Datasheet

LTC2960
14
2960f
TYPICAL APPLICATIONS
The LTC2960-2 in Figure 10 is yet another way to prevent
excessive discharge of a battery. The high voltage OUT
output is used to drive the gate of a PMOS switch to in-
terrupt the path to V
OUT
in the event of an undervoltage
condition. When the battery stack voltage is above the
IN
–
rising threshold of 5.972V, the PMOS switch is turned
on. The LTC2960-2 also supervises V
OUT
to provide a low
battery signal as an early warning of impending shutdown.
A 10k resistor is included in series with the V
CC
pin to limit
current in the event of a reverse battery condition. In all
three examples, the load drops to <2.5μA typically and
excessive battery drain is prevented.
Automotive Supervisor (LTC2960 H-Grade)
The circuit in Figure 11 uses the LTC2960-3 (H-grade) as a
low voltage supervisor capable of operating in temperatures
up to 125°C in automotive environments. The LT4356 surge
stopper limits V
IN
to 27V under the alternator load dump
condition. The LT3991 buck regulator in conjunction with
the LTC2960 draw <10μA quiescent current for no load,
which limits the drain on the vehicle battery even after
long periods of inactivity.
Window Comparator for High Voltage Input
The LTC2960-4 can be configured as a window compara-
tor to monitor high voltage supplies or battery stacks as
shown in Figure 12. A fault signal is generated if V
IN
is out
of regulation. The OUT output of the LTC2960-4 is fed back
into the MR input to drive the RST output. A micropower
LDO provides bias to the active pull-up DV
CC
supply for
low static current draw in the outputs.
Micropower Power Supply Sequencer and Supervisor
Figure 13 illustrates multiple uses for the LTC2960 in a
power supply system. U1 is a power supply sequencer
whose IN
+
input monitors V
IN
and enables the 5V switch-
ing regulator. The ADJ input monitors the output of the
5V switching regulator and enables the 1.8V LDO after a
16ms Reset Timeout Period. U2 is a supervisor monitor-
ing the 5V and 1.8V outputs. The OUT output by virtue
of the MR pin, keeps the RST output low until the 1.8V
supply is ready.
LT3009-5
V
IN
GND
OUT
SHDN
LTC2960-4
V
CC
GND
MR
IN
–
ADJ
DV
CC
RST
OUT
R3A
7.32M*
R3B
118k*
R4
10k
R2
68k*
V
IN
16.4V
V
OUT
5V
20mA MAX
C1
0.1μF
50V
R1
182k*
FAULT
2960 F12
C2
1μF
16V
UPPER THRESHOLD = 16.897V
LOWER THRESHOLD = 12.3V
*VISHAY-DALE CRCW SERIES 0603 1%
Figure 12. Window Comparator for High Voltage Input