LTC4253CGN Linear Technology, LTC4253CGN Datasheet - Page 15

• Manufacturer Part Number: LTC4253CGN
• Description: IC HOT SWAP CONTRLR -48V 16-SSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4253CGN

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: 11.2 V ~ 14.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

applicaTions inForMaTion
pulse. To protect V
plitude spikes, clamp V
Star connect V
sense resistor Kelvin terminal as illustrated in Figure 3,
keeping trace lengths between V
short as possible.
INTERNAL UNDERVOLTAGE LOCKOUT (UVLO)
A hysteretic comparator, UVLO, monitors V
age. The thresholds are defined by V
V
below (V
The UVLO function at V
UV and OV pins. These are completely separate functions.
UV/OV COMPARATORS (LTC4253)
A UV hysteretic comparator detects undervoltage condi-
tions at the UV pin, with the following thresholds:
LKH
UV low-to-high (V
UV high-to-low (V
. When V
– 48V RTN
(LONG PIN)
– 48V RTN
(SHORT PIN)
– 48V
(LONG PIN)
LKO
30.1k
392k
1%
1%
R2
R1
– V
IN
EE
47k
LKH
R9
rises above V
and all V
), it is disabled and GATE is pulled low.
IN
UVHI
UVLO
against damage from higher am-
IN
C1
10nF
IN
should not be confused with the
) = 3.225V
0.1µF
) = 2.925V
C
RESET
C
to V
PUSH
EE
SS
SQ
33nF
-referred components to the
20k(1/4W)/2
EE
C
0.68µF
LKO
UV
OV
RESET
SS
SQTIMER
TIMER
T
with a 13V Zener diode.
IN
, the chip is enabled;
R
10k
LTC4253A
, C
LKO
IN
V
V
Figure 3. –48V/2.5A Application for the LTC4253A
IN
EE
IN
PWRGD1
PWRGD2
PWRGD3
and its hysteresis
, D
SENSE
DRAIN
GATE
IN
EN3
EN2
D
DDZ13B*
IN
IN
for undervolt-
††
1µF
C
IN
and V
R3 22k
EE
(Refer to Block Diagram)
R
R
10
D
C
C
10nF
1M
C
as
Q2
FZT857
R4
2.2k
Q1
IRF530S
R
0.02
†
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 resistive
divider is used to scale the supply voltage. Using 402k and
32.4k gives a typical operating range of 43.2V to 82.5V.
The undervoltage shutdown and overvoltage recovery
thresholds are then 39.2V and 78.4V. 1% divider resistors
are recommended to preserve threshold accuracy.
The resistive divider values shown set a standing current
of slightly more than 100µA and define an impedance at
UV/OV of 30kΩ. In most applications, 30kΩ impedance
coupled with 300mV UV hysteresis make the LTC4253
insensitive to noise. If more noise immunity is desired,
add a 1nF to 10nF filter capacitor from UV/OV to V
S
OV low-to-high (V
OV high-to-low (V
EN2
R5
2.2k
V
V
IN1
†
†
IN1
R6
2.2k
LTC4253/LTC4253A
100µF
R7
†
C
L
OVHI
OVLO
+
POWER
MODULE 1
OUTPUT
) = 6.150V
) = 5.850V
EN3
EN
MODULE 1
POWER
*DIODES, INC.
†
††
MOC207
RECOMMENDED FOR HARSH ENVIRONMENTS.
V
†
IN1
MODULE 2
EN
MODULE 2
OUTPUT
POWER
POWER
R8
15
EN
MODULE 3
425353afd
EE
POWER
.
4253 F03