Chip information, Package information – Rainbow Electronics MAX16915 User Manual
Page 9
Ideal Diode, Reverse-Battery, and Overvoltage Protection
Switch/Limiter Controllers with External MOSFETs
MAX16914/MAX16915
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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 (V
LOAD
= V
BATTERY
- V
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
forward-voltage drop is reduced to I
LOAD
x R
DS(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 R
DS(ON)
mode, but the gate-source
junction is not overstressed during high battery-voltage
applications or transients (many MOSFET devices specify
a Q20V V
GS
absolute maximum). As V
CC
drops below
10V, GATE1 is limited to GND, reducing P1 V
GS
to V
CC
.
In normal operation, the P1 power dissipation is very low:
P1 = I
LOAD
2
x R
DS(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 T
J
= +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 T
J
= +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