LTC1696HS6 View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
LTC1696HS6 Datasheet PDF : 14 Pages
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LTC1696
APPLICATIONS INFORMATION
Glitch Filter Timer
The LTC1696 has a programmable glitch filter to prevent
the output from entering its active high latched condition
if transients occur on the FB1 or FB2 pins. The filter time
delay is programmed externally by an external capacitor
C1 connected to the TIMER/RESET pin.
The
time
delay
is
given
by:
tD
=
C1• VINT
ICHG
where VINT is the internal reference voltage of 1.185V and
ICHG is the internal current source charging the external
capacitor C1. The current source ICHG charging the external
timer capacitor is 10µA for small feedback transients and
increases to 12µA for large feedback transients (greater
than 100mV) from one feedback input. The charging
current increases to 18µA for large feedback transients
from both feedback inputs.
SCR Crowbar
The LTC1696 can deliver continuous output current typi-
cally 80mA at high supply voltage to trigger an external
SCR crowbar in the event of an overvoltage condition as
shown in the typical application on the front page of the
data sheet. The output current decreases when the supply
voltage reduces. It delivers 25mA at a supply voltage of
5V. At a low supply voltage of 3.3V, the output current
reduces to 10mA and an external NPN emitter follower
is needed to boost the current in order to drive the SCR
crowbar as shown in Figure 2. The power dissipation
due to the high output current at high supply voltage can
potentially exceed the thermal limit of the package. This is
avoided by resetting the device rapidly when the external
SCR crowbar has been triggered, so that the device is not
kept in the active high state for too long.
VCC
3.3V
Q1
2N3904
R5
470Ω
5%
R6
22Ω
5%
POWER
SUPPLY
VOUT2
2.5V
VOUT1
1.8 V
R2
54.9k
1%
R1
44.2k
1%
1
FB1
TIMER/ 6
RESET
C1
1nF
LTC1696
2
GND
5
FB2
SCR
2N6507
3
VCC
C2
0.1µF
4
OUT
1696 F02
R4
93.1k
1%
Q2
2N7002
R3
44.2k
1%
RESET
Figure 2. External SCR with NPN Emitter Follower with Low Voltage Supplies
10
For more information www.linear.com/LTC1696
1696fb
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