_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
General Description
The MAX16914/MAX16915 low-quiescent-current over-
voltage and reverse-battery protection controllers are
designed for automotive and industrial systems that
must tolerate high-voltage transient and fault conditions.
These conditions include load dumps, voltage dips, and
reversed input voltages. The controllers monitor the input
voltage on the supply line and control two external pFETs
to isolate the load from the fault condition. The external
pFETs are turned on when the input supply exceeds
4.5V and stay on up to the programmed overvoltage
threshold. During high-voltage fault conditions, the con-
trollers regulate the output voltage to the set upper
threshold voltage (MAX16915), or switch to high resis-
tance (MAX16914) for the duration of the overvoltage
transient to prevent damage to the downstream circuitry.
The overvoltage event is indicated through an active-low,
open-drain output, OV.
The reverse-battery pFET behaves as an ideal diode,
minimizing the voltage drop when forward biased. Under
reverse bias conditions, the pFET is turned off, prevent-
ing a downstream tank capacitor from being discharged
into the source.
Shutdown control turns off the IC completely, discon-
necting the input from the output and disconnecting
TERM from its external resistor-divider to reduce the
quiescent current to a minimum.
Both devices are available in a 10-pin FMAXM package
and operate over the automotive -40NC to +125NC tem-
perature range.
Applications
Automotive
Industrial
Features
S 4.5V to 19V Input Voltage Operation
S Transient Voltage Protection Up to +44V and -75V
S Adjustable Overvoltage Limit with Resistor-
Divider Shut Off in Shutdown
S Ideal Diode Reverse-Battery Protection
S Low Voltage Drop When Used with Properly Sized
External pFETs
S Back-Charge Prevention
S Overvoltage Indicator
S Shutdown Input
S 29µA Low Operating Current
S 6µA Low Shutdown Current
S Thermal-Overload Protection
S -40NC to +125NC Operating Temperature Range
S Small 10-Pin µMAX Package
S AEC-Q100 Qualified
19-4964; Rev 0; 9/09
Pin Configuration
Typical Operating Circuit
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified device.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
1
+
2
3
4
5
10
9
8
7
6
GATE2
SENSE OUT
TERM
SETSHDN
SENSE IN
GATE1
VCC
MAX16914
MAX16915
TOP VIEW
GNDOV
VCC
VBATT VOUT
P2P1
GATE1
SENSE IN
R1
R2
SHDN
ON
OFF
MAX16914
MAX16915
GATE2
SENSE OUT
OV
TERM
SET
GND
OV
PART TEMP RANGE PIN-PACKAGE
MAX16914AUB/V+ -40NC to +125NC 10 FMAX
MAX16915AUB/V+ -40NC to +125NC 10 FMAX
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
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.
VCC, SENSE OUT, TERM, SHDN, OV to GND for
P 400ms .............................................................-0.3V to +44V
VCC, SENSE OUT, TERM, SHDN, OV to GND
for P 90s .............................................................-0.3V to +28V
VCC, SENSE OUT, TERM, SHDN, OV to GND .....-0.3V to +20V
SENSE IN to GND for P 2ms ..................................-75V to +44V
SENSE IN to GND for P 90s ..................................-18V to +44V
SENSE IN to GND .................................................-0.3V to +20V
GATE1, GATE2 to VCC ..........................................-16V to +0.3V
GATE1, GATE2 to GND ........................... -0.3V to (VCC + 0.3V)
SET to GND .............................................................-0.3V to +8V
Continuous Power Dissipation (TA = +70NC)
10-Pin FMAX (derate 8.8mW/NC above TA = +70NC)
(Note 1) .......................................................................707mW
Operating Temperature Range ........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range ............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
ELECTRICAL CHARACTERISTICS
(VCC = 14V, CGATE1 = 32nF, CGATE2 = 32nF, SHDN = high, TA = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = +25NC.) (Note 2)
ABSOLUTE MAXIMUM RATINGS
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.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Voltage Range VCC (Note 3) 4.5 19 V
Shutdown Supply Current
(ISENSE IN + ISENSE OUT + IOV +
ISHDN + IVCC)
ISHDN
SHDN = low,
VSENSE OUT = 0V,
VTERM = 0V
TA = +25NC 6.0 12
FA
TA = +85NC (Note
3) 6.1 12
TA = +125NC
(Note 3) 6.2 12
Quiescent Supply Current
(ISENSE IN + ISENSE OUT + IOV +
ISHDN + IVCC)
IQSHDN = high
TA = +25NC 29 53
FA
TA = +85NC (Note
3) 30 55
TA = +125NC
(Note 3) 31 57
VCC Undervoltage Lockout VUVLO VCC rising, VSET = 1V , SHDN = high 4.06 4.35 V
VCC Undervoltage-Lockout
Hysteresis 8 %
SET Threshold Voltage VSETTH VSET rising -3% +1.20 +3% V
SET Threshold Voltage
Hysteresis VSETHY 4 %
SET Input Current ISET VSET = 1V 0.02 0.2 FA
SHDN Low Threshold VSHDNL 0.4 V
SHDN High Threshold VSHDNH 1.4 V
SHDN Pulldown Current ISHDN VSHDN = 14V, internally pulled to GND 0.5 1.0 FA
VCC to GATE Output Low
Voltage VGVCC1 VCC = 14V 6.25 7.5 8.5 V
VCC to GATE Clamp Voltage VGVCC2 VCC = 42V 14 V
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 14V, CGATE1 = 32nF, CGATE2 = 32nF, SHDN = high, TA = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = +25NC.) (Note 2)
Note 2: All parameters are production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by
design and characterization.
Note 3: Guaranteed by design and characterization.
Note 4: The back-charge voltage, VBC, is defined as the voltage at SENSE OUT minus the voltage at SENSE IN.
Note 5: Defined as the time from when VBC exceeds VBCTH (25mV typ) to when VGATE1 exceeds VCC - 3.5V.
Note 6: Defined as the time from when VBC falls below VBCTH - 50mV to when VGATE1 falls below VCC - 3.5V.
Note 7: Defined as the time from when VSET exceeds VSETTH (1.20V typ) to when VGATE2 exceeds VCC - 3.5V.
Note 8: Defined as the time from when VSET falls below VSETTH - 5% (1.14V typ) to when VGATE2 falls below VCC - 3.5V.
Note 9: The external pFETs can turn on tSTART after the IC is powered up and all input conditions are valid.
Note 10: Defined as the time from when VCC exceeds the undervoltage-lockout threshold (4.3V max) to when VGATE1 and VGATE2
fall below 1V.
Note 11: Defined as the time from when VCC falls below VSENSE OUT - 25mV to when VGATE1 reaches VCC - 1.75V.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TERM On-Resistance RTERM SHDN = high 150 500 I
TERM Output Current ITERM SHDN = low, VTERM = 0V 1.0 FA
Back-Charge Voltage Fault
Threshold VBCTH VSENSE OUT = 14V (Note 4) 18 25 32 mV
Back-Charge Voltage Threshold
Hysteresis VBCHY VSENSE OUT = 14V 50 mV
Back-Charge Turn-Off Time
(GATE1) tBC
VCC = 9.5V, VSENSE IN = 9V,
VSENSE OUT stepped from 4.9V to 9.5V
(Note 5)
6 10 Fs
Back-Charge Recovery Time
(GATE1) tBCREC
VCC = 9.5V, VSENSE IN = 9V,
VSENSE OUT stepped from 9.5V to 4.9V
(Note 6)
18 30 Fs
GATE2 Turn-Off Time VCC = 9.5V, VSET rising from 1V to
1.5V (Note 7) 3Fs
GATE2 Turn-On Time VCC = 9.5V, VSET falling from 1.5V to
1V (Note 8) 20 Fs
Startup Response Time
(VSHDN Rising) tSTART1 VCC = 9.5V, from VSHDN rising to
VGATE_ falling (Note 9) 100 Fs
Startup Response Time
(VCC Rising) tSTART2 VCC rising from 2V to 4.5V, SHDN =
high (Note 10) 0.150 ms
Reverse-Battery Voltage Turn-Off
Time/UVLO Turn-Off Time tREVERSE
VCC and VSENSE IN falling from 4.25V
to 3.25V, VSENSE OUT = 4.25V
(Note 11)
30 Fs
Thermal-Shutdown Temperature +170 NC
Thermal-Shutdown Hysteresis 20 NC
OV Output Low Voltage VOVBL ISINK = 600FA 0.4 V
OV Open-Drain Leakage Current IOVB VSET = 1.0V 1.0 FA
SENSE IN Input Current ISENSE IN VSHDN = 0/14V 1 5 FA
SENSE OUT Input Current ISENSE OUT VSHDN = 0/14V 2 5 FA
SET to OV Output Low
Propagation Delay tOVBPD VCC = 9.5V, VSET rising from 1V to
1.5V to VOV falling 3Fs
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
4 ______________________________________________________________________________________
Typical Operating Characteristics
(VCC = 14V, VSHDN = 14V, MAX16914/MAX16915 Evaluation Kit, TA = +25NC, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX16914 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
17.012.0 14.59.57.0
15
20
25
30
10
4.5 19.0
TERM = OPEN
SHDN = HIGH
SET = 0V
NO LOAD
MAX16914
MAX16915
SUPPLY CURRENT
vs. TEMPERATURE
MAX16914 toc02
TEMPERATURE (NC)
SUPPLY CURRENT (FA)
11085603510-15
15
20
25
30
35
40
10
-40 125
TERM = OPEN
SHDN = HIGH
SET = 0V, VCC = 14V
NO LOAD
MAX16915
MAX16914
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX16914 toc03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (FA)
17.014.512.09.57.0
2
4
6
8
10
0
4.5 19.0
SHDN = LOW
SET = 0V
MAX16915
MAX16914
UVLO THRESHOLD
vs. TEMPERATURE
MAX16914 toc04
TEMPERATURE (NC)
UVLO TRESHOLD (V)
11085-15 10 35 60
3.6
3.7
3.8
3.9
4.0
4.1
4.2
4.3
3.5
-40 125
RISING
FALLING
SET THRESHOLD
vs. TEMPERATURE
MAX16914 toc05
TEMPERATURE (NC)
SET THRESHOLD (V)
11085603510-15
1.15
1.20
1.25
1.10
-40 125
RISING
FALLING
POWER-UP RESPONSE
MAX16914 toc06
40µs/div
VCC
10V/div
VOUT
10V/div
VGATE1
10V/div
VGATE2
10V/div
22µF INPUT AND OUTPUT CAPACITOR,
ROUT = 100I, SHDN = HIGH
STARTUP FROM
SHUTDOWN RESPONSE
MAX16914 toc07
20µs/div
100µF INPUT CAPACITOR, 122µF
OUTPUT CAPACITOR, ROUT = 100I
VSHDN
2V/div
VOUT
10V/div
VGATE1
10V/div
14V
14V
0V
0V
VGATE2
10V/div
OVERVOLTAGE LIMITER RESPONSE
(MAX16915)
MAX16914 toc08
400µs/div
100µF INPUT CAPACITOR, 22µF
OUTPUT CAPACITOR, ROUT = 100I
COV = 10nF
VCC = 14V TO 30V
TRIP THRESHOLD = 22V
VCC
20V/div
VOUT
20V/div
0V
14V
14V
14V
30V
VGATE2
20V/div
VOV
20V/div
OVERVOLTAGE SWITCH-OFF
RESPONSE (MAX16914)
MAX16914 toc09
1.0µs/div
100µF INPUT CAPACITOR, 22µF
OUTPUT CAPACITOR, ROUT = 100I
VCC
10V/div
VOUT
10V/div
14V
30V
30V
14V
14V
0V
0V
20V
VGATE2
20V/div
VOV
20V/div
VCC = 14V TO 30V
TRIP THRESHOLD = 22V
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VCC = 14V, VSHDN = 14V, MAX16914/MAX16915 Evaluation Kit, TA = +25NC, unless otherwise noted.)
Pin Description
PIN NAME FUNCTION
1 VCC Positive Supply Input Voltage. Bypass VCC to GND with a 0.1FF or greater ceramic capacitor.
2 GATE1 Gate-Driver Output. Connect GATE1 to the gate of an external p-channel FET pass switch to pro-
vide low drain-to-source voltage drop, reverse voltage protection, and back-charge prevention.
3 SENSE IN Differential Voltage Sense Input (Input Side of IC). Used with SENSE OUT to provide back-charge
prevention when the SENSE IN voltage falls below the SENSE OUT voltage by 25mV.
4SHDN
Active-Low Shutdown/Wake Input. Drive SHDN high to turn on the voltage detectors. GATE2 is
shorted to VCC when SHDN is low. SHDN is internally pulled to GND through a 0.5FA current sink.
Connect SHDN to VCC for always-on operation.
5OV Open-Drain Overvoltage Indicator Output. Connect a pullup resistor from OV to a positive supply
such as VCC. OV is pulled low when the voltage at SET exceeds the internal threshold.
6 GND Ground
7 SET
Controller Overvoltage Threshold Programming Input. Connect SET to the center of an external
resistive divider network between TERM and GND to adjust the desired overvoltage switch-off or
limiter threshold.
8 TERM
Voltage-Divider Termination Output. TERM is internally connected to SENSE OUT in the MAX16915
and to VCC in the MAX16914. TERM is high impedance when SHDN is low, forcing the current to
zero in the resistor-divider connected to TERM.
9 SENSE OUT Differential Voltage Sense Input (Output Side Of IC). Used with SENSE IN to provide back-charge
prevention when the SENSE IN voltage falls below the SENSE OUT voltage by 25mV.
10 GATE2
Gate-Driver Output. Connect GATE2 to the gate of an external p-channel FET pass switch. GATE2
is driven low during normal operation and quickly regulated or shorted to VCC during an overvolt-
age condition. GATE2 is shorted to VCC when SHDN is low.
BACK-CHARGE RESPONSE
MAX16914 toc10
1.0µs/div
2.2µF INPUT CAPACITOR, 400I
INPUT RESISTOR, 22µF OUTPUT CAPACITOR
VCC
5V/div
VOUT
5V/div
0V
5V
5V
VGATE1
5V/div
VCC - VGATE_
vs. INPUT VOLTAGE
MAX16914 toc11
SUPPLY VOLTAGE (V)
GATE DRIVE VOLTAGE (V)
40.536.027.0 31.513.5 18.0 22.59.0
1.5
3.0
4.5
6.0
7.5
9.0
10.5
12.0
13.5
15.0
0
4.5 44.0
GATE1
GATE2
SET = GND
SHDN = HIGH
GATE-DRIVE VOLTAGE
vs. TEMPERATURE
MAX16914 toc12
TEMPERATURE (NC)
GATE-DRIVE VOLTAGE (V)
11085603510-15
6.3
6.4
6.5
6.6
6.2
-40 125
GATE1
GATE2
VCC = 14V
SET = GND
SHDN = HIGH
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
6 ______________________________________________________________________________________
Detailed Description
The MAX16914/MAX16915 are ultra-small, low-quies-
cent, high load-current, overvoltage-protection circuits
for automotive or industrial applications. These devices
monitor the input and output voltages and control two
p-channel MOSFETs to protect downstream loads from
reverse-battery, overvoltage, and high-voltage transient
conditions and prevent downstream tank capacitors
from discharging into the source (back-charging).
One MOSFET (P1) eliminates the need for external
diodes, thus minimizing the input voltage drop and
provides back-charge and reverse-battery protection.
The second MOSFET (P2) isolates the load or regulates
the output voltage during an overvoltage condition.
These ICs allow system designers to size the external
p-channel MOSFET to their load current, voltage drop,
and board size.
Overvoltage Switch-Off Controller
(MAX16914)
In the MAX16914, the input voltage is monitored (TERM
is internally shorted to VCC—see the Functional Diagram)
making the device an overvoltage switch-off controller.
As the VCC voltage rises, and the programmed overvolt-
age threshold is tripped, the internal fast comparator
turns off the external p-channel MOSFET (P2), pulling
GATE2 to VCC to disconnect the power source from
the load. When the monitored voltage goes below the
adjusted overvoltage threshold, the MAX16914 enhanc-
es GATE2, reconnecting the load to the power source.
Functional Diagram
REG
GATE2
1.20V
GATE1
SENSE IN
SHDN
OV
VCC
SENSE OUT
SET
TERM
GND
TERM
SWITCH
TO VCC FOR
MAX16914
TO SENSE OUT
FOR MAX16915
BANDGAP
BIAS
OV1
OV1
MAX16914
MAX16915
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
_______________________________________________________________________________________ 7
Overvoltage Limiter
Controller (MAX16915)
In the MAX16915, TERM is internally connected to
SENSE OUT (see the Functional Diagram) allowing the
IC to operate in voltage-limiter mode.
During normal operation, GATE2 is pulled low to fully
enhance the MOSFET. The external MOSFET’s drain
voltage is monitored through a resistor-divider between
TERM, SET, and GND. When the output voltage rises
above the adjusted overvoltage threshold, an internal
comparator pulls GATE2 to VCC turning off P2. When
the monitored voltage goes below the overvoltage
threshold (-4% hysteresis), the p-channel MOSFET (P2)
is turned on again. During a continuous overvoltage
condition, MOSFET (P2) cycles on and off (between the
overvoltage threshold and the hysteresis), generating a
sawtooth waveform with a frequency dependent on the
load capacitance and load current. This process contin-
ues to keep the voltage at the output regulated to within
approximately a 4% window. The output voltage is regu-
lated during the overvoltage transients and MOSFET
(P2) continues to conduct during the overvoltage event,
operating in switched-linear mode.
Caution must be exercised when operating the
MAX16915 in voltage-limiting mode for long durations
due to the MOSFET’s power-dissipation consideration
(see the MOSFET Selection section).
Shutdown
The MAX16914/MAX16915 feature an active-low shut-
down input (SHDN). Drive SHDN low to switch off FET
(P2), disconnecting the input from the output, thus
placing the IC in low-quiescent-current mode. Reverse-
battery protection is still maintained.
Reverse-Battery Protection
The MAX16914/MAX16915 feature reverse-battery pro-
tection to prevent damage to the downstream circuitry
caused by battery reversal or negative transients. The
reverse-battery protection blocks the flow of current into
the downstream load and allows the circuit designer to
remove series-protection diodes.
Back-Charge Switch-Off
The MAX16914/MAX16915 monitor the input-to-output
differential voltage between SENSE IN and SENSE OUT.
It turns off the external FET (P1) when (VSENSE OUT -
VSENSE IN) > 25mV (see Figure 1) to prevent discharg-
ing of a downstream tank capacitor into the battery sup-
ply during an input voltage drop, such as a cold-crank
condition or during a superimposed sinusoidal voltage
on top of the supply voltage. It turns on the FET (P1)
again if the back-charge voltage threshold hysteresis of
50mV is satisfied.
Figure 1. Back-Charge Turn-Off Time
IOUT
VOUT - VBATT = 0V
VOUT - VBATT = 50mV
tBC = 10µs (max)
VBATT = 9V
50% (25mV)
50%
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
8 ______________________________________________________________________________________
Overvoltage Indicator Output (OV)
The MAX16914/MAX16915 include an active-low,
open-drain overvoltage-indicator output (OV). For the
MAX16914, OV asserts low when VCC exceeds the pro-
grammed overvoltage threshold. OV deasserts when the
overvoltage condition is over.
For the MAX16915, OV asserts if VOUT exceeds the
programmed overvoltage threshold. OV deasserts when
VOUT drops 4% (typ) below the overvoltage threshold
level. If the overvoltage condition continues, OV may
toggle with the same frequency as the overvoltage limiter
FET (P2). If the P2 device is turned on for a very short
period (less than tOVBPD), the OV pin may not toggle.
To obtain a logic-level output, connect a 45kI pullup
resistor from OV to a system voltage less than 44V. A
capacitor connected from OV to GND helps extend the
time that the logic level remains low.
Applications Information
Load Dump
Most automotive applications run off a multicell “12V”
lead-acid battery with a nominal voltage that swings
between 9V and 16V (depending on load current, charg-
ing status, temperature, battery age, etc.). The battery
voltage is distributed throughout the automobile and is
locally regulated down to voltages required by the differ-
ent system modules. Load dump occurs when the alter-
nator is charging the battery and the battery becomes
disconnected. The alternator voltage regulator is tem-
porarily driven out of control. Power from the alternator
flows into the distributed power system and elevates the
voltage seen at each module. The voltage spikes have
rise times typically greater than 5ms and decays within
several hundred milliseconds but can extend out to 1s
or more depending on the characteristics of the charg-
ing system. These transients are capable of destroying
sensitive electronic equipment on the first “fault event.”
Setting Overvoltage Thresholds
TERM and SET provide an accurate means to set the
overvoltage level for the MAX16914/MAX16915. Use a
resistive divider to set the desired overvoltage condition
(see the Typical Operating Circuit). VSET has a rising
1.20V threshold with a 4% falling hysteresis. Begin by
selecting the total end-to-end resistance:
RTOTAL = R1 + R2
For high accuracy, choose RTOTAL to yield a total cur-
rent equivalent to a minimum 100 x ISET where ISET is the
input bias current at SET.
For example:
With an overvoltage threshold (VOV) set to 20V, RTOTAL
< 20V/(100 x ISET), where ISET = 1FA (max).
RTOTAL < 200kI
Use the following formula to calculate R2:
R2 = (VTH x RTOTAL)/VOV
where VTH is the 1.20V SET rising threshold and VOV is
the desired overvoltage threshold.
Then, R2 = 12.0kI.
Use the nearest standard-value resistor lower than the
calculated value. A lower value for total resistance dissi-
pates more power but provides slightly better accuracy.
To determine R1:
RTOTAL = R2 + R1
Then, R1 = 188kI.
Use the nearest standard-value resistor lower than the
calculated value. A lower value for total resistance dissi-
pates more power but provides slightly better accuracy.
MOSFET Selection
Output p-Channel MOSFET (P2)
Select the external output MOSFET according to the
application current level. The MOSFET’s on-resistance
(RDS(ON)) should be chosen low enough to have a
minimum voltage drop at full load to limit the MOSFET
power dissipation. Determine the device power rating to
accommodate an overvoltage fault when operating the
MAX16915 in overvoltage-limiting mode. During normal
operation for either IC, the external MOSFET dissipates
little power. The power dissipated in the MOSFET during
normal operation is:
PNORM = ILOAD2 x RDS(ON)
where PNORM is the power dissipated in the MOSFET
in normal operation, ILOAD is the output load current,
and RDS(ON) is the drain-to-source resistance of the
MOSFET. Worst-case power dissipation in the output
MOSFET occurs during a prolonged overvoltage event
when operating the MAX16915 in voltage-limiting mode.
The power dissipated across the MOSFET is as follows:
POVLO = VDS x ILOAD
where POVLO is the power dissipated in the MOSFET in
overvoltage-limiting operation, VDS is the voltage across
the MOSFET’s drain and source, and ILOAD is the load
current.
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 9
© 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Reverse-Polarity Protection MOSFET (P1)
Most battery-powered applications must include reverse-
voltage protection. Many times this is implemented with
a diode in series with the battery. The disadvantage in
using a diode is the forward-voltage drop of the diode,
which reduces the operating voltage available to down-
stream circuits (VLOAD = VBATTERY - VDIODE).
The MAX16914/MAX16915 include high-voltage GATE1
drive circuitry allowing users to replace the high-voltage
drop series diode with a low-voltage-drop MOSFET
device (as shown in the Typical Operating Circuit). The
forward-voltage drop is reduced to ILOAD x RDS(ON) of
P1. With a suitably chosen MOSFET, the voltage drop
can be reduced to millivolts.
In normal operating mode, internal GATE1 output cir-
cuitry enhances P1. The constant enhancement ensures
P1 operates in a low RDS(ON) mode, but the gate-source
junction is not overstressed during high battery-voltage
applications or transients (many MOSFET devices specify
a Q20V VGS absolute maximum). As VCC drops below
10V, GATE1 is limited to GND, reducing P1 VGS to VCC.
In normal operation, the P1 power dissipation is very low:
P1 = ILOAD2 x RDS(ON)
During reverse-battery conditions, GATE1 is limited to
GND and the P1 gate-source junction is reverse biased.
P1 is turned off and neither the MAX16914/MAX16915
nor the load circuitry is exposed to the reverse-battery
voltage. Care should be taken to place P1 (and its inter-
nal drain-to-source diode) in the correct orientation for
proper reverse-battery operation.
Thermal Shutdown
The MAX16914/MAX16915 thermal-shutdown feature
turns off both MOSFETs if the IC junction temperature
exceeds the maximum allowable thermal dissipation.
When the junction temperature exceeds TJ = +170NC,
the thermal sensor signals the shutdown logic, turning off
both GATE1 and GATE2 outputs and allowing the device
to cool. The thermal sensor turns GATE1 and GATE2 on
again after the IC’s junction temperature cools by 20NC.
For continuous operation, do not exceed the absolute
maximum junction-temperature rating of TJ = +150NC.
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
10 FMAX U10+2 21-0061
