参数资料
型号: LTC4261CUFD-2#PBF
厂商: LINEAR TECHNOLOGY CORP
元件分类: 电源管理
英文描述: Negative Voltage Hot Swap Controllers with ADC and I2C Monitoring; Package: QFN; No of Pins: 24; Temperature Range: 0°C to +70°C
中文描述: 1-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC24
封装: 4 X 5 MM, LEAD FREE, PLASTIC, QFN-24
文件页数: 9/34页
文件大小: 357K
代理商: LTC4261CUFD-2#PBF
LTC4261/LTC4261-2
17
42612fc
EN and ON
Figure 5 shows a logic diagram for EN and ON as they
relate to GATE, ALERT and internal registers A4, A7, B4,
C4 and D3. Also affecting GATE is the status of UV, OV
and several other fault conditions. The EN and ON pins
have 0.8V to 2V logic thresholds relative to VEE with a
maximum input leakage current of ±2A.
Register bit A4 indicates the present state of EN, and B4
is set high whenever EN changes state. Rising and falling
edges at the ON pin set and clear FET-on control bit, D3.
Another path allows a falling edge at EN to latch a high
state at the ON pin (such as when ON is permanently
pulled high) into D3 after a time delay. Both B4 and D3
can be set or cleared directly by I2C, and both are cleared
low whenever INTVCC drops below its UVLO threshold.
The condition of the GATE pin output is controlled by
register bit A7, which is the AND of A4, D3 and the ab-
sence of UV, OV and other faults.
Overcurrent Protection and Overcurrent Fault
The LTC4261/LTC4261-2 feature two levels of protec-
tion from short-circuit and overcurrent conditions. Load
current is monitored by the SENSE pin and resistor
RS. There are two distinct thresholds for the voltage at
SENSE: 50mV for engaging the active current limit loop
and starting a 530s circuit breaker timer and 250mV for
a fast GATE pull-down to limit peak current in the event
of a catastrophic short circuit or an input step.
In an overcurrent condition, when the voltage drop across
RS exceeds 50mV, the current limit loop is engaged and
an internal 530s circuit breaker timer is started. The
current limit loop servos the GATE to maintain a constant
output current of 50mV/RS. When the circuit breaker
timer expires, the FET is turned off by pulling GATE down
with a 110mA current, the capacitors at SS and TMR are
discharged and the power good signals are reset. At this
time, the overcurrent present bit A2 and the overcurrent
fault bit B2 are set, and the circuit breaker timer is reset.
After the FET is turned off, the overcurrent present bit
A2 is cleared. If the overcurrent auto-retry bit D2 has
been set, the FET will turn on again automatically after
a cooling time of 4tD. Otherwise, the FET will remain off
until the overcurrent fault bit B2 is reset. When the over-
current fault bit is reset (see Resetting Faults), the FET
is allowed to turn on again after a delay of 4tD. The 4tD
cooling time associated with the overcurrent fault will not
be interrupted by any other fault condition. See Figure 6
for operation of LTC4261/LTC4261-2 under overcurrent
condition followed by auto-retry.
Figure 5. Logic Block Diagram of EN and ON Pins
APPLICATIONS INFORMATION
R/W
I2C
CLR
Q
S
R
R/W
CLR
INTVCC UVLO
ABSENCE OF UV/OV AND OTHER FAULTS
Q
S
CLR
Q
S
1 tD
TIMER
DELAY
EDGE
DETECTOR
STATE-CHANGE
DETECTOR
EN
ON
B4
C4
ALERT*
GATE ON
ALERT
42612 F05
READ ANY REGISTER
*B4 C4 IS ONE OF SEVEN CONDITIONS
THAT CAN GENERATE AN ALERT OUTPUT.
SEE TABLE 5
I2C ALERT RESPONSE
A4
A7
D3
相关PDF资料
PDF描述
LTC4261CUFD-2#TRPBF Negative Voltage Hot Swap Controllers with ADC and I2C Monitoring; Package: QFN; No of Pins: 24; Temperature Range: 0°C to +70°C
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LTC4261IGN-2 制造商:LINER 制造商全称:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers with ADC and I2C Monitoring