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MAX1795/MAX1796/
MAX1797
Low-Supply Current, Step-Up DC-DC Converters
with True Shutdown
General Description
The MAX1795/MAX1796/MAX1797 are high-efficiency,
step-up DC-DC converters intended for small portable
hand-held devices. These devices feature Maxim’s True
Shutdown™ circuitry, which fully disconnects the out-
put from the input in shutdown, improves efficiency,
and eliminates costly external components. All three
devices also feature Maxim’s proprietary LX-damping
circuitry for reduced EMI in noise-sensitive applications.
For additional in-system flexibility, a battery monitoring
comparator (LBI/LBO) remains active even when the
DC-DC converter is in shutdown.
The input voltage range is +0.7V to VOUT, where VOUT
can be set from +2V to +5.5V. Startup is guaranteed
from +0.85V. The MAX1795/MAX1796/MAX1797 have a
preset, pin-selectable 5V or 3.3V output. The output can
also be adjusted to other voltages, using two external
resistors. The three devices differ only in their current
limits, allowing optimization of external components for
different loads: The MAX1795, MAX1796, and MAX1797
have current limits of 0.25A, 0.5A, and 1A, respectively.
All devices are packaged in a compact, 8-pin μMAX
package that is only 1.09mm tall and half the size of an
8-pin SO.
Applications
● Portable Digital Audio Players
● PDAs/Palmtops
● Wireless Handsets
● Portable Terminals
Pin Configuration
TOP VIEW
LBI 1
FB 2
LBO 3
SHDN 4
MAX1795
MAX1796
MAX1797
µMAX
8 BATT
7 OUT
6 LX
5 GND
Features
● > 95% Efficiency
● True-Shutdown Circuitry
• Output Disconnects from Input in Shutdown
• No External Schottky Diode Needed
25μA Quiescent Supply Current
● Low-Noise Antiringing Feature
● LBI/LBO Comparator Enabled in Shutdown
2μA Shutdown Current
8-Pin μMAX Package
Ordering Information
PART
MAX1795EUA
MAX1796EUA
MAX1797EUA
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 μMAX
8 μMAX
8 μMAX
Typical Operating Circuit
IN
0.7V TO
5.5V
BATT
LX
OFF
ON
LBI
MAX1795
MAX1796
OUT
MAX1797 FB
LBO
SHDN
GND
OUT
True Shutdown is a trademark of Maxim Integrated Products.
19-1798; Rev 0; 12/00

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MAX1795/MAX1796/
MAX1797
Low-Supply Current, Step-Up DC-DC Converters
with True Shutdown
Absolute Maximum Ratings
OUT, LX, SHDN, LBI, LBO, BATT to GND...............-0.3V to +6V
FB............................................................ -0.3V to (VOUT + 0.3V)
ILX, IOUT..............................................................................±1.5A
Output Short-Circuit Duration................................................... 5s
Continuous Power Dissipation
8-Pin μMAX (derate 4.1mW/°C above +70°C).............330mW
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
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.
Electrical Characteristics
(VBATT = +2V, OUT = FB (VOUT = +3.3V), SHDN = LBI = GND, TA = 0°C to +85°C, unless otherwise noted. Typical values are at
TA = +25°C.)
PARAMETER
Minimum Input Voltage
Operating Voltage
Startup Voltage
Startup Voltage Tempco
Output Voltage
Adjustable Output Voltage Range
Steady-State Output Current
Feedback Set-Point Voltage
(Adjustable Mode)
Feedback Input Current
Internal NFET, PFET
On-Resistance
LX Switch Current Limit
(NFET only)
LX Leakage Current
Synchronous Rectifier Turn-Off
Current Limit
Damping Switch On-Resistance
Operating Current into OUT
(Note 2)
SYMBOL
VBATT
CONDITIONS
After startup
(Note 1)
TA = +25°C, RL = 3kΩ
VOUT
FB = OUT
FB = GND
IOUT
VFB
IFB
RDS(ON)
ILIM
ILEAK
BATT = +2V,
FB = OUT
(VOUT = +3.3V)
BATT = +2V,
FB = GND
(VOUT = +5.0V)
MAX1795
MAX1796
MAX1797
MAX1795
MAX1796
MAX1797
VOUT = +2V to +5.5V
VFB = +1.24V
VOUT = +3.3V,
ILX = 100mA
NFET
PFET
MAX1795
MAX1796
MAX1797
VLX = 0 and +5.5V, VOUT = +5.5V
RDAMP
VFB = +1.4V
MIN
1.0
3.17
4.80
2.0
100
200
400
50
100
250
1.20
0.2
0.4
0.8
100
TYP
0.7
0.85
-2.2
3.3
5.0
180
300
550
120
200
370
MAX
5.5
1.0
3.43
5.20
5.5
UNITS
V
V
V
mV/°C
V
V
mA
1.24 1.28
V
4
0.17
0.27
0.25
0.5
1.0
0.2
100
0.3
0.45
0.35
0.625
1.25
nA
A
µA
25 mA
200 400
25 45
µA
www.maximintegrated.com
Maxim Integrated 2

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MAX1795/MAX1796/
MAX1797
Low-Supply Current, Step-Up DC-DC Converters
with True Shutdown
Electrical Characteristics (continued)
(VBATT = +2V, OUT = FB (VOUT = +3.3V), SHDN = LBI = GND, TA = 0°C to +85°C, unless otherwise noted. Typical values are at
TA = +25°C.)
PARAMETER
Operating Current into BATT
Shutdown Current into BATT
LX Switch MaxImum On-Time
LX Switch Minimum Off-Time
LBI Threshold Voltage Falling
LBI Hysteresis
LBI Input Current
LBO Low Output Voltage
LBO Off-Leakage Current
SHDN Input Voltage
Shutdown Input Current
SYMBOL
tON
tOFF
VLBI
CONDITIONS
VFB = +1.4V, VLBI = +1V
SHDN = BATT, VLBI = +1V
VFB = +1V, if current limit not reached
VFB = +1V
VBATT = +2V
VBATT = LBI
ILBI VLBI = +0.8V
VBATT = VLBI = +0.975V,
sinking 20µA (50Ω typ)
VBATT = VLBI = +1.1V,
sinking 100µA (25Ω typ)
VLBO = +5.5V
VIL
VIH
VSHDN = 0 and +5.5V
MIN
3
0.8
0.8
0.875
TYP
2
2
4
1
0.85
0.925
25
9
MAX
4
4
5
1.2
0.90
0.975
100
UNITS
µA
µA
µs
µs
V
mV
nA
0.1
V
0.1
1 100 nA
0.8 x
VBATT
0.2 x
VBATT
V
100 nA
Electrical Characteristics
(VBATT = +2V, OUT = FB (VOUT = +3.3V), SHDN = LBI = GND, TA = -40°C to +85°C, unless otherwise noted.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN MAX
Operating Voltage
Output Voltage
VBATT
VOUT
Note 1
FB = OUT
FB = GND
1.0
3.13
4.75
5.5
3.47
5.25
Adjustable Output Voltage Range
2.0 5.5
Steady-State Output Current
(Note 1)
IOUT
FB = OUT
(VOUT = +3.3V)
FB = GND
(VOUT = +5.0V)
MAX1795
MAX1796
MAX1797
MAX1795
MAX1796
MAX1797
100
200
400
60
125
250
Feedback Set-Point Voltage
(Adjustable Mode)
VFB VOUT = +2V to +5.5V
1.19
1.29
Feedback Input Current
IFB VFB = +1.25V
100
UNITS
V
V
V
mA
V
nA
www.maximintegrated.com
Maxim Integrated 3

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MAX1795/MAX1796/
MAX1797
Low-Supply Current, Step-Up DC-DC Converters
with True Shutdown
Electrical Characteristics (continued)
(VBATT = +2V, OUT = FB (VOUT = +3.3V), SHDN = LBI = GND, TA = -40°C to +85°C, unless otherwise noted.) (Note 3)
PARAMETER
Internal NFET, PFET
On-Resistance
LX Switch Current Limit
(NFET only)
SYMBOL
RDS(ON)
ILIM
CONDITIONS
VOUT = +3.3V,
ILX = 100mA
NFET
PFET
MAX1795
MAX1796
MAX1797
MIN
0.19
0.35
0.8
MAX
0.3
0.45
0.37
0.7
1.32
UNITS
A
LX Leakage Current
Damping Switch On-Resistance
Operating Current into OUT
(Note 2)
Operating Current into BATT
Shutdown Current into BATT
LX Switch Maximum On-Time
LX Switch Minimum Off-Time
LBI Threshold Voltage
LBI Input Current
LBO Low Output Voltage
ILEAK
RDAMP
tON
tOFF
VLBI
ILBI
VLX = 0 and +5.5V, VOUT = +5.5V
VFB = +1.4V
VFB = +1.4V, VLBI = +1V
SHDN = BATT, VLBI = +1V
VFB = +1V, if current limit not reached
VFB = +1V
VBATT = +2V
VBATT = LBI
VLBI = +0.8V
VBATT = VLBI = +0.975V,
sinking 20µA (50Ω typ)
VBATT = VLBI = +1.1V,
sinking 100µA (25Ω typ)
100
2.75
0.7
0.8
0.875
400
45
4
4
5.25
1.3
0.90
0.975
100
0.1
0.1
µA
µA
µA
µA
µs
µs
V
nA
V
LBO Off-Leakage Current
SHDN Input Voltage
Shutdown Input Current
VLBO = +5.5V
VIL
VIH
VSHDN = 0 and +5.5V
0.8 x
VBATT
100
0.2 x
VBATT
nA
V
100 nA
Note 1: Operating Voltage: Since the regulator is bootstrapped to the output, once started it will operate down to a 0.7V input.
Note 2: Device is bootstrapped (power to IC comes from OUT). This correlates directly with the actual battery supply current.
Note 3: Specifications to -40°C are guaranteed by design, not production tested.
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Maxim Integrated 4

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MAX1795/MAX1796/
MAX1797
Low-Supply Current, Step-Up DC-DC Converters
with True Shutdown
Typical Operating Characteristics
(L = 22μH, CIN = 47μF, COUT = 47μF, TA = +25°C, unless otherwise noted.)
MAX1795
EFFICIENCY vs. LOAD CURRENT (+5V)
100 VBATT = +3.6V
90
80
70 VBATT = +2.4V VBATT = +1.2V
60
50
40
30
20
10
0
0.1
1 10 100
LOAD CURRENT (mA)
1000
MAX1796
EFFICIENCY vs. LOAD CURRENT (+3.3V)
100 VBATT = +2.4V
90
80
70 VBATT = +1.2V
60
50
40
30
20
10
0
0.1
1 10 100
LOAD CURRENT (mA)
1000
NO-LOAD BATTERY CURRENT
vs. INPUT BATT VOLTAGE
300
250
200
150
100 VOUT = +5V
50
VOUT = +3.3V
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
BATT VOLTAGE (V)
MAX1795
EFFICIENCY vs. LOAD CURRENT (+3.3V)
100 VBATT = +2.4V
90
80
70 VBATT = +1.2V
60
50
40
30
20
10
0
0.1
L = 10µH
1 10 100
LOAD CURRENT (mA)
1000
MAX1797
EFFICIENCY vs. LOAD CURRENT (+5V)
100
90 VBATT = +3.6V
80
70
60 VBATT = +2.4V
50 VBATT = +1.2V
40
30
20
10
0
0.1
1 10 100
LOAD CURRENT (mA)
1000
STARTUP VOLTAGE
vs. LOAD CURRENT
4.0
3.5
3.0
2.5
VOUT = +3.3V
2.0
1.5
1.0
0.5
0
0.1 1 10 100 1000
LOAD CURRENT (mA)
MAX1796
EFFICIENCY vs. LOAD CURRENT (+5V)
100 VBATT = +3.6V
90
80
70
VBATT = +2.4V
VBATT = +1.2V
60
50
40
30
20
10
0
0.1
1 10 100
LOAD CURRENT (mA)
1000
MAX1797
EFFICIENCY vs. LOAD CURRENT (+3.3V)
100
VBATT = +2.4V
90
80
70
60
50 VBATT = +1.2V
40
30
20
10
0
0.1
1 10 100
LOAD CURRENT (mA)
1000
SHUTDOWN THRESHOLD
vs. INPUT BATT VOLTAGE
3.0
2.5
2.0
1.5
1.0
0.5
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
BATT VOLTAGE (V)
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Maxim Integrated 5