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1
2
3
4
8
7
6
5
OUT
CXP
CXN
PGNDGND
IN
SHDN
AOUT
MAX1595
µMAX
TOP VIEW
OUTPUT
OUT
IN
INPUT
SHDN
GND
CXN CXP
PGND
AOUT
MAX1595
MAX1595
Regulated 3.3V/5.0V Step-Up/Step-Down
Charge Pump
Maxim Integrated Products
Typical Operating Circuit
19-2107; Rev 3; 10/11
General Description
The MAX1595 charge-pump regulator generates either
3.3V or 5V from a 1.8V to 5.5V input. The unique control
architecture allows the regulator to step up or step down
the input voltage to maintain output regulation. The
1MHz switching frequency, combined with a unique
control scheme, allows the use of a ceramic capacitor
as small as 1µF for 125mA of output current. The com-
plete regulator requires three external capacitors—no
inductor is needed. The MAX1595 is specifically
designed to serve as a high-power, high- efficiency aux-
iliary supply in applications that demand a compact
design. The MAX1595 is offered in space-saving 8-pin
µMAX®and high-power 12-pin TQFN packages.
Applications
White LED Power
Flash Memory Supplies
Battery-Powered Applications
Miniature Equipment
PCMCIA Cards
3.3V to 5V Local Conversion Applications
Backup-Battery Boost Converters
3V to 5V GSM SIMM Cards
Features
oUltra-Small: Requires Only Three Ceramic
Capacitors
oNo Inductors Required
oUp to 125mA Output Current
oRegulated ±3% Output Voltage
o1MHz Switching Frequency
o1.8V to 5.5V Input Voltage
o220µA Quiescent Current
o0.1µA Shutdown Current
oLoad Disconnect in Shutdown
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX1595EUA33+ -40°C to +85°C 8 µMAX
MAX1595ETC33+ -40°C to +85°C 12 TQFN-EP*
MAX1595EUA50+ -40°C to +85°C 8 µMAX
MAX1595ETC50+ -40°C to +85°C 12 TQFN-EP*
Pin Configurations continued at end of data sheet.
Selector Guide
PART VOUT (V)** TOP M ARK
MAX1595EUA33+ 3.3 —
MAX1595ETC33+ 3.3 AAEH
MAX1595EUA50+ 5.0 —
MAX1595ETC50+ 5.0 AAEI
**
Contact factory for other fixed-output voltages from 2.7V to 5.0V.
Pin Configurations
+
Denotes a lead(Pb)-free/RoHS-compliant package.
*
EP = Exposed pad.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
MAX1595
Regulated 3.3V/5.0V Step-Up/
Step-Down Charge Pump
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = 2V for MAX1595_ _ _33, VIN = 3V for MAX1595_ _ _50, CIN = 1µF, CX= 0.22µF, COUT = 1µF, TA= -40° to +85°C, unless otherwise
noted. Typical values are at TA= +25°C.) (Note 2)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN, OUT, AOUT to GND............................................-0.3V to +6V
SHDN to PGND ........................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
CXN to PGND.....................-0.3V to (Lower of IN + 0.8V or 6.3V)
CXP to GND ................................-0.8V to (Higher of OUT + 0.8V
or IN + 0.8V but not greater than 6V)
Continuous Output Current ...............................................150mA
Continuous Power Dissipation (TA= +70°C)
µMAX (derate 4.8mW/°C above +70°C) ..................387.8mW
TQFN-EP (derate 24.4mW/°C above +70°C).........1951.2mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage Range VIN 1.8 5.5 V
Input Undervoltage Lockout
Threshold 1.40 1.60 1.72 V
Input Undervoltage Lockout
Hysteresis 40 mV
TA = 0°C to +85°C 4.85 5.05 5.15
0 < IL OA D
< 125m A,
V
I N
= + 3.0V TA = -40°C to +85°C 4.80 5.20
TA = 0°C to +85°C 3.20 3.33 3.40
0 < ILOAD < 75mA, VIN
= +2.0V TA = -40°C to +85°C 3.16 3.44
TA = 0°C to +85°C 3.20 3.33 3.40
Output Voltage VOUT
0 < ILOAD < 30mA, VIN
= +1.8V TA = -40°C to +85°C 3.16 3.44
V
VIN = +2.0V, MAX1595_ _ _33 220 320
No-Load Input Current IQVIN = +3.0V, MAX1595_ _ _50 240 350 µA
Switching Frequency fOSC IL OA D
> 20m A, V
OU T
> VIN 0.85 1.0 1.15 MHz
Shutdown Supply Current ISHDN VSHDN = 0V, VIN = +5.5V, VOUT = 0V 5 µA
SHDN Input Voltage Low V
IN LVIN = 2.0V to 5.5V 0.6 V
SHDN Input Voltage High V
IN HVIN = 2.0V to 5.5V 1.6 V
SHDN Input Leakage Current 0.1 µA
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
TQFN
Junction-to-Ambient Thermal Resistance (θJA)..........41°C/W
Junction-to-Case Thermal Resistance (θJC).................6°C/W
µMAX
Junction-to-Ambient Thermal Resistance (θJA).....206.3°C/W
Junction-to-Case Thermal Resistance (θJC)...............42°C/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
MAX1595
Regulated 3.3V/5.0V Step-Up/Step-Down
Charge Pump
_______________________________________________________________________________________
3
__________________________________________Typical Operating Characteristics
(Circuit of Figure 4, VIN = 2V for MAX1595_ _ _33, VIN = 3V for MAX1595_ _ _50, TA = +25°C, unless otherwise noted.)
0.1
10
1
1000
100
10000
021345
NO LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX1595 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
6
VOUT = 5V
200ns/div
OUTPUT WAVEFORM
50mV/div
MAX1595 toc02
OUTPUT WAVEFORM. AC-COUPLED.
VIN = 3.6V, ILOAD = 100mA, COUT = 1µF
VOUT = 5V
4.90
5.00
4.98
4.96
4.94
4.92
5.06
110100
1000
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1595 toc03
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
5.04
5.02
VIN = 3V
VIN = 3.6V
VIN = 3.3V
VOUT = 5V
100
0
1 10 100
3V EFFICIENCY
vs. LOAD CURRENT
20
10
MAX1595 toc04
LOAD CURRENT (mA)
EFFICIENCY (%)
40
30
60
70
50
80
90
VIN = 1.8V
VIN = 2.4V
2ms/div
LINE-TRANSIENT RESPONSE
MAX1595 toc07
A: INPUT VOLTAGE: VIN = 3.1V TO 3.6V, 500mV/div
B: OUTPUT VOLTAGE: ILOAD = 50mA, 100mV/div
A
B
100
0
0.1 1 10 100 1000
5V EFFICIENCY
vs. LOAD CURRENT
20
MAX1595 toc05
LOAD CURRENT (mA)
EFFICEINCY (%)
40
60
80
70
50
30
10
90
VIN = 3.6V
VIN = 3.3V
VIN = 3V
100µs/div
SHUTDOWN TIMING
MAX1595 toc06
A: OUTPUT VOLTAGE: RL = 100Ω, 2V/div
B: SHDN VOLTAGE: 2V/div
A5V
B
200µs/div
LOAD-TRANSIENT RESPONSE
MAX1595 toc08
A: LOAD CURRENT: ILOAD = 5mA to 95mA, 100mA/div
B: OUTPUT VOLTAGE: AC-COUPLED 100mV/div
A
B
COUT = 1µF
1
0
2
4
3
5
6
02
13456
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX1595 toc09
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE (V)
VOUT = 5V, ILOAD = 125mA
VOUT = 3.3V, ILOAD = 75mA
Detailed Description
The MAX1595 charge pump provides either a 3.3V or 5V
regulated output. It delivers a maximum 125mA load cur-
rent. In addition to boost regulating from a lower supply,
it is also capable of buck regulating from supplies that
exceed the regulated output by a diode drop or more.
Designed specifically for compact applications, a com-
plete regulator circuit requires only three small external
capacitors. An innovative control scheme provides con-
stant frequency operation from medium to heavy loads,
while smoothly transitioning to low-power mode at light
loads to maintain optimum efficiency. In buck mode,
switch S1 (Figure 1) is switched continuously to IN, while
switch S2 alternates between IN and OUT. An amount of
charge proportional to the difference between the output
voltage and the supply voltage is stored on CX, which
gets transferred to the output when the regulation point is
reached. Maximum output ripple is proportional to the
difference between the supply voltage and the output
voltage, as well as to the ratio of the transfer capacitor
(CX) to the output capacitor (COUT).
The MAX1595 consists of an error amplifier, a 1.23V
bandgap reference, internal resistive feedback network,
oscillator, high-current MOSFET switches, and shutdown
and control logic. Figure 1 shows an idealized unregulat-
ed charge-pump voltage doubler. The oscillator runs at a
50% duty cycle. During one half of the period, the trans-
fer capacitor (CX) charges to the input voltage. During
the other half, the doubler transfers the sum of CXand
input voltage to the output filter capacitor (COUT). Rather
than doubling the input voltage, the MAX1595 provides a
regulated output voltage of either 3.3V or 5.0V.
Shutdown
Driving SHDN low places the device in shutdown mode.
The device draws 0.1μA of supply current in this mode.
When driven high, the MAX1595 enters a soft-start
mode. Soft-start mode terminates when the output volt-
age regulates, or after 2ms, whichever comes first. In
shutdown, the output disconnects from the input.
Undervoltage Lockout
The MAX1595 has an undervoltage-lockout that deacti-
vates the devices when the input voltage falls below 1.6V.
Below UVLO, hysteresis holds the device in shutdown until
the input voltage rises 40mV above the lockout threshold.
IN
S1
S2
CIN COUT
OUT
CX
OSC
Figure 1. Unregulated Voltage Doubler
MAX1595
Regulated 3.3V/5.0V Step-Up/
Step-Down Charge Pump
4 _______________________________________________________________________________________
Pin Description
PIN
µMAX TQFN-EP NAME FUNCTION
112AOUT
Analog Power and Sense Input for Error Amplifier/Comparator. Connect to OUT at
output filter capacitor.
21SHDN Shutdown Input. When SHDN = low, the device turns off; when SHDN = high, the device
activates. In shutdown, OUT is disconnected from IN.
3 2, 3 IN Input Supply. Can range from 1.8V to 5.5V. Bypass to GND with a 1μF capacitor.
4 4 GND Ground
5 5, 6 PGND Power Ground
6 7, 8 CXN Negative Terminal of the Charge-Pump Transfer Capacitor
7 9 CXP Positive Terminal of the Charge-Pump Transfer Capacitor
8 10, 11 OUT Output. Bypass to GND with output capacitor filter.
——EP
Exposed Pad. Internally connected to GND. Connect to a large ground plane to
maximize thermal performance. Not intended as an electrical connection point (TQFN
package only).
MAX1595
Regulated 3.3V/5.0V Step-Up/Step-Down
Charge Pump
_______________________________________________________________________________________ 5
Applications Information
Using white LEDs to backlight LCDs is an increasingly
popular approach for portable information devices
(Figure 2). Because the forward voltage of white LEDs
exceeds the available battery voltage, the use of a
charge pump such as the MAX1595 provides high effi-
ciency, small size, and constant light output with chang-
ing battery voltages. If the output is used only to light
LEDs, the output capacitor can be greatly reduced. The
frequency modulation of the LED intensity is not dis-
cernible to the human eye, and the smaller capacitor
saves both size and cost.
Adding two Schottky diodes and two capacitors imple-
ments a tripler and allows the MAX1595_ _ _50 to regu-
late a current of 75mA with a supply voltage as low as
2.3V (Figure 3).
Capacitor Selection
The MAX1595 requires only three external capacitors
(Figure 4). Their values are closely linked to the output
current capacity, oscillator frequency, output noise con-
tent, and mode of operation.
Generally, the transfer capacitor (CX) will be the smallest,
and the input capacitor (CIN) is twice as large as CX.
Higher switching frequencies allow the use of the smaller
CXand CIN. The output capacitor (COUT) can be any-
where from 5-times to 50-times larger than CX. Table 1
shows recommended capacitor values.
In addition, the following equation approximates output
ripple:
VRIPPLE ≅IOUT / (2 x fOSC x COUT)
Table 2 lists the manufacturers of recommended capaci-
tors. Ceramic capacitors will provide the lowest ripple
due to their typically lower ESR.
Power Dissipation
The power dissipated in the MAX1595 depends on out-
put current and is accurately described by:
PDISS = IOUT (2VIN - VOUT)
PDISS must be less than that allowed by the package
rating.
Layout Considerations
All capacitors should be soldered in close proximity to
the IC. Connect ground and power ground through a
short, low-impedance trace. The input supply trace
should be as short as possible. Otherwise, an additional
input supply filter capacitor (tantalum or electrolytic) may
be required.
AOUT
IN
INPUT
2.3V
1µF
SHDN
GNDPGND
OUT
MAX1595_ _ _50
0.22µF
CXP
CXN
1µF
OUTPUT
REGULATED 5V
75mA
1µF 0.22µF
OUT
IN
VIN
COUT =
0.47µF
CIN = 1µF
CX = 0.1µF
SHDN
GND
CXP CXN
PGND
AOUT
MAX1595_ _ _50
100Ω100Ω100Ω
Figure 3. Regulated Voltage Tripler
Figure 2. White LED Bias Supply
CX
0.22µF
CIN
1µFCOUT
1µF
OUT
CXN
CXP
SHDN
IN OUT
7
4
6
3
2
8
ON
OFF
GND
5
PGND AOUT 1
MAX1595
IN
Figure 4. Standard Operating Circuit
MAX1595
Regulated 3.3V/5.0V Step-Up/
Step-Down Charge Pump
6 _______________________________________________________________________________________
Chip Information
PROCESS: CMOS
Table 2. Recommended Capacitor Manufacturers
VALUE (µF) VOLTAGE (V) TYPE SIZE MANUFACTURER PART
110
X7R 0805 Taiyo Yuden LMK212BJ105MG
0.22 10 X7R 0603 Taiyo Yuden LMK107BJ224MA
0.47 10 X7R 0603 Taiyo Yuden LMK107BJ474MA
0.1 10 X7R 0603 Taiyo Yuden LMK107BJ104MA
Table 1. Recommended Capacitor Values
OUTPUT RIPPLE (mV) CIN (µF) CX (µF) COUT (µF)
70 1 0.22 1
35 2.2 0.47 2.2
12
AOUT
11
OUT
10
OUT
9 CXP
8 CXN
7 CXN
4
GND
5
PGND
6
PGND
1
SHDN
2IN
3IN
TQFN
TOP VIEW
MAX1595
Pin Configurations (continued)
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 μMAX U8+1 21-0036 90-0092
12 TQFN 1244+4 21-0139 90-0068
Regulated 3.3V/5.0V Step-Up/Down Charge
Pump
MAX1595
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in
the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________
7
© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
2 6/09 Added EP (exposed pad) and top mark information 1, 2, 4, 6
3 10/11 Updated Absolute Maximum Ratings section and added Package Thermal
Characteristics section 2
