LTC4210-2IS6#PBF Linear Technology, LTC4210-2IS6#PBF Datasheet - Page 13

• Manufacturer Part Number: LTC4210-2IS6#PBF
• Manufacturer: Linear Technology

Specifications of LTC4210-2IS6#PBF

• Linear Misc Type: Positive Low Voltage
• Family Name: LTC4210-2
• Package Type: TSOT-23
• Operating Supply Voltage (min): 2.7V
• Operating Supply Voltage (max): 16.5V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Height (mm): 0.9mm
• Product Length (mm): 2.9mm
• Mounting: Surface Mount
• Pin Count: 6
• Lead Free Status / RoHS Status: Compliant

APPLICATIO S I FOR ATIO
Circuit Breaker Timer Operation
When a current limit fault is encountered at time point A in
Figure 5, the circuit breaker timing is activated with a 60 A
pull-up. The circuit breaker trips at time point B if the fault
is still present and the TIMER pin voltage reaches the
COMP2 threshold and the LTC4210 shuts down. For a
continuous fault, the circuit breaker delay is:
Intermittent overloads may exceed the current limit as in
Figure 6, but if the duration is sufficiently short, the TIMER
pin may not reach the COMP2 threshold and the LTC4210
will not shut down. To handle this situation, the TIMER
discharges with 2 A whenever (V
below the 50mV limit and the TIMER voltage is between
the COMP1 and COMP2 thresholds. When the TIMER
voltage falls below the COMP1 threshold, the TIMER pin is
discharged with an equivalent 7k resistor (normal mode,
100 A source) when (V
50mV limit. If the TIMER pin does not drop below the
COMP1 threshold, any intermittent overload with an ag-
gregate duty cycle of more than 3.8% will eventually trip
the circuit breaker. Figure 7 shows the circuit breaker
response time in seconds normalized to 1 F. The asym-
metric charging and discharging of TIMER is a fair gauge
of MOSFET heating.
When the circuit breaker trips, the GATE pin is pulled low.
The TIMER enters latchoff mode with a 5 A pull-up for the
LTC4210-2 (latched-off version), while an autoretry “cool-
off” cycle begins with a 2 A pull-down for the LTC4210-1
(autoretry version). An autoretry cool-off delay of the
LTC4210-1 between COMP2 and COMP1 thresholds takes:
t
t
C
CBDELAY
COOLOFF
TIMER
t
( /
s
1 1
1 3
.
.
F
)
V
V
U
•
•
C
C
60
60
TIMER
2
TIMER
CC
1 3
U
A
.
– SENSE) voltage is below the
A D
A
V
•
•
1
–
CC
F
2
W
– SENSE) voltage is
A
U
(13)
(14)
(15)
COMP2
V
V
I
TIMER
LOAD
GATE
V
TIMER
Figure 6. Mulitple Intermittent Overcurrent Conditon
60 A
100 A
NORMAL
0.01
A1
MODE
Figure 7. Circuit Breaker Timer Response
for Intermittent Overload
0.1
Figure 5. A Continuous Fault Timing
FAULT
1
10 A
CB
0
LTC4210-1/LTC4210-2
B1
10
A
2 A
60 A
COMP2
OVERLOAD DUTY CYCLE, D (%)
20
FAULT
A2
MODE
COMP1
FAULT
30
10 A
CB
C
TIMER
t
40
B2
60 A
B
60 A
2 A
4210 F05
(s/ F) =
50
CIRCUIT BREAKER
TRIPS
A3
FAULT
CB
60
LATCHED OFF (5 A PULL-UP)
OR RETRY (2 A PULL-DOWN)
B3
60 A • D – 2 A
70
OR RETRY (2 A PULL-DOWN)
1.3V • 1 F
LATCHED OFF (5 A PULL-UP)
COMP1
~50mV/R
CIRCUIT BREAKER
TRIPS
80
4210 F06
90
4210 F07
SENSE
100
13
421012f