MAX16914 [MAXIM]
Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs; 理想二极管,电池反接及过压保护开关/限幅控制器,外置MOSFET型号: | MAX16914 |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs |
文件: | 总9页 (文件大小:1070K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
Ordering Information
PART
TEMP RANGE
-40NC to +125NC
-40NC to +125NC
PIN-PACKAGE
10 FMAX
MAX16914AUB/V+
MAX16915AUB/V+
10 FMAX
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified device.
Typical Operating Circuit
P1
P2
V
V
BATT
OUT
V
GATE2
CC
MAX16914
MAX16915
TOP VIEW
GATE1
SENSE OUT
+
V
1
2
3
4
5
10 GATE2
OV
CC
SENSE IN
OV
GATE1
SENSE IN
SHDN
9
8
7
6
SENSE OUT
TERM
MAX16914
MAX16915
TERM
SET
ON
OFF
SHDN
R1
R2
SET
OV
GND
GND
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
ABSOLUTE MAXIMUM RATINGS
V
V
V
, SENSE OUT, TERM, SHDN, OV to GND for
GATE1, GATE2 to GND ........................... -0.3V to (V
SET to GND.............................................................-0.3V to +8V
+ 0.3V)
CC
CC
P 400ms.............................................................-0.3V to +44V
, SENSE OUT, TERM, SHDN, OV to GND
CC
Continuous Power Dissipation (T = +70NC)
A
for P 90s.............................................................-0.3V to +28V
10-Pin FMAX (derate 8.8mW/NC above T = +70NC)
A
, SENSE OUT, TERM, SHDN, OV to GND .....-0.3V to +20V
CC
(Note 1).......................................................................707mW
Operating Temperature Range........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
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 V ..........................................-16V to +0.3V
CC
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.
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
(VCC = 14V, CGATE1 = 32nF, CGATE2 = 32nF, SHDN = high, TA = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
19
UNITS
Operating Voltage Range
V
CC
(Note 3)
4.5
V
T
T
3)
= +25NC
6.0
6.1
12
A
= +85NC (Note
Shutdown Supply Current
SHDN = low,
A
12
(I
+ I
VCC
+ I
+
+
I
V = 0V,
SENSE OUT
FA
FA
SENSE IN
SENSE OUT
)
OV
SHDN
I
+ I
V = 0V
TERM
SHDN
T
= +125NC
A
6.2
29
30
12
53
55
(Note 3)
T
T
= +25NC
A
= +85NC (Note
Quiescent Supply Current
A
3)
(I
+ I
+ I
VCC
+ I
I
Q
SHDN = high
SENSE IN
SENSE OUT
)
OV
I
SHDN
T
= +125NC
A
31
4.06
8
57
(Note 3)
V
V
Undervoltage Lockout
Undervoltage-Lockout
V
V
V
V
rising, V
= 1V , SHDN = high
SET
4.35
V
%
V
CC
UVLO
CC
CC
Hysteresis
SET Threshold Voltage
V
V
rising
-3%
+1.20
4
+3%
SETTH
SET
SET
SHDN
SET Threshold Voltage
Hysteresis
%
SETHY
SET Input Current
I
= 1V
0.02
0.2
0.4
FA
V
SET
SHDN Low Threshold
SHDN High Threshold
SHDN Pulldown Current
V
SHDNL
SHDNH
V
1.4
V
I
V
V
V
= 14V, internally pulled to GND
= 14V
0.5
7.5
1.0
8.5
14
FA
SHDN
V
CC
to GATE Output Low
V
V
6.25
V
V
GVCC1
GVCC2
CC
CC
Voltage
V
CC
to GATE Clamp Voltage
= 42V
2
______________________________________________________________________________________
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
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)
PARAMETER
TERM On-Resistance
TERM Output Current
SYMBOL
CONDITIONS
SHDN = high
SHDN = low, V
MIN
TYP
MAX
500
1.0
UNITS
I
R
150
TERM
TERM
I
= 0V
FA
TERM
Back-Charge Voltage Fault
Threshold
V
V
V
= 14V (Note 4)
= 14V
18
25
50
32
mV
BCTH
BCHY
SENSE OUT
Back-Charge Voltage Threshold
Hysteresis
V
mV
SENSE OUT
V
V
= 9.5V, V
= 9V,
CC
SENSE IN
Back-Charge Turn-Off Time
(GATE1)
t
stepped from 4.9V to 9.5V
6
10
30
Fs
BC
SENSE OUT
(Note 5)
V
V
= 9.5V, V
= 9V,
CC
SENSE IN
Back-Charge Recovery Time
(GATE1)
t
stepped from 9.5V to 4.9V
18
Fs
BCREC
SENSE OUT
(Note 6)
V
= 9.5V, V
rising from 1V to
CC
SET
SET
GATE2 Turn-Off Time
3
Fs
Fs
Fs
ms
1.5V (Note 7)
V
CC
= 9.5V, V
falling from 1.5V to
GATE2 Turn-On Time
Startup Response Time
20
1V (Note 8)
V
V
= 9.5V, from V
rising to
CC
SHDN
t
t
100
0.150
START1
(V
SHDN
Rising)
falling (Note 9)
GATE_
Startup Response Time
(V Rising)
V
CC
rising from 2V to 4.5V, SHDN =
START2
high (Note 10)
CC
V
and V
falling from 4.25V
CC
SENSE IN
Reverse-Battery Voltage Turn-Off
Time/UVLO Turn-Off Time
t
to 3.25V, V
(Note 11)
= 4.25V
30
Fs
REVERSE
SENSE OUT
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
OV Output Low Voltage
+170
20
NC
NC
V
V
I
= 600FA
SINK
0.4
1.0
5
OVBL
OV Open-Drain Leakage Current
SENSE IN Input Current
I
V
V
V
V
= 1.0V
FA
FA
FA
OVB
SENSE IN
SET
I
= 0/14V
= 0/14V
1
2
SHDN
SHDN
SENSE OUT Input Current
I
5
SENSE OUT
SET to OV Output Low
Propagation Delay
= 9.5V, V
rising from 1V to
CC
SET
t
3
Fs
OVBPD
1.5V to V
falling
OV
Note 2: All parameters are production tested at T = +25NC. Limits over the operating temperature range are guaranteed by
A
design and characterization.
Note 3: Guaranteed by design and characterization.
Note 4: The back-charge voltage, V , is defined as the voltage at SENSE OUT minus the voltage at SENSE IN.
BC
Note 5: Defined as the time from when V
Note 6: Defined as the time from when V
Note 7: Defined as the time from when V
Note 8: Defined as the time from when V
Note 9: The external pFETs can turn on t
Note 10:Defined as the time from when V
fall below 1V.
exceeds V
falls below V
(25mV typ) to when V
exceeds V
CC
- 3.5V.
- 3.5V.
BC
BCTH
GATE1
- 50mV to when V falls below V
GATE1 CC
BC
BCTH
exceeds V
(1.20V typ) to when V
exceeds V - 3.5V.
CC
SET
SET
START
SETTH
GATE2
falls below V
- 5% (1.14V typ) to when V
falls below V
- 3.5V.
SETTH
GATE2
CC
after the IC is powered up and all input conditions are valid.
exceeds the undervoltage-lockout threshold (4.3V max) to when V
and V
GATE2
CC
GATE1
Note 11:Defined as the time from when V
falls below V
- 25mV to when V
reaches V
- 1.75V.
CC
SENSE OUT
GATE1
CC
_______________________________________________________________________________________
3
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
Typical Operating Characteristics
(V
CC
= 14V, V
= 14V, MAX16914/MAX16915 Evaluation Kit, T = +25NC, unless otherwise noted.)
SHDN A
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
30
40
35
30
25
20
15
10
10
8
MAX16914
25
20
15
10
MAX16914
MAX16915
MAX16915
MAX16914
MAX16915
6
4
TERM = OPEN
SHDN = HIGH
SET = 0V
TERM = OPEN
SHDN = HIGH
2
SHDN = LOW
SET = 0V
SET = 0V, V = 14V
CC
NO LOAD
NO LOAD
0
4.5
7.0
9.5
12.0
14.5
17.0 19.0
-40 -15
10
35
60
85 110 125
4.5
7.0
9.5
12.0
14.5 17.0 19.0
SUPPLY VOLTAGE (V)
TEMPERATURE (NC)
SUPPLY VOLTAGE (V)
SET THRESHOLD
vs. TEMPERATURE
UVLO THRESHOLD
vs. TEMPERATURE
POWER-UP RESPONSE
MAX16914 toc06
1.25
1.20
1.15
1.10
4.3
4.2
4.1
4.0
3.9
3.8
3.7
3.6
3.5
V
CC
10V/div
RISING
RISING
V
OUT
10V/div
V
GATE1
10V/div
FALLING
V
FALLING
GATE2
10V/div
-40 -15 10
35
60
85 110 125
40µs/div
-40 -15 10
35
60
85 110 125
22µF INPUT AND OUTPUT CAPACITOR,
TEMPERATURE (NC)
TEMPERATURE (NC)
R
OUT
= 100I, SHDN = HIGH
OVERVOLTAGE SWITCH-OFF
RESPONSE (MAX16914)
OVERVOLTAGE LIMITER RESPONSE
STARTUP FROM
SHUTDOWN RESPONSE
(MAX16915)
MAX16914 toc09
MAX16914 toc08
MAX16914 toc07
V
V
CC
CC
20V/div
30V
14V
V
30V
14V
SHDN
2V/div
10V/div
V
OUT
10V/div
V
OUT
20V/div
20V
14V
14V
14V
V
OUT
10V/div
V
OV
20V/div
14V
V
GATE1
10V/div
0V
14V
V
OV
0V
20V/div
V
GATE2
14V
V
30V
0V
GATE2
20V/div
V
GATE2
10V/div
20V/div
0V
0V
1.0µs/div
400µs/div
20µs/div
V
= 14V TO 30V
CC
V
= 14V TO 30V
CC
100µF INPUT CAPACITOR, 122µF
TRIP THRESHOLD = 22V
100µF INPUT CAPACITOR, 22µF
TRIP THRESHOLD = 22V
100µF INPUT CAPACITOR, 22µF
OUTPUT CAPACITOR, R
= 100I
OUT
OUTPUT CAPACITOR, R
= 100I
OUT
OUTPUT CAPACITOR, R
= 100I
OUT
C
= 10nF
OV
4
______________________________________________________________________________________
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
Typical Operating Characteristics (continued)
(V
CC
= 14V, V
= 14V, MAX16914/MAX16915 Evaluation Kit, T = +25NC, unless otherwise noted.)
SHDN A
V
- V
GATE-DRIVE VOLTAGE
vs. TEMPERATURE
CC
GATE_
BACK-CHARGE RESPONSE
vs. INPUT VOLTAGE
MAX16914 toc10
15.0
13.5
12.0
10.5
9.0
7.5
6.0
4.5
3.0
1.5
0
6.6
6.5
6.4
6.3
6.2
V
CC
5V/div
GATE1
GATE1
5V
5V
V
OUT
5V/div
GATE2
GATE2
V
GATE1
5V/div
V
= 14V
CC
SET = GND
SHDN = HIGH
SET = GND
SHDN = HIGH
0V
1.0µs/div
4.5 9.0 13.5 18.0 22.5 27.0 31.5 36.0 40.5 44.0
SUPPLY VOLTAGE (V)
-40 -15 10
35
60
85 110 125
2.2µF INPUT CAPACITOR, 400I
INPUT RESISTOR, 22µF OUTPUT CAPACITOR
TEMPERATURE (NC)
Pin Description
PIN
NAME
FUNCTION
1
V
CC
Positive Supply Input Voltage. Bypass V
to GND with a 0.1FF or greater ceramic capacitor.
CC
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.
2
3
GATE1
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.
SENSE IN
Active-Low Shutdown/Wake Input. Drive SHDN high to turn on the voltage detectors. GATE2 is
4
SHDN
shorted to V
when SHDN is low. SHDN is internally pulled to GND through a 0.5FA current sink.
CC
Connect SHDN to V
for always-on operation.
CC
Open-Drain Overvoltage Indicator Output. Connect a pullup resistor from OV to a positive supply
5
6
OV
such as V . OV is pulled low when the voltage at SET exceeds the internal threshold.
CC
GND
Ground
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.
7
SET
Voltage-Divider Termination Output. TERM is internally connected to SENSE OUT in the MAX16915
8
9
TERM
SENSE OUT
GATE2
and to V
in the MAX16914. TERM is high impedance when SHDN is low, forcing the current to
CC
zero in the resistor-divider connected to TERM.
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.
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 V
10
during an overvolt-
CC
age condition. GATE2 is shorted to V
when SHDN is low.
CC
_______________________________________________________________________________________
5
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
Functional Diagram
V
CC
1.20V
REG
GATE1
OV1
GATE2
SENSE IN
SENSE OUT
SET
TO V FOR
CC
MAX16914
TO SENSE OUT
FOR MAX16915
SHDN
OV
BANDGAP
BIAS
TERM
SWITCH
TERM
GND
OV1
MAX16914
MAX16915
Overvoltage Switch-Off Controller
(MAX16914)
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).
In the MAX16914, the input voltage is monitored (TERM
is internally shorted to V —see the Functional Diagram)
CC
making the device an overvoltage switch-off controller.
As the V
voltage rises, and the programmed overvolt-
age threshold is tripped, the internal fast comparator
turns off the external p-channel MOSFET (P2), pulling
CC
GATE2 to V
to disconnect the power source from
CC
the load. When the monitored voltage goes below the
adjusted overvoltage threshold, the MAX16914 enhanc-
es GATE2, reconnecting the load to the power source.
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.
6
______________________________________________________________________________________
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
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.
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.
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
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.
comparator pulls GATE2 to V
turning off P2. When
CC
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.
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 (V
-
SENSE OUT
V ) > 25mV (see Figure 1) to prevent discharg-
SENSE IN
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.
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).
t
= 10µs (max)
BC
V
V
- V
= 50mV
OUT
BATT
50% (25mV)
V
- V
BATT
= 0V
OUT
= 9V
BATT
50%
I
OUT
Figure 1. Back-Charge Turn-Off Time
_______________________________________________________________________________________
7
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
For example:
Overvoltage Indicator Output (OV)
The MAX16914/MAX16915 include an active-low,
open-drain overvoltage-indicator output (OV). For the
With an overvoltage threshold (V ) set to 20V, R
< 20V/(100 x I
OV
TOTAL
), where I
= 1FA (max).
SET
SET
MAX16914, OV asserts low when V
exceeds the pro-
CC
R
< 200kI
TOTAL
grammed overvoltage threshold. OV deasserts when the
overvoltage condition is over.
Use the following formula to calculate R2:
R2 = (V x R )/V
TH
TOTAL OV
For the MAX16915, OV asserts if V
exceeds the
OUT
programmed overvoltage threshold. OV deasserts when
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
where V is the 1.20V SET rising threshold and V
TH
the desired overvoltage threshold.
is
OV
V
OUT
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.
period (less than t
), the OV pin may not toggle.
OVBPD
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.
To determine R1:
R
= R2 + R1
TOTAL
Then, R1 = 188kI.
Applications Information
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.
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.”
MOSFET Selection
Output p-Channel MOSFET (P2)
Select the external output MOSFET according to the
application current level. The MOSFET’s on-resistance
(R ) should be chosen low enough to have a
DS(ON)
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:
P
= I
2 x R
LOAD DS(ON)
NORM
where P
is the power dissipated in the MOSFET
NORM
in normal operation, I
is the output load current,
LOAD
and R
is the drain-to-source resistance of the
DS(ON)
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
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:
(see the Typical Operating Circuit). V
has a rising
SET
P
OVLO
= V x I
DS LOAD
1.20V threshold with a 4% falling hysteresis. Begin by
selecting the total end-to-end resistance:
where P
is the power dissipated in the MOSFET in
OVLO
overvoltage-limiting operation, V is the voltage across
DS
R
= R1 + R2
TOTAL
the MOSFET’s drain and source, and I
current.
is the load
LOAD
For high accuracy, choose R
rent equivalent to a minimum 100 x I
input bias current at SET.
to yield a total cur-
TOTAL
where I
is the
SET
SET
8
______________________________________________________________________________________
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
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-
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.
stream circuits (V
= V
- V
).
LOAD
BATTERY
DIODE
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
Thermal Shutdown
The MAX16914/MAX16915 thermal-shutdown feature
turns off both MOSFETs if the IC junction temperature
exceeds the maximum allowable thermal dissipation.
forward-voltage drop is reduced to I
x R
of
LOAD
DS(ON)
When the junction temperature exceeds T = +170NC,
J
P1. With a suitably chosen MOSFET, the voltage drop
can be reduced to millivolts.
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
In normal operating mode, internal GATE1 output cir-
cuitry enhances P1. The constant enhancement ensures
P1 operates in a low R
mode, but the gate-source
DS(ON)
maximum junction-temperature rating of T = +150NC.
junction is not overstressed during high battery-voltage
applications or transients (many MOSFET devices specify
J
a Q20V V
absolute maximum). As V
drops below
GS
CC
Chip Information
10V, GATE1 is limited to GND, reducing P1 V
In normal operation, the P1 power dissipation is very low:
to V
.
CC
GS
PROCESS: BiCMOS
P1 = I
2 x R
LOAD
DS(ON)
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
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.
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