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19-1802; Rev 2; 4/05
KIT
ATION
EVALU
BLE
AVAILA
High-Efficiency Step-Up Converters with
Reverse Battery Protection
General Description
The MAX1832–MAX1835 are high-efficiency step-up
converters with complete reverse battery protection that
protects the device and the load when the battery is
reversed. They feature a built-in synchronous rectifier,
which allows for over 90% efficiency and reduces size
and cost by eliminating the need for an external
Schottky diode.
These step-up converters operate from a +1.5V to +5.5V
input voltage range and deliver up to 150mA of load cur-
rent. The MAX1833EUT/MAX1835EUT (SOT devices)
have a fixed 3.3V output voltage. The MAX1833ETT30
(TDFN device) has a fixed 3.0V output voltage. The
MAX1832/MAX1834 have adjustable outputs from +2V to
+5.5V. In shutdown, the MAX1832/MAX1833 connect the
battery input to the voltage output, allowing the input bat-
tery to be used as a backup or real-time clock supply
when the converter is off (see Selector Guide).
MAX183_EUT devices are available in a miniature 6-pin
SOT23 package. The MAX1833ETT30 is available in a
3mm
✕
3mm thin DFN package. The MAX1832EVKIT is
available to speed designs.
Features
♦
Reverse Battery Protection for DC-DC Converter
and Load
♦
Up to 90% Efficiency
♦
No External Diode or FETs Needed
♦
Internal Synchronous Rectifier
♦
4µA Quiescent Current
♦
<1µA Shutdown Supply Current
♦
+1.5V to +5.5V Input Voltage Range
♦
Accurate
SHDN
Threshold for Low-Battery Cutoff
♦
BATT Connected to OUT in Shutdown for Backup
Power (MAX1832/MAX1833)
♦
RST
Output (MAX1833/MAX1835)
♦
Fixed 3.3V/3.0V Output Voltage
♦
Adjustable Output Voltage (MAX1832/MAX1834)
♦
Up to 150mA Output Current
♦
Tiny 6-Pin SOT23 Package
♦
Tiny 6-Pin Thin QFN Package (MAX1833ETT30)
MAX1832–MAX1835
________________________Applications
Medical Diagnostic Equipment
Pagers
Hand-Held Instruments
Remote Wireless Transmitters
Digital Cameras
Cordless Phones
Battery Backup
PC Cards
Local 3.3V or 5V Supply
Ordering Information
PART
MAX1832EUT-T
MAX1833EUT-T
MAX1833E
TT30-T
MAX1834EUT-T
MAX1835EUT-T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
6 SOT23-6
6 SOT23-6
6 TDFN-6
(T633-1)
6 SOT23-6
6 SOT23-6
TOP
MARK
AAOT
AAOU
ABX
AAOV
AAOW
Pin Configurations
OUT
RST
TOP VIEW
Selector Guide
LX
6
5
4
PART
MAX1832EUT-T
SHDN
1
6
FB (RST)
OUTPUT
VOLTAGE
Adjustable
Fixed 3.3V
Fixed 3.0V
Adjustable
Fixed 3.3V
OUTPUT VOLTAGE
IN SHUTDOWN
V
BATT
V
BATT
V
BATT
V
BATT
- 0.7V
V
BATT
- 0.7V
BATT
2
MAX1832
5
MAX1834
(MAX1833EUT)
(MAX1835)
4
OUT
MAX1833EUT-T
MAX1833ETT
MAX1833ETT30-T
MAX1834EUT-T
MAX1835EUT-T
GND
3
LX
1
SHDN
2
BATT
3
GND
SOT23
TDFN
3mm
✕
3mm
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
High-Efficiency Step-Up Converters with
Reverse Battery Protection
MAX1832–MAX1835
ABSOLUTE MAXIMUM RATINGS
BATT, LX to GND.........................................................-6V to +6V
LX to OUT ....................................................................-6V to +1V
SHDN
to GND..............................................-6V to (V
OUT
+ 0.3V)
OUT, FB,
RST
TO GND ............................................-0.3V to +6V
LX Current ................................................................................1A
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SOT23 (derate 9.1mW/°C above +70°C) ...........727mW
6-Pin 3mm
✕
3mm TDFN (derate 18.2mW/°C
above +70°C) .........................................................1454.5mW
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
(V
SHDN
= +1.5V, V
OUT
= +3.3V, V
BATT
= +2V, GND = 0, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
Output Range
Battery Input Range
Startup Battery Input Voltage
SYMBOL
V
OUT
V
BATT
V
SU
R
LOAD
= 2.6kΩ
MAX1833EUT/
MAX1835EUT
Output Voltage
V
OUT
MAX1833ETT30
FB Trip Voltage
V
FB
MAX1832/
MAX1834
MAX1832/
MAX1834,
V
FB
= +1.3V
V
OUT
= +3.3V
I
LX
= 100mA
V
OUT
= +3.3V
I
LX
= 100mA
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
0.73
435
400
3.5
V
OUT
= +3.3V
V
OUT
= +3.5V,
V
FB
= +1.3V
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
0.05
2
0
2.5
5
17
525
615
650
6.5
34
39
7.0
8.0
1
0.5
3.225
3.208
2.94
2.925
1.208
1.204
3.5
4.0
0.4
1.2
1.5
1.3
1.6
1.228
3.0
CONDITIONS
MAX1832/MAX1834
MIN
2.0
1.5
1.22
1.24
3.290
3.355
3.372
3.06
3.075
1.248
1.252
20
nA
Ω
Ω
V
mA
µs
mA
µA
µA
V
V
TYP
MAX
5.5
5.5
1.5
UNITS
V
V
V
FB Input Bias Current
I
FB
N-Channel On-Resistance
P-Channel On-Resistance
P-Channel Catch-Diode Voltage
N-Channel Switch Current Limit
Switch Maximum On-Time
Synchronous Rectifier Zero-
Crossing Current
Quiescent Current into OUT
(Note 2)
Shutdown Current into OUT
R
NCH
R
PCH
I
LX
= 100mA, PCH off, V
OUT
= +3.5V,
V
FB
= +1.3V
I
MAX
t
ON
V
OUT
= +3.3V
T
A
= +25°C
T
A
= -40°C to +85°C
V
OUT
= +3.5V, V
SHDN
= V
FB
= 0V
2
_______________________________________________________________________________________
High-Efficiency Step-Up Converters with
Reverse Battery Protection
ELECTRICAL CHARACTERISTICS (continued)
(V
SHDN
= +1.5V, V
OUT
= +3.3V, V
BATT
= +2V, GND = 0, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
Reverse Battery Current into
OUT
Quiescent Current into BATT
Shutdown Current into BATT
Reverse Battery Current into
BATT
SHDN
Logic Low
SHDN
Threshold
SHDN
Threshold Hysteresis
SHDN
Input Bias Current
SHDN
Reverse Battery Current
V
OUT
= +5.5V, V
SHDN
= +5.5V, T
A
= +25°C
V
OUT
= 0, V
BATT
= V
SHDN
= V
LX
= -3V
MAX1833EUT/
MAX1835EUT,
falling edge
MAX1833ETT30
RST
Voltage Low
RST
Leakage Current
LX Leakage Current
LX Reverse Battery Current
Maximum Load Current
Efficiency
I
LOAD
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
2.830
2.800
2.580
2.553
0.1
1
1
100
0.001
150
90
10
100
2.717
SYMBOL
CONDITIONS
V
OUT
= 0, V
BATT
= V
SHDN
= V
LX
= -3V
V
OUT
= +3.5V,
V
FB
= +1.3V
T
A
= +25°C
T
A
= -40°C to +85°C
0.001
0.002
MIN
TYP
0
1.8
MAX
10
5.0
6.0
1
10
0.3
1.185
1.170
0.02
13
52
2.980
100
150
3.110
3.140
2.836
2.863
0.2
100
V
nA
nA
µA
mA
%
V
1.228
1.271
1.286
UNITS
µA
µA
µA
µA
V
V
V
nA
µA
MAX1832–MAX1835
V
OUT
= +3.5V, V
BATT
= +2V, V
SHDN
= 0
V
OUT
= 0, V
BATT
= V
SHDN
= V
LX
= -3V
V
BATT
= +1.5V to +5.5V
Rising edge
T
A
= +25°C
T
A
= -40°C to +85°C
RST
Threshold
I
RST
= 1mA, V
OUT
= +2.5V
V
RST
= +5.5V
V
LX
= +5.5V
V
OUT
= 0, V
BATT
= V
SHDN
= V
LX
= -3V
V
BATT
= +2V, V
OUT
= +3.3V
V
BATT
= +2V, V
OUT
= +3.3V, I
LOAD
= 40mA
Note 1:
All units are 100% production tested at T
A
=+25°C. Limits over the operating temperature range are guaranteed by design
and not production tested.
Note 2:
Supply current into OUT. This current correlates directly to the actual battery-supply current, but is reduced in value accord-
ing to the step-up ratio and efficiency.
_______________________________________________________________________________________
3
High-Efficiency Step-Up Converters with
Reverse Battery Protection
MAX1832–MAX1835
Typical Operating Characteristics
(V
OUT
= +3.3V, V
BATT
= +2V, unless otherwise noted.) (Figure 1)
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 5.0V)
MAX1832/35 toc01
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 3.3V)
MAX1832/35 toc02
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 2.5V)
V
BATT
= +2.0V
80
MAX1832/35 toc03
95
90
EFFICIENCY (%)
85
80
75
70
65
0.1
1
10
I
LOAD
(mA)
100
V
BATT
= +1.5V
V
SHDN
= V
BATT
R1 = 309Ω
R2 = 100kΩ
MAX1834
V
BATT
= +2.7V
V
BATT
= +3.3V
95
85
90
EFFICIENCY (%)
V
BATT
= +2.7V
V
BATT
= +2.0V
85
V
BATT
= +1.5V
80
V
SHDN
= V
BATT
MAX1835
EFFICIENCY (%)
V
BATT
= +1.5V
75
V
SHDN
= V
BATT
R1 = 100kΩ
R2 = 100kΩ
C
IN
= 20µF
C
OUT
= 20µF
MAX1834
0.1
1
10
I
LOAD
(mA)
10
100
75
1000
0.1
1
10
I
LOAD
(mA)
70
100
1000
MAXIMUM OUTPUT CURRENT
vs. BATTERY VOLTAGE
MAX1832/35 toc04
STARTUP BATTERY VOLTAGE
vs. LOAD RESISTANCE
V
SHDN
= V
BATT
1.6
MAX1832/35 toc05
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (SHUTDOWN, NO LOAD)
1.2
1.0
0.8
I
BATT
(µA)
MAX1832/35 toc06
250
V
OUT
= +2.5V
200
V
OUT
= +3.3V
1.7
V
SHDN
= 0
R
LOAD
=
∞
MAX1833
V
OUT
6
5
4
3
2
V
OUT
(V)
V
OUT
(V)
I
LOAD
(mA)
V
BATT
(V)
150
1.5
V
OUT
= +5.0V
0.6
0.4
I
BATT
0.2
0
100
V
OUT
= +5.0V
1.4
V
OUT
= +3.3V
1.3
1
0
-1
-6 -5 -4 -3 -2 -1 0
1
2
3
4
5
6
V
BATT
(V)
50
0
1
2
3
4
5
6
V
BATT
(V)
1.2
V
OUT
= +2.5V
10
100
R
LOAD
(Ω)
1k
10k
-0.2
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (SHUTDOWN, LOADED)
300
250
200
I
BATT
(mA)
150
100
50
0
-50
-6 -5 -4 -3 -2 -1 0
1
2
3
4
5
6
V
BATT
(V)
I
BATT
MAX1832/35 toc07
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (ON, NO LOAD)
140
120
100
80
I
BATT
(µA)
MAX1832/35 toc08
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (ON, LOADED)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
I
BATT
(mA)
V
OUT
(V)
400
350
300
250
200
150
100
50
0
-50
-6 -5 -4 -3 -2 -1 0
1
2
3
4
5
6
V
BATT
(V)
I
BATT
MAX1832/35 toc09
V
SHDN
= 0
R
LOAD
= 22Ω
MAX1833
V
OUT
6
5
4
3
2
1
0
-1
V
OUT
(V)
R
LOAD
=
∞
V
OUT
R
LOAD
= 22Ω
V
OUT
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
-0.5
60
40
20
0
-20
-40
-6 -5 -4 -3 -2 -1 0
1
2
3
4
5
6
V
BATT
(V)
I
BATT
0
-0.5
4
_______________________________________________________________________________________
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