LT1161 LINER [Linear Technology], LT1161 Datasheet - Page 9

• Manufacturer Part Number: LT1161
• Description: Quad Protected High-Side MOSFET Driver
• Manufacturer: LINER [Linear Technology]

APPLICATIONS
TYPICAL APPLICATIONS
Current sensing for protecting low-side drivers can be
done in several different ways. In the Figure 9a circuit, the
supply voltage for the load is assumed to be within the
1 F
1 F
Figure 9b. Low-Side Drivers with Two Approaches
for Source Current Sensing
T1
T2
(MAY BE PARALLELED)
V
+
LT1161
V
DS2
DS1
+
G1
G2
INPUTS
U
2N2222
2N2222
51
Using an Extra Channel to Do Common Current Limit for Multiple/Paralleled Switches
INFORMATION
1N4148
U
51
51
1 F
8V TO 24V
LT1013
+
1/2
U
100k
1N4744
+
–
W
+
15V
10 F
1N4744
10
LOAD
15V
1
2
3
4
5
6
7
8
9
HV
IRF630
R
0.2
GND
T1
IN1
T2
IN2
T3
IN3
T4
IN4
GND
U
HV
S1
LOAD
LT1161
HV
1161 F09b
IRF630
R
0.02
S2
DS1
DS2
DS3
DS4
V
G1
G2
G3
G4
V
+
+
20
19
18
17
16
15
14
13
12
11
supply operating range of the LT1161. This allows the load
to be returned to supply through current-sense resistor
R
circuitry.
If the load cannot be returned to supply through R
load supply voltage is higher than the LT1161 supply, the
current sense must be moved to the source of the low-side
MOSFET. Figure 9b shows two approaches to source
sensing. On channel 1, current limit occurs when the
voltage across sense resistor R
NPN transistor, causing the LT1161 drain sense pin to be
pulled down.
The channel 2 circuit of Figure 9b uses an operational
amplifier (must common mode to ground) to level shift the
voltage across R
proach allows the use of a much smaller sense resistor
which could be made from PC trace material. In both
cases, the LT1161 restart timers function the same as in
high-side switch applications.
S
, providing normal operation of the LT1161 protection
15k
IRFZ44
IRFZ44
IRFZ44
S2
24V
R
up to the drain sense pin. This ap-
S
+
S1
10 F
50V
OUTPUTS
(MAY BE PARALLELED)
thresholds the V
1161 TA05
LT1161
S
BE
, or the
of the
9