LT1640LIS8#TR Linear Technology, LT1640LIS8#TR Datasheet - Page 11

• Manufacturer Part Number: LT1640LIS8#TR
• Description: IC CTRLR HOTSWAP NEG VOLT 8SOIC
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LT1640LIS8#TR

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: -10 V ~ -80 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Family Name: LT1640L
• Package Type: SOIC N
• Operating Supply Voltage (min): -10V
• Operating Supply Voltage (max): -80V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 3.99mm
• Product Height (mm): 1.5mm
• Product Length (mm): 5mm
• Mounting: Surface Mount
• Pin Count: 8
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS
Undervoltage and Overvoltage Detection
The UV (Pin 3) and OV (Pin 2) pins can be used to detect
undervoltage and overvoltage conditions at the power
supply input. The UV and OV pins are internally connected
to analog comparators with 20mV of hysteresis. When the
UV pin falls below its threshold or the OV pin rises above
its threshold, the GATE pin is immediately pulled low. The
GATE pin will be held low until UV is high and OV is low.
The undervoltage and overvoltage trip voltages can be
programmed using a three resistor divider as shown in
Figure 10a. With R4 = 562k, R5 = 9.09k and R6 = 10K, the
U
INFORMATION
U
UV
UV
OV
Figure 10b. Programmable Hysteresis for Undervoltage Detection
* DIODES INC. SMAT70A
– 48V
GND
= 37.6V
= 43V
= 71V
W
Figure 10a. Undervoltage and Overvoltage Sensing
*
V
V
UV
OV
= 1.223
= 1.223
8.87k
506k
1%
1%
R4
R5
GND
R4 + R5+ R6
R4 + R5+ R6
16.9k
U
562k
R5 + R6
1%
1%
R1
R2
(SHORT PIN)
– 48V
R6
GND
GND
1.62M
1%
R3
R4
R5
R6
(SHORT PIN)
2
3
OV
UV
3
V
V
undervoltage threshold is set to 37V and the overvoltage
threshold is set to 71V. The resistor divider will also gain
up the 20mV hysteresis at the UV pin and OV pin to 0.6V
and 1.2V at the input respectively.
More hysteresis can be added to the UV threshold by
connecting resistor R3 between the UV pin and the GATE
pin as shown in Figure 10b.
3
2
DD
EE
8
4
1
UV
OV
0.02
5%
R1
LT1640H
LT1640L /LT1640H
LT1640L
V
V
SENSE
2
DD
EE
4
8
4
5
1640 F10a
C1
150nF
25V
IRF530
GATE
Q1
6
R6
10
5%
1640 F10b
LT1640L/LT1640H
11
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