Maxim MAX1833ETT30-T High-efficiency step-up converters with reverse battery protection Datasheet

19-1802; Rev 1; 10/03
KIT
ATION
EVALU
LE
B
A
IL
A
AV
High-Efficiency Step-Up Converters with
Reverse Battery Protection
Features
♦ Reverse Battery Protection for DC-DC Converter
and Load
♦ Up to 90% Efficiency
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.
♦ Adjustable Output Voltage (MAX1832/MAX1834)
♦ 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
♦ Up to 150mA Output Current
♦ Tiny 6-Pin SOT23 Package
♦ Tiny 6-Pin Thin QFN Package (MAX1833ETT30)
________________________Applications
Ordering Information
Medical Diagnostic Equipment
Pagers
Hand-Held Instruments
Remote Wireless Transmitters
Digital Cameras
Cordless Phones
Battery Backup
PC Cards
Local 3.3V or 5V Supply
PART
TEMP RANGE
PINPACKAGE
TOP
MARK
MAX1832EUT-T
-40°C to +85°C
6 SOT23-6
AAOT
MAX1833EUT-T
-40°C to +85°C
6 SOT23-6
AAOU
MAX1833ETT30-T
-40°C to +85°C
6 TDFN-6
ABX
MAX1834EUT-T
-40°C to +85°C
6 SOT23-6
AAOV
MAX1835EUT-T
-40°C to +85°C
6 SOT23-6
AAOW
Pin Configurations
TOP VIEW
Selector Guide
PART
SHDN 1
6
MAX1832
5
BATT 2
MAX1834
(MAX1833EUT)
(MAX1835)
GND 3
4
SOT23
FB (RST)
SHDN 1
OUT
BATT 2
LX
GND 3
6
MAX1833ETT
RST
5
OUT
4
LX
MAX1832EUT-T
OUTPUT
VOLTAGE
OUTPUT VOLTAGE
IN SHUTDOWN
Adjustable
VBATT
MAX1833EUT-T
Fixed 3.3V
VBATT
MAX1833ETT30-T
Fixed 3.0V
VBATT
MAX1834EUT-T
Adjustable
VBATT - 0.7V
MAX1835EUT-T
Fixed 3.3V
VBATT - 0.7V
TDFN
3mm ✕ 3mm
________________________________________________________________ Maxim Integrated Products
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.
1
MAX1832–MAX1835
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 current. 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 battery to be used as a backup or real-time clock supply
when the converter is off (see Selector Guide).
MAX1832–MAX1835
High-Efficiency Step-Up Converters with
Reverse Battery Protection
ABSOLUTE MAXIMUM RATINGS
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
BATT, LX to GND.........................................................-6V to +6V
LX to OUT ....................................................................-6V to +1V
SHDN to GND..............................................-6V to (VOUT + 0.3V)
OUT, FB, RST TO GND ............................................-0.3V to +6V
LX Current ................................................................................1A
Continuous Power Dissipation (TA = +70°C)
6-Pin SOT23 (derate 9.1mW/°C above +70°C) ...........727mW
6-Pin 3mm ✕ 3mm TDFN (derate 24.4mW/°C
above +70°C) ............................................................1951mW
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, VOUT = +3.3V, VBATT = +2V, GND = 0, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
SYMBOL
Output Range
VOUT
Battery Input Range
VBATT
Startup Battery Input Voltage
VSU
CONDITIONS
MAX1832/MAX1834
RLOAD = 2.6kΩ
MAX1833EUT/
MAX1835EUT
Output Voltage
VOUT
MAX1833ETT30
TYP
V
1.5
5.5
V
TA = +25°C
1.22
1.24
TA = +25°C
3.225
TA = -40°C to +85°C
3.208
TA = +25°C
2.94
TA = -40°C to +85°C
2.925
TA = +25°C
1.208
TA = -40°C to +85°C
1.204
3.290
1.228
3.5
IFB
MAX1832/
MAX1834,
VFB = +1.3V
TA = +25°C
FB Input Bias Current
TA = -40°C to +85°C
4.0
0.4
TA = +25°C
P-Channel On-Resistance
RPCH
VOUT = +3.3V
ILX = 100mA
TA = +25°C
N-Channel Switch Current Limit
IMAX
Switch Maximum On-Time
tON
VOUT = +3.3V
3.355
3.06
1.248
1.252
TA = -40°C to +85°C
0.5
TA = -40°C to +85°C
1.2
1.3
0.73
435
TA = -40°C to +85°C
400
525
615
650
3.5
5
6.5
2
17
34
TA = -40°C to +85°C
0
VOUT = +3.3V
Quiescent Current into OUT
(Note 2)
VOUT = +3.5V,
VFB = +1.3V
Shutdown Current into OUT
VOUT = +3.5V, V SHDN = VFB = 0V
TA = +25°C
39
2.5
TA = -40°C to +85°C
7.0
8.0
0.05
_______________________________________________________________________________________
Ω
Ω
V
TA = +25°C
Synchronous Rectifier ZeroCrossing Current
V
nA
1.6
TA = +25°C
V
20
1.5
ILX = 100mA, PCH off, VOUT = +3.5V,
VFB = +1.3V
V
3.075
MAX1832/
MAX1834
VOUT = +3.3V
ILX = 100mA
1.5
3.372
3.0
VFB
RNCH
UNITS
5.5
TA = -40°C to +85°C
N-Channel On-Resistance
MAX
2.0
FB Trip Voltage
P-Channel Catch-Diode Voltage
2
MIN
1
mA
µs
mA
µA
µA
High-Efficiency Step-Up Converters with
Reverse Battery Protection
(V SHDN = +1.5V, VOUT = +3.3V, VBATT = +2V, GND = 0, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
0
10
µA
1.8
5.0
Reverse Battery Current into
OUT
VOUT = 0, VBATT = V SHDN = VLX = -3V
Quiescent Current into BATT
VOUT = +3.5V,
VFB = +1.3V
Shutdown Current into BATT
VOUT = +3.5V, VBATT = +2V, V SHDN = 0
0.001
1
µA
Reverse Battery Current into
BATT
VOUT = 0, VBATT = V SHDN = VLX = -3V
0.002
10
µA
SHDN Logic Low
VBATT = +1.5V to +5.5V
0.3
V
1.228
1.271
SHDN Threshold
Rising edge
TA = +25°C
TA = -40°C to +85°C
6.0
TA = +25°C
1.185
TA = -40°C to +85°C
1.170
SHDN Threshold Hysteresis
1.286
0.02
µA
V
V
SHDN Input Bias Current
VOUT = +5.5V, V SHDN = +5.5V, TA = +25°C
13
100
nA
SHDN Reverse Battery Current
VOUT = 0, VBATT = V SHDN = VLX = -3V
52
150
µA
2.980
3.110
RST Threshold
MAX1833EUT/
MAX1835EUT,
falling edge
MAX1833ETT30
RST Voltage Low
TA = +25°C
2.830
TA = -40°C to +85°C
2.800
TA = +25°C
2.580
TA = -40°C to +85°C
2.553
2.717
TA = +25°C
V RST = +5.5V
LX Leakage Current
VLX = +5.5V
LX Reverse Battery Current
VOUT = 0, VBATT = V SHDN = VLX = -3V
Maximum Load Current
ILOAD
TA = -40°C to +85°C
TA = +25°C
TA = -40°C to +85°C
V
2.836
2.863
I RST = 1mA, VOUT = +2.5V
RST Leakage Current
Efficiency
3.140
0.2
0.1
100
1
1
100
100
0.001
10
V
nA
nA
µA
VBATT = +2V, VOUT = +3.3V
150
mA
VBATT = +2V, VOUT = +3.3V, ILOAD = 40mA
90
%
Note 1: All units are 100% production tested at TA=+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 according to the step-up ratio and efficiency.
_______________________________________________________________________________________
3
MAX1832–MAX1835
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VOUT = +3.3V, VBATT = +2V, unless otherwise noted.) (Figure 1)
EFFICIENCY vs. LOAD CURRENT
(VOUT = 3.3V)
VBATT = +2.7V
75
VSHDN = VBATT
R1 = 309Ω
R2 = 100kΩ
MAX1834
VBATT = +1.5V
85
1
10
100
VBATT = +1.5V
VSHDN = VBATT
R1 = 100kΩ
R2 = 100kΩ
CIN = 20µF
COUT = 20µF
MAX1834
75
VSHDN = VBATT
MAX1835
75
0.1
80
80
65
70
1000
0.1
1
10
100
1000
0.1
1
10
10
100
ILOAD (mA)
ILOAD (mA)
ILOAD (mA)
MAXIMUM OUTPUT CURRENT
vs. BATTERY VOLTAGE
STARTUP BATTERY VOLTAGE
vs. LOAD RESISTANCE
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (SHUTDOWN, NO LOAD)
VSHDN = VBATT
1.6
IBATT (µA)
VBATT (V)
VOUT = +5.0V
1.5
VOUT = +5.0V
1.4
4
VOUT
3
0.6
2
0.4
IBATT
VOUT = +3.3V
0.2
1
0
0
1.3
0
VOUT = +2.5V
1.2
1
2
3
4
5
6
10
-1
-0.2
100
1k
-6 -5 -4 -3 -2 -1 0
10k
1
2
3
4
5
6
VBATT (V)
RLOAD (Ω)
VBATT (V)
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (SHUTDOWN, LOADED)
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (ON, NO LOAD)
INPUT CURRENT AND OUTPUT VOLTAGE
vs. BATTERY VOLTAGE (ON, LOADED)
120
4
200
VOUT
3
150
100
2
IBATT
1
50
0
0
-1
-50
-6 -5 -4 -3 -2 -1 0
1
VBATT (V)
2
3
4
5
6
IBATT (µA)
100
80
3.5
3.0
2.5
IBATT
2.0
VOUT
60
1.5
40
1.0
20
0.5
IBATT
0
-20
-6 -5 -4 -3 -2 -1 0
1
VBATT (V)
2
3
4
5
6
MAX1832/35 toc09
300
4.0
IBATT (mA)
140
5
MAX1832/35 toc08
VSHDN = VBATT
RLOAD = ∞
R3 = 1MΩ
R4 = 220kΩ
C1 = 10nF
VOUT (V)
160
6
VOUT (V)
250
MAX1832/35 toc07
VSHDN = 0
RLOAD = 22Ω
MAX1833
VSHDN = VBATT
V
= 3.3V
250 OUT
RLOAD = 22Ω
R3 = 1MΩ
200 R4 = 220kΩ
C1 = 10nF
150
6
5
IBATT
4
3
VOUT
100
2
50
1
0
0
0
-0.5
-50
-1
-6 -5 -4 -3 -2 -1 0
1
VBATT (V)
_______________________________________________________________________________________
2
3
4
5
6
VOUT (V)
50
300
6
5
0.8
150
100
1.0
MAX1832/35 toc06
VSHDN = 0
RLOAD = ∞
MAX1833
VOUT (V)
VOUT = +3.3V
1.2
MAX1832/35 toc05
VOUT = +2.5V
200
1.7
MAX1832/35 toc04
250
ILOAD (mA)
VBATT = +2.0V
VBATT = +1.5V
70
4
VBATT = +2.0V
EFFICIENCY (%)
EFFICIENCY (%)
EFFICIENCY (%)
85
80
VBATT = +2.7V
90
85
MAX1832/35 toc02
VBATT = +3.3V
90
95
MAX1832/35 toc01
95
EFFICIENCY vs. LOAD CURRENT
(VOUT = 2.5V)
MAX1832/35 toc03
EFFICIENCY vs. LOAD CURRENT
(VOUT = 5.0V)
IBATT (mA)
MAX1832–MAX1835
High-Efficiency Step-Up Converters with
Reverse Battery Protection
High-Efficiency Step-Up Converters with
Reverse Battery Protection in a SOT23-6
ON/OFF RESPONSE
LOAD TRANSIENT
MAX1832/35 toc10
MAX1832/35 toc11
VBATT
1V/div
VOUT
100mV/div
VOUT
1V/div
ILOAD
100mA/div
0
2ms/div
VSHDN = VBATT = 2.0V, RLOAD = 22Ω,
VOUT = 3.3V
40µs/div
RLOAD = 22Ω TO 200Ω,
VOUT = +3.3V, VBATT = +2.0V
SHUTDOWN RESPONSE
LINE TRANSIENT
MAX1832/35 toc13
MAX1832/35 toc12
VSHDN
1V/div
VBATT
500mV/div
0
VOUT
1V/div
VOUT
50mV/div
0
MAX1833
40µs/div
RLOAD = 22Ω, VBATT = 3.3V, VBATT = 2.0V
40µs/div
IOUT = 100mA, VOUT = +3.3V,
VBATT = +2.0V TO +2.5V
SWITCHING WAVEFORMS
MAX1832/35 toc14
VLX
500mA/div
VOUT
100mV/div
VLX
2V/div
10µs/div
IOUT = 40mA, VOUT = +3.3V, VBATT = +2.0V
_______________________________________________________________________________________
5
MAX1832–MAX1835
Typical Operating Characteristics (continued)
(VOUT = +3.3V, VBATT= +2V, unless otherwise noted.) (Figure 1)
High-Efficiency Step-Up Converters with
Reverse Battery Protection
MAX1832–MAX1835
Pin Description
PIN
MAX1832
MAX1834
NAME
MAX1833
MAX1835
FUNCTION
1
1
SHDN
Shutdown. A high logic level turns on the device. When SHDN is low the part is off,
and the current into BATT is typically 0.1µA. For the MAX1832/MAX1833, the
battery is connected to OUT through an internal PFET and the external inductor
when SHDN is low. SHDN can be used for low-battery cutoff (1.228V threshold).
See Low-Battery Cutoff. SHDN has reverse battery protection.
2
2
BATT
Battery Voltage Connection. BATT has reverse battery protection.
3
3
GND
Ground
4
4
LX
5
5
OUT
6
—
FB
—
6
RST
Inductor Connection. N-channel MOSFET switch drain and synchronous
rectifier P-channel switch drain. LX has reverse battery protection.
Output Voltage. Bootstrapped supply for the device. Output sense point for
MAX1833/MAX1835.
MAX1832/MAX1834 Feedback Input. Set the output voltage through a
resistor-divider network. See Setting the Output Voltage.
MAX1833/MAX1835 Power-On Reset Open-Drain Output. RST pulls low when
the output is 10% below the regulation point. If not used, connect to GND.
+1.5V TO +3.3V
BATTERY
10µF
+1.5V TO +5.0V
BATTERY
10µF
10µH
LX
R4
220kΩ
R3
1MΩ
BATT
100kΩ
MAX1833
MAX1835
C1
10nF
RST
SHDN
OUTPUT
+3.3V
10µF
OUT
LX
R4
220kΩ
POWER-ON
RESET
Figure 1a. MAX1833/MAX1835 Typical Operating Circuit
BATT
OUTPUT
+5.0V
OUT
R2
309kΩ
MAX1832
MAX1834
FB
SHDN
R3
1MΩ
GND
6
10µH
C1
10nF
GND
R1
100kΩ
Figure 1b. MAX1832/MAX1834 Typical Operating Circuit
_______________________________________________________________________________________
High-Efficiency Step-Up Converters with
Reverse Battery Protection
The MAX1832–MAX1835 compact, high-efficiency
step-up converters feature 4µA quiescent supply current to ensure the highest possible efficiency over a
wide load range. With a minimum +1.5V input voltage,
these devices are well suited for applications with two
alkaline cells, two nickel-metal-hydride (NiMH) cells, or
one lithium ion (Li+) cell. For the MAX1832 and
MAX1833, the battery is connected to OUT through the
inductor and an internal PFET when SHDN is low. This
allows the input battery to be used as a backup or realtime clock supply when the converter is off by eliminating the voltage drop across the PFET body diode.
The MAX1832–MAX1835 are ideal for low-power applications where ultra-small size is critical. These devices
feature built-in synchronous rectification that significantly improves efficiency and reduces size and cost
by eliminating the need for an external Schottky diode.
Furthermore, these devices are the industry’s first boost
regulators to offer complete reverse battery protection.
This proprietary design protects the battery, IC, and the
circuitry powered by the IC in the event the input batteries are connected backwards.
Control Scheme
A current-limited control scheme is a key feature of the
MAX1832–MAX1835. This scheme provides ultra-low
quiescent current and high efficiency over a wide output current range. There is no oscillator. The inductor
current is limited by the 0.5A N-channel current limit or
by the 5µs switch maximum on-time. Following each
on-cycle, the inductor current must ramp to zero before
another cycle may start. When the error comparator
senses that the output has fallen below the regulation
threshold, another cycle begins.
An internal synchronous rectifier eliminates the need for
an external Schottky diode reducing cost and board
space. While the inductor discharges, the P-channel
MOSFET turns on and shunts the MOSFET body diode.
As a result, the rectifier voltage drop is significantly
reduced, improving efficiency without adding external
components.
Reverse Battery Protection
The MAX1832–MAX1835 have a unique proprietary
design that protects the battery, IC, and circuitry powered by the IC in the event that the input batteries are
connected backwards. When the batteries are connected correctly, the reverse battery protection N-channel
MOSFET is on and the device operates normally.
When the batteries are connected backwards, the
reverse battery protection N-channel MOSFET opens,
protecting the device and load (Figures 2 and 3).
Previously, this level of protection required additional
circuitry and reduced efficiency due to added components in the battery current path.
Applications Information
Shutdown
When SHDN is low, the device is off and no current is
drawn from the battery. When SHDN is high, the device
is on. If SHDN is driven from a logic-level output, the
logic high (on) level should be referenced to VOUT to
avoid intermittent turn on. If SHDN is not used at all,
connect it to OUT. With SHDN connected to OUT, the
MAX1834/MAX1835 startup voltage (1.65V) is slightly
higher, due to the voltage across the PFET body diode.
The SHDN pin has reverse battery protection.
In shutdown, the MAX1832/MAX1833 connect the battery input to the output through the inductor and the
internal synchronous rectifier PFET. This allows the input
battery (rather than a separate backup battery) to provide backup power for devices such as an idled microcontroller, SRAM, or real-time clock, without the usual
diode forward drop. If the output has a residual voltage
during shutdown, a small amount of energy will be
transfered from the output back to the input immediately
after shutdown. This energy transfer may cause a slight
momemntary “bump” in the input voltage. The magnitude and duration of the input bump are related to the
ratio of CIN and COUT and the ability of the input to sink
current. With battery input sources, the bump will be
negligible, but with power-supply inputs (that typically
cannot sink current), the bump may be 100s of mV.
In shutdown, the MAX1834/MAX1835 do not turn on the
internal PFET and thus do not have an output-to-input
current path in shutdown. This allows a separate backup battery, such as a Li+ cell, to be diode-connected at
the output, without leakage current flowing to the input.
The MAX1834/MAX1835 still have the typical input-tooutput current path from the battery to the output,
through the PFET body diode, in shutdown.
Low-Battery Cutoff
The SHDN trip threshold of the MAX1832–MAX1835
can be used as a voltage detector, with a resistordivider, to power down the IC when the battery voltage
falls to a set level (Figure 1). The SHDN trip threshold is
1.228V. To use a resistor-divider to set the shutdown
voltage, select a value for R3 in the 100kΩ to 1MΩ
range to minimize battery drain. Calcuate R4 as follows:
R4 = R3 ✕ (VOFF / VSHDN - 1)
VOFF is the battery voltage at which the part will shut
down and VSHDN = 1.228V. Note that input ripple can
_______________________________________________________________________________________
7
MAX1832–MAX1835
Detailed Description
MAX1832–MAX1835
High-Efficiency Step-Up Converters with
Reverse Battery Protection
OUT
STARTUP
CIRCUITRY
ZEROCROSSING
DETECTOR
MAX1832
MAX1834
P
SHDN
CONTROL
LOGIC
LX
DRIVER
FB
N
ERROR
COMPARATOR
BATT
REVERSE BATTERY
N
PROTECTION MOSFET
CURRENT
LIMIT
1.228V
GND
Figure 2. MAX1832/MAX1834 Simplified Functional Diagram
OUT
MAX1833
MAX1835
STARTUP
CIRCUITRY
ZEROCROSSING
DETECTOR
P
CONTROL
LOGIC
N
1.228V
REVERSE BATTERY N
PROTECTION MOSFET
RST
N
LX
DRIVER
ERROR
COMPARATOR
BATT
CURRENT
LIMIT
RESET
GND
1.1V
SHDN
Figure 3. MAX1833/MAX1835 Simplified Functional Diagram
8
_______________________________________________________________________________________
High-Efficiency Step-Up Converters with
Reverse Battery Protection
Table 1. Suggested Inductors and
Suppliers
MANUFACTURER
INDUCTOR
PHONE
Coilcraft
DS1608C-103
DO1606T-103
847-639-6400
Sumida
CDRH4D18-100
CR43-100
847-956-0666
Murata
LQH4N100K
814-237-1431
Power-On Reset
The MAX1833/MAX1835 provide a power-on reset output (RST). A 100kΩ to 1MΩ pullup resistor from RST to
OUT provides a logic control signal. This open-drain
output pulls low when the output is 10% below its regulation point. If not used, connect it to GND.
Setting the Output Voltage
The output voltage of the MAX1832/MAX1834 is
adjustable from +2V to +5.5V, using external resistors
R1 and R2 (Figure 1b). Since FB leakage is 20nA
(max), select feedback resistor R1 to be 100kΩ to
1MΩ. Calculate R2 as follows:
V

R2 = R1  OUT − 1
 VFB

Table 2. Suggested Surface-Mount
Capacitors and Manufacturers
VALUE
(µF)
DESCRIPTION
MANUFACTURER
PHONE
594/595 Dseries tantalum
Sprague
603-224-1961
TAJ, TPSseries tantalum
AVX
803-946-0690
4.7 to
10
X7R ceramic
TDK
847-390-4373
4.7 to
22
X7R ceramic
Taiyo Yuden
408-573-4150
4.7 to
47
where VFB = 1.228V.
Inductor Selection
The control scheme of the MAX1832–MAX1835 permits
flexibility in choosing an inductor. A 10µH inductor performs well for most applications, but values from 4.7µH to
100µH may also be used. Small inductance values typically offer smaller physical size. Large inductance values
minimize output ripple but reduce output power. Output
power is reduced when the inductance is large enough
to prevent the maximum current limit (525mA) from being
reached before the maximum on-time (5µs) expires.
For maximum output current, choose L such that:
VBATT(MAX) (1µs)
0.525A
IOUT(MAX) = 0.525A ×
2
<L <
VBATT(MIN) (5µs)
VBATT(MIN) −
0.525A
0.525A
(RNCH + RIND )
2
VOUT
where RIND is the inductor series resistance, and RNCH
is the RDS(ON) of the N-channel MOSFET (0.4Ω typ).
Capacitor Selection
reduces the peak current drawn from the battery and
can be the same value as the input capacitor. A larger
input capacitor can be used to further reduce ripple and
improve efficiency.
PC Board Layout and Grounding
Careful printed circuit layout is important for minimizing
ground bounce and noise. Keep the IC’s GND pin and
the ground leads of the input and output filter capacitors less than 0.2in (5mm) apart. In addition, keep all
connections to the FB and LX pins as short as possible.
In particular, when using external feedback resistors,
locate them as close to FB as possible. To maximize
output power and efficiency and minimize output ripple
voltage, use a ground plane and solder the IC’s GND
directly to the ground plane.
Choose an output capacitor to achieve the desired output ripple percentage.
COUT >
0.5 × L × 0.525A
r% × VOUT 2
2
MAX1832–MAX1835
sometimes cause false shutdowns. To minimize the effect
of ripple, connect a low-value capacitor (C1) from SHDN
to GND to filter out input noise. Select a C1 value such
that the R4 ✕ C1 time constant is above 2ms.
Chip Information
TRANSISTOR COUNT: 953
PROCESS: BiCMOS
where r is the desired output ripple in %. A 10µF ceramic
capacitor is a good starting value. The input capacitor
_______________________________________________________________________________________
9
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
6LSOT.EPS
MAX1832–MAX1835
High-Efficiency Step-Up Converters with
Reverse Battery Protection
PACKAGE OUTLINE, SOT-23, 6L
21-0058
10
______________________________________________________________________________________
F
1
1
High-Efficiency Step-Up Converters with
Reverse Battery Protection
6, 8, &10L, QFN THIN.EPS
L
A
D
D2
A2
PIN 1 ID
1
N
1
C0.35
b
E
PIN 1
INDEX
AREA
[(N/2)-1] x e
REF.
E2
DETAIL A
e
k
A1
CL
CL
L
L
e
e
A
DALLAS
SEMICONDUCTOR
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 6, 8 & 10L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY
APPROVAL
DOCUMENT CONTROL NO.
21-0137
REV.
D
1
2
______________________________________________________________________________________
11
MAX1832–MAX1835
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
MAX1832–MAX1835
High-Efficiency Step-Up Converters with
Reverse Battery Protection
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
COMMON DIMENSIONS
SYMBOL
A
MIN.
MAX.
0.70
0.80
D
2.90
3.10
E
2.90
3.10
A1
0.00
0.05
L
k
0.20
0.40
0.25 MIN.
A2
0.20 REF.
PACKAGE VARIATIONS
PKG. CODE
N
D2
E2
e
JEDEC SPEC
b
T633-1
6
1.50–0.10
2.30–0.10
0.95 BSC
MO229 / WEEA
0.40–0.05
1.90 REF
T833-1
8
1.50–0.10
2.30–0.10
0.65 BSC
MO229 / WEEC
0.30–0.05
1.95 REF
T1033-1
10
1.50–0.10
2.30–0.10
0.50 BSC
MO229 / WEED-3
0.25–0.05
2.00 REF
[(N/2)-1] x e
DALLAS
SEMICONDUCTOR
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 6, 8 & 10L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
APPROVAL
DOCUMENT CONTROL NO.
21-0137
REV.
D
2
2
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.
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Printed USA
is a registered trademark of Maxim Integrated Products.