LT6109-1/LT6109-2
24
610912fa
TYPICAL APPLICATIONSTYPICAL APPLICATIONS
Power-On Reset or Disconnect Using a TimerBlox
®
Circuit
–
+
–
+
V
–
V
+
V
+
V
–
–
+
V
–
5
INC1
610912 TA06
V
+
400mV
REFERENCE
V
+
R
IN
100Ω
R
SENSE
I
LOAD
R5
10k
INC2
OUTA
6
7
8
9
SENSEHI
LT6109-1
SENSELO
OUTC2
OUTC1
EN/RST
10
1
3
4
2
R1
8.06k
R2
1.5k
R3
499Ω
R4
10k
R7
1M
R6
487k
R8
30k
TRIG
C1
0.1µF
Q1
2N2222
OUT
GND V
+
SET DIV
LTC6993-3
5V
CREATES A DELAYED
10µs RESET PULSE
ON START-UP
OPTIONAL:
DISCHARGES C1
WHEN SUPPLY
IS DISCONNECTED
The LTC6993-1 provides a 10µS reset pulse to the LT6109-1.
The reset pulse is delayed by R7 and C1 whose time constant
must be greater than 10ms and longer than the supply
turn-on time. Optional components R8 and Q1 discharge
capacitor C1 when the supply and/or ground are discon-
nected. This ensures that when the power supply and/or
ground are restored, capacitor C1 can fully recharge and
trigger the LTC6993-3 to produce another comparator reset
pulse. These optional components are particularly useful
if the power and/or ground connections are intermittent,
as can occur when PCB are plugged into a connector.