 1.8 V 1.6 S-8541A18FN PWM/PFM Table 10 External components list for efficiency (High efficiency application using 3.0mm or less tall components, maximum load current : IOUT = 1.0 A) Output Modulation fOSC No. Product Name Inductor Transistor Diode Output Capacitor Voltage 1.7 S-8540C33FN 1.8 S-8541C33FN 1.9 S-8540C25FN 3.3 V PWM PWM/PFM PWM 300kHz 2.5 V 1.10 S-8541C25FN CDRH6D28-220 CPH6301 RB491D F931A476MC x 1 PWM/PFM 1.11 S-8540C18FN PWM 1.8 V 1.12 S-8541C18FN PWM/PFM Table 11 External components list for ripple voltage No. Product Name Output Modulation Voltage 2.1 S-8540A33FN 2.2 S-8541A33FN PWM/PFM 2.3 S-8540A18FN PWM 2.4 S-8541A18FN 2.5 S-8540C33FN 3.3 V fOSC Inductor Transistor Diode Output Capacitor PWM 600kHz LDR655312T-4R7 CPH6301 RB491D F920J476MB x 2 1.8 V PWM/PFM PWM 3.3 V 2.6 S-8541C33FN PWM/PFM 2.7 S-8540C18FN PWM 2.8 S-8541C18FN 300kHz CDRH6D28-220 1.8 V 28 PWM/PFM Seiko Instruments Inc. CPH6301 RB491D F931A476MC x 1 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Table 12 External parts function Component Product Name LDR655312T-4R7 Inductor CDRH6D28-220 Diode RB491D Output F920J476MB Capacity (tantalum F931A476MC electrolytic) Transistor CPH6301 (MOS FET) Manufacturer L-Value DC Resistance Maximum Current Size (L x W x H) [mm] TDK Corporation Sumida Corporation Rohm Corporation Nichicon Corporation Nichicon Corporation Sanyo Electric Co., Ltd. 4.7 H 0.19 0.9 A 6.5 x 5. 3 x 1.25 22.0 H 0.128 1.2 A 7.0 x 7.0 x 3.0 Forward current 1.0 A at VF = 0.45 V, Vrm = 25V 3.0 x 3.1 x 1.3 47 F, 6.3 V 3.6 x 3.0 x 1.2 47 F, 10.0 V 6.2 x 3.4 x 2.7 Vdss =20 V max., Vgss =10 V max., ID =3.0 A max., Ciss =360 pF, Ron =110 m 2.9 x 2.8 x 0.9 Seiko Instruments Inc. 29 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series Efficiency Characteristics : Efficiency () - Output current (IOUT) 1. 1 S-8540A33FN 100 Efficiency (%) 1. 2 S-8541A33FN (3.3 V, 600 kHz, PWM control) (3.3 V, 600 kHz, PWM/PFM control) 100 V IN=4.0 V 90 Efficiency (%) 1. 80 5.0 V 70 7.2 V 60 VIN=4.0 V 90 80 70 5.0 V 50 50 1 10 100 1000 1 10 I OUT (mA) S-8540A25FN 1. 4 Efficiency (%) (2.5 V, 600 kHz, PWM/PFMcontrol) 100 V IN=3.0 V 90 80 3.6 V 70 5.0 V 60 50 1 10 100 VIN=3.0 V 90 80 70 3.6 V 50 1000 1 10 1. 6 (1.8 V, 600 kHz, PWM control) VIN=2.5 V 80 3.6 V 5.0 V 60 50 1 10 100 1000 (1.8 V, 600 kHz, PWM/PFM control) VIN=2.5 V 90 80 70 3.6 V 5.0 V 60 50 1 10 100 IOUT (mA) I OUT (mA) 30 1000 S-8541A18FN 100 Efficiency (%) Efficiency (%) 100 70 100 IOUT (mA) S-8540A18FN 90 5.0 V 60 IOUT (mA) 1. 5 1000 S-8541A25FN (2.5 V, 600 kHz, PWM control) 100 100 IOUT (mA) Efficiency (%) 1. 3 7.2 V 60 Seiko Instruments Inc. 1000 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 1. 7 S-8540C33FN 1. 8 (3.3 V, 300 kHz, PWM control) 100 Efficiency (%) Efficiency (%) 80 5.0 V 70 7.2 V 60 50 10 100 VIN =4.0 V 90 80 70 5.0 V 7.2 V 60 50 1 (3.3 V, 300 kHz, PWM/PFM control) 100 VI N=4.0 V 90 S-8541C33FN 1000 1 10 S-8540C25FN 1. 10 (2.5 V, 300 kHz, PWM control) VIN=3.0 V 90 80 5.0 V 3.6 V 70 60 50 1 10 100 S-8541C25FN (2.5 V, 300 kHz, PWM/PFM control) 100 Efficiency (%) Efficiency (%) 100 VIN =3.0 V 90 80 5.0 V 3.6 V 70 60 50 1000 1 10 IOUT (mA) S-8540C18FN Efficiency (%) 1. 12 (1.8 V, 300 kHz, PWM control) 100 VIN =2.5 V 90 80 3.6 V 5.0 V 70 60 50 1 10 100 1000 IOUT (mA) 100 1000 S-8541C18FN (1.8 V,300 kHz, PWM/PFM control) 100 Efficiency (%) 1. 11 1000 IOUT (mA) IOUT (mA) 1. 9 100 VIN =2.5 V 90 80 3.6 V 70 5.0 V 60 50 1 IOUT (mA) 10 100 1000 IOUT (mA) Seiko Instruments Inc. 31 STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER Rev.4.0_00 S-8540/8541 Series 2. Ripple Voltage (Vrip) - Output Current (IOUT) Characteristics 2. 1 S-8540A33FN 2. 2 S-8541A33FN (3.3 V, 600 kHz, PWM control) 7.2 V Ripple (mV) 80 5.0 V V IN=4.0 V 60 (3.3 V, 600 kHz, PWM/PFM control) 100 80 Ripple (mV) 100 40 5.0 V 40 20 20 0 0 1 10 100 1000 1 10 S-8540A18FN 80 3.6 V 60 5.0 V V IN=2.5 V 40 20 (1.8 V, 600 kHz, PWM/PFM control) 80 3.6 V 60 VIN=2.5 V 20 0 1 10 100 1 1000 10 IOUT (mA) 2. 6 (3.3 V, 600 kHz, PWM control) 100 3.6 V VIN=2.5 V 5.0 V 40 (3.3 V, 600 kHz, PWM/PFM control) 100 20 0 80 60 VIN =2.5 V 20 1 10 100 0 1000 1 10 2. 8 1000 S-8541C18FN (1.8 V, 300 kHz, PWM control) 100 80 80 Ripple (mV) 100 60 3.6 V 40 100 IOUT (mA) S-8540C18FN Ripple (mV) 3.6 V 5.0 V 40 IOUT (mA) V IN=2.5 V 5.0 V 20 (1.8 V, 300 kHz, PWM/PFM control) 60 V IN=2.5 V 40 3.6 V 5.0 V 20 0 0 1 10 100 1000 1 IOUT (mA) 32 1000 S-8541C33FN Ripple (mV) Ripple (mV) 80 60 100 IOUT (mA) S-8540C33FN 2. 7 5.0 V 40 0 2. 5 1000 S-8541A18FN 100 Ripple (mV) Ripple (mV) 2. 4 (1.8 V, 600 kHz, PWM control) 100 100 IOUT (mA) IOUT (mA) 2. 3 7.2 V V IN=4.0 V 60 10 100 IOUT (mA) Seiko Instruments Inc. 1000 2.950.2 8 5 1 4 0.130.1 0.20.1 0.650.1 No. FN008-A-P-SD-1.1 TITLE MSOP8-A-PKG Dimensions No. FN008-A-P-SD-1.1 SCALE UNIT mm Seiko Instruments Inc. 2.00.05 4.00.1 1.350.15 4.00.1 1.550.05 1.050.05 0.30.05 3.10.15 4 1 5 8 Feed direction No. FN008-A-C-SD-1.1 TITLE MSOP8-A-Carrier Tape No. FN008-A-C-SD-1.1 SCALE UNIT mm Seiko Instruments Inc. 16.5max. 13.00.3 Enlarged drawing in the central part 130.2 (60) (60) No. FN008-A-R-SD-1.1 MSOP8-A-Reel TITLE FN008-A-R-SD-1.1 No. SCALE UNIT QTY. 3,000 mm Seiko Instruments Inc. www.sii-ic.com * * * * * * * The information described herein is subject to change without notice. Seiko Instruments Inc. is not responsible for any problems caused by circuits or diagrams described herein whose related industrial properties, patents, or other rights belong to third parties. The application circuit examples explain typical applications of the products, and do not guarantee the success of any specific mass-production design. When the products described herein are regulated products subject to the Wassenaar Arrangement or other agreements, they may not be exported without authorization from the appropriate governmental authority. Use of the information described herein for other purposes and/or reproduction or copying without the express permission of Seiko Instruments Inc. is strictly prohibited. The products described herein cannot be used as part of any device or equipment affecting the human body, such as exercise equipment, medical equipment, security systems, gas equipment, or any apparatus installed in airplanes and other vehicles, without prior written permission of Seiko Instruments Inc. The products described herein are not designed to be radiation-proof. Although Seiko Instruments Inc. exerts the greatest possible effort to ensure high quality and reliability, the failure or malfunction of semiconductor products may occur. The user of these products should therefore give thorough consideration to safety design, including redundancy, fire-prevention measures, and malfunction prevention, to prevent any accidents, fires, or community damage that may ensue.