03260 09/23/2010 Rev: F
EP5368QI
600mA Synchronous Buck Regulator
with Integrated Inductor
RoHS Compliant; Halogen Free
www.enpirion.com
Description
The EP5368QI is a synchronous buck converter
with integrated Inductor, PWM controller,
MOSFETS, and Compensation providing the
smallest possible solution size. The EP5368QI
requires only two small MLCC capacitors to
make a complete solution. Integration of the
inductor greatly simplifies design, contains noise,
reduces part count, and reduces solution
footprint. Low output ripple ensures compatibility
with RF systems.
The EP5368QI operates at a switching frequency
of 4 MHz, enabling this unprecedented level of
integration and small external components. Type
III voltage mode control is used to provide high
noise immunity and wide control loop bandwidth.
The device can source 600mA of current over
the industrial temperature range and up to
700mA over the commercial temperature range.
The small footprint makes this part ideal for
space constrained applications. Output voltage
is programmed via a 3-pin VID selector providing
seven pre-programmed output voltages along
with an option for external resistor divider.
Figure 1: Features INTEGRATED INDUCTOR
TECHNOLOGY
Features
• Integrated Inductor
• 3mm x 3mm x 1.1mm QFN package
• Only two low cost MLCC caps required
• 4 MHz switching frequency
• High efficiency, up to 94%
• Up to 700mA continuous output current
• Wide 2.4V to 5.5V input range
• VOUT Range 0.603V to VIN – 0.4V
• 100% duty cycle capable
• Less than 1 µA standby current
• Low VOUT ripple for RF compatibility
• Short circuit and over current protection
• UVLO and thermal protection
• Stable over entire operating range
• RoHS compliant; MSL 3 260°C reflow
Application
• Noise sensitive RF applications
• Area constrained applications
• Smart phones and PDAs
• Personal Media Players
• Advanced Mobile Processors, DSP, IO,
Memory, Video, Multimedia Engines
Figure 2: Typical Application Schematic
VIN VSense
Vin
VS1
VS2
VS0
EP5368QI 22µF
0805
4.7µF
0603
VOUT
Vout
GND
ENABLE
VFB
Voltage
Select
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 2 www.enpirion.com
Ordering Information
Part Number
Temp Rating
(°C) Package
EP5368QI -40 to +85 16-pin QFN T&R
EP5368QI-E EP5368QI Evaluation Board
Pin Assignments (Top View)
Figure 3: Pin Out Diagram (Top View)
Pin Description
PIN
NAME
FUNCTION
1, 3, 9,
15, 16 NC NO CONNECT – These pins should not be electrically connected to each other or to any
external signal, voltage, or ground. One or more of these pins may be connected internally.
These pins must be soldered to the PCB.
2 PGND Power Ground
4 VFB
Feed back pin for external divider option. When using the external divider option
(VS0=VS1=VS2= high) connect this pin to the center of the external divider. Set the divider
such that VFB = 0.6V. The “ground” side of the external divider should be connected to
AGND.
5 VSENSE Sense pin for preset output voltages. Connect this to VOUT or as close to VOUT as possible
to ensure the best regulation.
6 AGND Analog ground. This is the quiet ground for the internal control circuitry.
7, 8 VOUT Regulated Output Voltage
10, 11,
12 VS0, VS1,
VS2
Output voltage select. VS2=pin10 VS1=pin11, VS0=pin12. Selects one of seven preset
output voltages or choose external divider by connecting pins to logic high or low. Logic low
is defined as VLOW ≤ 0.4V. Logic high is defined as VHIGH ≥ 1.4V. Any level between these
two values is indeterminate. (Refer to section on output voltage select for more detail).
13 ENABLE Output enable: Enable = logic high, disable = logic low. Logic low is defined as VLOW ≤ 0.4V.
Logic high is defined as VHIGH ≥ 1.4V. Any level between these two values is indeterminate.
14 VIN Input voltage pin. Supplies power to the IC.
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 3 www.enpirion.com
Absolute Maximum Ratings
CAUTION: Absolute Maximum ratings are stress ratings only. Functional operation beyond the
recommended operating conditions is not implied. Stress beyond the absolute maximum ratings may
cause permanent damage to the device. Exposure to absolute maximum rated conditions for
extended periods may affect device reliability.
SYMBOL
MIN
MAX
UNITS
Input Supply Voltage VIN -0.3 7.0 V
Voltages on: ENABLE, VSENSE, VS0 – VS2 -0.3 VIN +0.3 V
Voltage on: VFB -0.3 2.7 V
Storage Temperature Range TSTG -65 150 °C
Reflow Temp, 10 Sec, MSL3 JEDEC J-STD-020C 260 °C
ESD Rating (based on Human Body Mode) 2000 V
Recommended Operating Conditions
SYMBOL
MIN
MAX
UNITS
Input Supply Voltage VIN 2.4 5.5 V
Operating Ambient Temperature TA - 40 85 °C
Operating Junction Temperature TJ - 40 125 °C
Thermal Characteristics
SYMBOL
TYP
UNITS
Thermal Resistance: Junction to Ambient (0 LFM) θJA 85 °C/W
Thermal Overload Trip Point TJ-TP 150 °C
Thermal Overload Trip Point Hysteresis 15 °C
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 4 www.enpirion.com
Electrical Characteristics
NOTE: TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = 25°C, V IN = 3.6V
CIN = 4.7µF 0603 MLCC, COUT = 22µF 0805 MLCC
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Operating Input Voltage
Range VIN 2.4 5.5 V
Under Voltage Lock-out –
VIN Rising VUVLO_R 2.2 2.3 V
Under Voltage Lock-out –
VIN Falling VUVLO_F 2.1 2.2 V
Drop Out Resistance RDO Input to Output Resistance in 100%
duty cycle operation. 400 500 mΩ
Output Voltage Range VOUT External Feedback Mode
VID Mode 0.603
0.8 V
IN
-V
DO
3.3 V
Dynamic Voltage Slew
Rate (VID Change) VSLEW 0.975 1.5 2.025 V/mS
VOUT Initial Accuracy (VID
Preset Mode) ∆VOUT_INITIAL
TA = 25°C, VIN = 3.6V;
ILOAD = 100mA ;
0.8V ≤ VOUT ≤ 3.3V -2 +2 %
VOUT Accuracy (VID
Preset Mode)
over line, load and
temperature variation
∆VOUT_ALL
-40°C ≤ TA ≤ +85°C
2.4V ≤ VIN ≤ 5.5V;
0.8V ≤ VOUT ≤ 3.3V
0A ≤ ILOAD ≤ 700A
-3 +3 %
Feedback Pin Voltage
Initial Accuracy ∆VFB_INITIAL TA = 25°C, VIN = 3.6V;
ILOAD = 100mA ;
0.8V ≤ VOUT ≤ 3.3V 0.591 .603 0.615 V
Feedback Pin Voltage
Accuracy over line, load,
and temperature variations ∆VFB_ALL
-40°C ≤ TA ≤ +85°C
2.4V ≤ VIN ≤ 5.5V;
0.8V ≤ VOUT ≤ 3.3V
0A ≤ ILOAD ≤ 700A
0.585 .603 0.621 V
Feedback Pin Input
Current IFB 100 nA
Continuous Output Current IOUT VIN = 5V, 0.603V <VOUT < 3.3V,
TA = -40°C to +85°C 600 mA
Continuous Output Current IOUT VIN = 5V, 0.603V <VOUT < 3.3V,
TA = -10°C to +85°C
(Application Circuit Figure 6) 700 mA
Shut-Down Current ISD Enable = Low 0.75 µA
PFET OCP Threshold IILM 2.4V ≤VIN ≤5.5V, 0.6V ≤ VIN ≤ 3.3V 1.4 2 A
VS0-VS2, Enable Voltage
Threshold VTH Pin = Low 0.0 0.4
Pin = High 1.4 VIN
VS0-VS2 Pin Input Current IVSX 1 nA
Operating Frequency FOSC 4 MHz
Soft Start Operation
Soft-Start Slew Rate VSS VID programming mode 0.975 1.5 2.025 V/mS
VOUT Rise Time TSS VFB programming mode 0.784 1.2 1.628 mS
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 5 www.enpirion.com
Typical Performance Characteristics
Efficiency Versus Load; VIN = 3.3V,
VOUT (from top to bottom) 2.5V, 1.8V, 1.5V, 1.2V.
Efficiency Versus Load; VIN = 3.7V,
VOUT (from top to bottom) 2.5V, 1.8V, 1.5V, 1.2V.
Efficiency Versus Load; VIN = 5V,
VOUT (from top to bottom) 3.3V, 2.5V, 1.8V, 1.5V, 1.2V.
Transient, VIN = 3.6V, VOUT = 1.2V, Load = 0-500mA
Startup, VIN = 3.6V, VOUT = 1.5V, Load = 500mA
Shutdown, VIN = 3.6V, VOUT = 1.5V, Load = 500mA
50
55
60
65
70
75
80
85
90
95
100
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70
Load Current (A)
Efficiency (%)
50
55
60
65
70
75
80
85
90
95
100
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70
Load Current (A)
Efficiency (%)
50
55
60
65
70
75
80
85
90
95
100
0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70
Load Current (A)
Efficiency (%)
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 6 www.enpirion.com
Voltage Ripple, VIN = 3.3V, VOUT = 1.8V, Load = 0mA
COUT = 1x 22µ
µµ
µF, 0805, 2.0mV/Div.
Voltage Ripple, VIN = 3.3V, VOUT = 1.8V, Load = 600mA
COUT = 1x 22µ
µµ
µF, 0805, 2.0mV/Div.
Voltage Ripple, VIN = 3.3V, VOUT = 1.8V, Load = 0mA
COUT = 2x 10µ
µµ
µF, 0805, 2.0mV/Div.
Voltage Ripple, VIN = 3.3V, VOUT = 1.8V, Load = 600mA
COUT = 2x 10µ
µµ
µF, 0805, 2.0mV/Div.
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 7 www.enpirion.com
Functional Block Diagram
Figure 4: Functional Block Diagram
Voltage
Select
DAC
Switch
VREF
(+)
(-)
Error
Amp
V
SENSE
V
FB
V
OUT
VS0 VS1 VS2
Package Boundry
P-Drive
N-Drive
UVLO
Thermal Limit
Current Limit
Soft Start
Sawtooth
Generator
(+)
(-)PWM
Comp
V
IN
ENABLE
GND
Logic
Compensation
Network
NC(SW)
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 8 www.enpirion.com
Detailed Description
Functional Overview
The EP5368QI is a complete DCDC converter
solution requiring only two low cost MLCC
capacitors. MOSFET switches, PWM
controller, Gate-drive, compensation, and
inductor are integrated into the tiny 3mm x
3mm x 1.1mm package to provide the smallest
footprint possible while maintaining high
efficiency, low ripple, and high performance.
The converter uses voltage mode control to
provide the simplest implementation and high
noise immunity. The device operates at a
4MHz switching frequency. The high switching
frequency allows for a wide control loop
bandwidth providing excellent transient
performance. The high switching frequency
further enables the use of very small
components making possible this
unprecedented level of integration.
Enpirion’s proprietary power MOSFET
technology provides very low switching loss at
frequencies of 4 MHz and higher, allowing for
the use of very small internal components, and
high performance. Integration of the magnetics
virtually eliminates the design/layout issues
normally associated with switch-mode DCDC
converters. All of this enables much easier
and faster incorporation into various
applications to meet demanding EMI
requirements.
Output voltage is chosen from seven preset
values via a three pin VID voltage select
scheme. An external divider option enables
the selection of any voltage in VIN to 0.603V
range. This reduces the number of
components that must be qualified and
reduces inventory burden. The VID pins can
be toggled on the fly to implement glitch free
dynamic voltage scaling.
Protection features include under-voltage lock-
out (UVLO), over-current protection (OCP),
short circuit protection, and thermal overload
protection.
Integrated Inductor
Enpirion has introduced the world’s first
product family featuring integrated inductors.
The EP5368QI utilizes a proprietary low loss
integrated inductor. The use of an internal
inductor localizes the noises associated with
the output loop currents. The inherent shielding
and compact construction of the integrated
inductor reduces the radiated noise that
couples into the traces of the circuit board.
Further, the package layout is optimized to
reduce the electrical path length for the AC
ripple currents that are a major source of
radiated emissions from DCDC converters.
The integrated inductor significantly reduces
parasitic effects that can harm loop stability,
and makes layout very simple.
Stable Over Wide Range of Operating
Conditions
The EP5368QI utilizes an internal type III
compensation network and is designed to
provide a high degree of stability over a wide
range of operating conditions. The device
operates over the entire input and output
voltage range with no external modifications
required. The very high switching frequency
allows for a very wide control loop bandwidth.
Soft Start
Internal soft start circuits limit in-rush current
when the device starts up from a power down
condition or when the “ENABLE” pin is
asserted “high”. Digital control circuitry limits
the VOUT ramp rate to levels that are safe for
the Power MOSFETS and the integrated
inductor.
The EP5368QI has two soft start operating
modes. When VOUT is programmed using a
preset voltage in VID mode, the device has a
constant slew rate. When the EP5368QI is
configured in external resistor divider mode,
the device has a constant VOUT ramp time.
Output voltage slew rate and ramp time is
given in the Electrical Characteristics Table.
Excess bulk capacitance on the output of the
device can cause an over-current condition at
startup.
03260 09/23/2010 Rev: F
EP5368QI
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When operating in VID mode, the maximum
total capacitance on the output, including the
output filter capacitor and bulk and decoupling
capacitance, at the load, is given as:
COUT_TOTAL_MAX = COUT_Filter + COUT_BULK = 700uF
When the EP5368QI output voltage is
programmed using and external resistor divider
the maximum total capacitance on the output is
given as:
COUT_TOTAL_MAX = 1.251x10-3/VOUT Farads
The above number and formula assume a no
load condition at startup.
Over Current/Short Circuit Protect ion
The current limit function is achieved by
sensing the current flowing through a sense P-
MOSFET which is compared to a reference
current. When this level is exceeded the P-
FET is turned off and the N-FET is turned on,
pulling VOUT low. This condition is maintained
for a period of 1mS and then a normal soft start
is initiated. If the over current condition still
persists, this cycle will repeat in a “hiccup”
mode.
Under Voltage Lockout
During initial power up an under voltage
lockout circuit will hold-off the switching
circuitry until the input voltage reaches a
sufficient level to insure proper operation. If
the voltage drops below the UVLO threshold,
the lockout circuitry will again disable the
switching. Hysteresis is included to prevent
chattering between states.
Enable
The ENABLE pin provides a means to shut
down the converter or enable normal
operation. A logic low will disable the converter
and cause it to shut down. A logic high will
enable the converter into normal operation. In
shutdown mode, the device quiescent current
will be less than 1 uA.
NOTE: This pin must not be left floating.
Thermal Shutdown
When excessive power is dissipated in the
chip, the junction temperature rises. Once the
junction temperature exceeds the thermal
shutdown temperature the thermal shutdown
circuit turns off the converter output voltage
thus allowing the device to cool. When the
junction temperature decreases by 15C, the
device will go through the normal startup
process.
Application Information
Output Voltage Select
To provide the highest degree of flexibility in
choosing output voltage, the EP5368QI uses a
3 pin VID, or Voltage ID, output voltage select
arrangement. This allows the designer to
choose one of seven preset voltages, or to use
an external voltage divider. Internally, the
output of the VID multiplexer sets the value for
the voltage reference DAC, which in turn is
connected to the non-inverting input of the
error amplifier. This allows the use of a single
feedback divider with constant loop gain and
optimum compensation, independent of the
output voltage selected.
Table 1 shows the various VS0-VS2 pin logic
states and the associated output voltage
levels. A logic “1” indicates a connection to
VIN or to a “high” logic voltage level. A logic
“0” indicates a connection to ground or to a
“low” logic voltage level. These pins can be
either hardwired to VIN or GND or alternatively
can be driven by standard logic levels. Logic
low is defined as VLOW ≤ 0.4V. Logic high is
defined as VHIGH ≥ 1.4V. Any level between
these two values is indeterminate. These pins
must not be left floating.
03260 09/23/2010 Rev: F
EP5368QI
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Table 1 VID Voltage Select Settings
VS2 VS1 VS0 VOUT
0 0 0 3.3V
0 0 1 2.5V
0 1 0 1.8V
0 1 1 1.5V
1 0 0 1.25V
1 0 1 1.2V
1 1 0 0.8V
1 1 1 User
Selectable
External Voltage Divider
As described above, the external voltage
divider option is chosen by connecting the
VS0, VS1, and VS2 pins to VIN or logic “high”.
The EP5368QI uses a separate feedback pin,
VFB, when using the external divider. VSENSE
must be connected to VOUT as indicated in
Figure 5.
Figure 5: External Divider Application Circuit
The output voltage is selected by the following
formula:
(
)
Rb
Ra
OUT VV += 1603.0
Ra must be chosen as 200kΩ to maintain loop
gain. Then Rb is given as:
Ω
−
=603.0
10206.1 5
OUT
bVx
R
VOUT can programmed over the range of 0.603V
to VIN-0.4V.
Dynamically Adjustable Output
The EP5368QI is designed to allow for
dynamic switching between the predefined VID
voltage levels The inter-voltage slew rate is
optimized to prevent excess undershoot or
overshoot as the output voltage levels
transition. The slew rate is identical to the soft-
start slew rate and is provided in the electrical
characteristics table.
Dynamic transitioning between internal VID
settings and the external divider is not allowed.
Input and Output Capacitors
The input capacitance requirement is 4.7uF
0603 MLCC. The input capacitor must be a
X5R/X7R MLCC. Y5V or equivalent dielectric
formulations lose capacitance with frequency,
bias, and with temperature, and are not
suitable for switch-mode DC-DC converter
input filter applications.
The output capacitance requirement is
approximately 20uF. Enpirion recommends a
single 22uF 0805 MLCC. Ripple performance
can be improved by using 2 x 10uF 0805 MLC
capacitors.
As described in the Soft Start section, there is
a limitation on the maximum bulk capacitance
that can be placed on the output of this device.
Please refer to that section for more details.
The output capacitor must be a X5R/X7R or
equivalent MLCC. Y5V or equivalent dielectric
formulations lose capacitance with frequency,
bias, and temperature and are not suitable for
switch-mode DC-DC converter output filter
applications.
Please consult Enpirion Applications Support
for other capacitor case size combinations.
Operation at 700mA Output Current
Operation at 700mA is supported by using the
application circuit shown in Figure 6. The
modification in the compensation is to ensure
stability over the entire set of input and output
voltage conditions.
VIN VSense
Vin
VS1
VS2
VS0
EP5368QI 22µF
0805
4.7uF
0603
VOUT
Vout
GND
ENABLE
Ra
Rb
VFB
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 11 www.enpirion.com
Figure 6: Applications Circuit for Operation at
700mA
For 700mA operation, use the following
component values:
1) Ra = 249kΩ
2) Ca = 15pF 0402 MLCC capacitor.
3) Then Rb is given as:
Ω
−
=603.0
10501.1 5
OUT
bVx
R
VOUT can be programmed over the range of
0.603V to VIN-0.4V.
4) Do not connect the sense line.
NOTE: Stability cannot be assured if these
guidelines are not followed.
Recommended PCB Footprint
Figure 7: EP5368QI Package PCB Footprint
VIN VSense
Vin
V
S1
V
S2
V
S0
EP5368QI 22µF
0805
4.7uF
0603
VOUT
Vout
GND
ENABLE
Ra
Rb
VFB
Ca
03260 09/23/2010 Rev: F
EP5368QI
Enpirion 2010 all rights reserved, E&OE 12 www.enpirion.com
Package Dimensions
Figure 8: EP5368QI Package Dimensions
NOTE: for details on product marking, please refer to the product marking guide which can be found
on the Enpirion Website WWW.ENPIRION.COM
Contact Information
Enpirion, Inc.
Perryville III
53 Frontage Road Suite 210
Hampton, NJ 08827
Phone: +1 908-894-6000
Fax: +1 908-894-6090
Enpirion reserves the right to make changes in circuit design and/or specifications at any time without notice. Information furnished by Enpirion is
believed to be accurate and reliable. Enpirion assumes no responsibility for its use or for infringement of patents or other third party rights, which may
result from its use. Enpirion products are not authorized for use in nuclear control systems, as critical components in life support systems or equipment
used in hazardous environment without the express written authority from Enpirion.