LTC4216CMS Просмотр технического описания (PDF) - Linear Technology
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LTC4216CMS Datasheet PDF : 26 Pages
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LTC4216
Block Diagram
VCC
SENSEP
2.12V
+–
UVLO
25mV –+
+–
ECB
SENSEN
GATE
40mV –+
+–
ACL
D1 Z1
CHARGE
PUMP
20µA
M1
VCC VCC
10µA
1µA
TIMER
VCC
2µA
0.2V +
CP4
–
6µs
DELAY
FILTER DELAY
(SEE NOTE 1)
OUT OF UVLO
FAULT LATCH-OFF
M9
VCC
60µA
1.253V
+
CP5
–
NORMAL
FILTER
1.253V
+
CP6
–
2.4µA M10
NOTE 1: FILTER DELAY IS SET BY FILTER PIN CAPACITOR
** ONLY AVAILABLE IN THE DE12 PACKAGE
LOGIC
DEVICE
RESET
FAULT LATCH
RESET
GATE
ON
30µs
DELAY
3µs
DELAY
CP1
+–
CP2
+–
0.4V
0.8V
ON
M4
M3
M2
M5
100µA
CB TRIPS GATE
R1
OR UVLO OFF
GATE ON
GATE OFF
DEVICE RESET, UVLO
OR POWER BAD
FILTER
FUNCTION OF
OVERDRIVE
CP7
CB
TRIPS
CP3
–+
0.6V
FB
SS**
M6
M7
VCC
5µA
RESET
1.253V
D2
FAULT **
M8
GND
4216 BD
Operation
The LTC4216 is a Hot Swap controller residing either on a
removable circuit board or on the backplane. It monitors
the current and protects the load with an external N-channel
MOSFET and a current sensing resistor (see Figures 14
to 18). Both inrush current limiting and short-circuit protec-
tion are provided by the LTC4216. The device is powered
via the bias supply input (VCC) and it has a separate sense
pin, SENSEP, to monitor the load supply (VIN). The load
supply can extend from 0V to 6V, with a minimum bias
supply voltage of 2.3V.
When the ON pin is pulled from low to high, TIMER begins
the first timing cycle by sourcing 2µA into C1 once these
conditions are met: bias supply voltage out of undervolt-
age lockout (> 2.12V); TIMER, SS, FILTER and GATE
pin voltages < 0.2V. When the C1 voltage rises above
the TIMER pin threshold (1.253V), TIMER pulls low and
releases both the SS and GATE pins. C2 starts to ramp
up at the SS pin, controlling the rate of GATE ramp. This
limits the rate of change of the inrush current flowing into
the output load capacitance. RESET pin goes high after
the second timing cycle when the FB pin voltage exceeds
0.6V and its hysteresis.
When the external MOSFET is fully turned on, the output
will ramp to load supply voltage if the inrush into the load
capacitance is low. However, if the inrush current exceeds
the analog current limit of ΔVACL(TH)/RSENSE, the LTC4216
will ramp the output by sourcing the limited current into
the load capacitance.
The LTC4216 provides protection against output short-
circuits or current overload through an internal electronic
circuit breaker with trip threshold of 25mV and an analog
current limit circuit. The circuit breaker response time is
set by C3 at the FILTER pin.
4216fa
8
For more information www.linear.com/LTC4216
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