LTC1642ACGN Linear Technology, LTC1642ACGN Datasheet - Page 11

• Manufacturer Part Number: LTC1642ACGN
• Description: IC,Electronic Circuit Breaker,CMOS,SSOP,16PIN,PLASTIC
• Manufacturer: Linear Technology

Specifications of LTC1642ACGN

• Linear Misc Type: Positive Low Voltage
• Family Name: LTC1642A
• Package Type: SSOP N
• Operating Supply Voltage (min): 2.97V
• Operating Supply Voltage (max): 16.5V
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Product Depth (mm): 3.99mm
• Product Height (mm): 1.5mm
• Mounting: Surface Mount
• Pin Count: 16
• Lead Free Status / Rohs Status: Not Compliant

APPLICATIO S I FOR ATIO
Automatic Restart After the Circuit Breaker Opens
The LTC1642A will automatically attempt to restart itself
after the circuit breaker opens if the FAULT output is tied
to the ON pin. The circuit is shown in Figure 5. Diode D1
blocks the weak FAULT pull-up current source from unbal-
ancing the R6-R5 divider.
During a continuous current limit such as a load short,
Q1’s duty cycle is equal to the circuit breaker timer period,
divided by the sum of the circuit breaker and system timer
periods:
The duty cycle is 9% for the Figure 5 circuit. Waveforms
during a load short are shown in Figure 6.
Undervoltage Lockout
An internal undervoltage lockout circuit holds the charge
pump off until V
it turns off the charge pump and clears overvoltage and
current limit faults.
For higher lockout thresholds tie the ON pin to a resistor
divider driven from V
circuit keeps the charge pump off until V
(1+R6/R5) • 1.34V, and also turns it off if V
(1+R6/R5) • 1.22V.
Short - Circuit Duty Cycle =
CC
exceeds 2.73V. If V
U
CC
, as shown in Figure 7. This
U
THRESHOLD = 10.7V
ALL RESISTORS ±5% UNLESS NOTED
C
UNDERVOLTAGE
4 10
W
+
CC
C
Figure 7. Setting a Higher Undervoltage Lockout
LOCKOUT
2.5A
12V
4
V
falls below 2.5V,
IN
•
C
CC
1
CC
falls below
U
R6
464k
1%
R5
60.4k
1%
exceeds
4
ON
RST TMR
V
CC
16
LTC1642A
3
0.015Ω
R2
C1
0.33µF
SENSE
GATE
GND
2.5A
15
12V
V
V
V
IN
8
20V/DIV
10V/DIV
BRKTMR
RSTTMR
1V/DIV
1V/DIV
V
V
Figure 6. Automatic Retry Following a Load Short
FDS6630A
14
GATE
OUT
ALL RESISTORS ±5% UNLESS NOTED
Q1
R6
464k
1%
R5
60.4k
1%
0.33µF
R3
100Ω
R4
330Ω
1N4148
C2
0.047µF
C4
Figure 5. Automatic Restart Circuit
D1
R10
30k
+
1642a F07
4
6
2
C
D1
1N4705
18V
LOAD
ON
FAULT
BRK TMR
RST TMR
V
OUT
V
CC
LTC1642A
3
0.015Ω
16
R2
C1
0.33µF
40ms/DIV
SENSE
GATE
GND
15
8
14
FDS6630A
LTC1642A
Q1
R3
100Ω
R4
330Ω
C2
0.047µF
+
1642a F06
1642a F05
C
D2
1N4705
18V
LOAD
V
11
OUT
1642af