LT1910 Linear Technology, LT1910 Datasheet - Page 10

• Manufacturer Part Number: LT1910
• Description: Protected High Side MOSFET Driver
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
LT1910
Low Voltage/Wide Supply Range Operation
When the supply is less than 12V, the LT1910’s charge
pump does not produce sufficient gate voltage to fully
enhance the standard N-channel MOSFET. For these appli-
cations, a logic-level MOSFET can be used to extend the
operating supply down to 8V. If the MOSFET has a maxi-
mum V
also operate up to a supply voltage of 60V (absolute
maximum rating of the V
Protecting Against Supply Transients
The LT1910 is 100% tested and guaranteed to be safe
from damage with 60V applied between the V
pins. However, when this voltage is exceeded, even for a
few microseconds, the result can be catastrophic. For this
reason it is imperative that the LT1910 is not exposed to
supply transients above 60V. A transient suppressor, such
as Diodes Inc.’s SMAJ48A, should be added between the
V
For proper current sense operation, the V
to be connected to the positive side of the drain sense
resistor (see Drain Sense Configuration). Therefore, the
supply should be adequately decoupled at the node where
the V
microfarads may be required when operating with a high
current switch.
When the operating voltage approaches the 60V absolute
maximum rating of the LT1910, local supply decoupling
10
+
and GND pins for such applications.
+
pin and drain sense resistor meet. Several hundred
GS
rating of 15V or greater, then the LT1910 can
U
FAULT OUTPUT
+
U
INPUT
pin).
5V
R1
5.1k
W
Figure 8b. Low Side Driver for Source Current Sensing
3
4
2
C
1 F
FAULT
IN
TIMER
T
+
pin is required
LT1910
GND
SENSE
1
+
GATE
U
and GND
V
10 F
+
50V
C1
8V TO 24V
8
6
5
+
2N2222
between the V
RC snubber with a transient suppressor are an absolute
necessity. Note however that resistance should not be
added in series with the V
error in the current sense threshold.
Low Side Driving
Although the LT1910 is primarily targeted at high side
(grounded load) switch applications, it can also be used
for low side (supply connected load) switch applications.
Figures 8a and 8b illustrate the LT1910 driving low side
power MOSFETs. Because the LT1910 charge pump tries
to pump the gate of the N-channel MOSFET above the
supply, a clamp zener is required to prevent the V
(absolute maximum) of the MOSFET from being exceeded.
51
51
FAULT OUTPUT
Figure 8a. Low Side Driver with Load Current Sensing
12V TO 48V
LT1006
1N4744
INPUT
15V
+
5V
0V
–
+
and GND pins is highly recommended. An
R1
5.1k
1910 F08b
LOAD
2
3
4
HV
HV
C
1 F
FAULT
IN
TIMER
R
0.02
Q1
IRF630
T
S
LT1910
+
GND
SENSE
pin because it will cause an
1
GATE
V
+
8
6
5
+
C1
100 F
100V
15V
1N4744
LOAD
4A
1910 F08a
R
0.01
(PTC)
Q1
IRFZ44
sn1910 1910fs
S
GS