LTC4252A-1IMS Linear Technology, LTC4252A-1IMS Datasheet - Page 14

• Manufacturer Part Number: LTC4252A-1IMS
• Description: IC CTRLR HOTSWAP NEG VOLT 10MSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4252A-1IMS

• Applications: General Purpose
• Internal Switch(s): No
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
• Family Name: LTC4252A-1
• Package Type: MSOP
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 3mm
• Product Height (mm): 0.86mm
• Product Length (mm): 3mm
• Mounting: Surface Mount
• Pin Count: 10
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
LTC4252-1/LTC4252-2
LTC4252A-1/LTC4252A-2
SHUNT REGULATOR
A fast responding regulator shunts the LTC4252 V
Power is derived from – 48RTN by an external current
limiting resistor. The shunt regulator clamps V
(V
transients and contributes a short delay at start-up. R
should be chosen to accommodate both V
rent and the drive required for an optocoupler if the
PWRGD function on the 10-pin MS package is used.
Higher current through R
for R
buffer driving the optocoupler as shown in Figure 3.
Multiple 1/4W resistors can replace a single higher power
R
INTERNAL UNDERVOLTAGE LOCKOUT (UVLO)
A hysteretic comparator, UVLO, monitors V
undervoltage. The thresholds are defined by V
hysteresis, V
enabled; below (V
pulled low. The UVLO function at V
confused with the UV/OV pin(s). These are completely
separate functions.
14
IN
Z
). A 1µF decoupling capacitor at V
resistor.
IN
and the LTC4252. An alternative is a separate NPN
LKH
. When V
LKO
U
(SHORT PIN)
– V
–48V
GND
GND
LKH
IN
IN
U
* M0C207
Q2: MMBT5551LT1
results in higher dissipation
rises above V
Figure 3. – 48V/2.5A Application with Different Input Operating Range
4.75k
38.3k
) it is disabled and GATE is
432k
1%
1%
1%
R1
R2
R3
W
C2
10nF
IN
IN
should not be
LKO
IN
filters supply
C
330nF
supply cur-
T
LKO
the chip is
U
IN
10
9
8
3
to 13V
and its
IN
IN
UV
OV
TIMER
SS
C
68nF
SS
pin.
for
IN
LTC4252-1
V
V
EE
IN
5
1
R
10k
1/2W
UV/OV COMPARATORS (LTC4252)
An UV hysteretic comparator detects undervoltage condi-
tions at the UV pin, with the following thresholds:
An OV hysteretic comparator detects overvoltage condi-
tions at the OV pin, with the following thresholds:
The UV and OV trip point ratio is designed to match the
standard telecom operating range of 43V to 82V when
connected together as in the typical application. A divider
(R1, R2) is used to scale the supply voltage. Using R1 =
402k and R2 = 32.4k gives a typical operating range of
43.2V to 82.5V. The undervoltage shutdown and overvolt-
age recovery thresholds are then 39.2V and 74.4V. 1%
divider resistors are recommended to preserve threshold
accuracy.
The R1-R2 divider values shown in the Typical Application
set a standing current of slightly more than 100µA and
define an impedance at UV/OV of 30kΩ. In most applica-
IN
PWRGD
SENSE
DRAIN
GATE
UV low-to-high (V
UV high-to-low (V
OV low-to-high (V
OV high-to-low (V
2
7
6
4
22k
C
1µF
R4
IN
R
D
1M
Q2
R5
2.2k
R
10Ω
C
100µF
C
18nF
UVHI
UVLO
OVHI
OVLO
C
*
C
L
+
) = 3.225V
) = 6.150V
) = 2.925V
) = 5.550V
Q1
IRF530S
4252-1/2 F03
R
0.02Ω
S
EN
LOAD
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