LT1910 datasheet(10/12 Pages) LINER

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LT1910

sn1910 1910fs

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 VGS rating of 15V or greater, then the LT1910 can

also operate up to a supply voltage of 60V (absolute

maximum rating of the V+ pin).

Protecting Against Supply Transients

The LT1910 is 100% tested and guaranteed to be safe

from damage with 60V applied between the V+ and GND

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+ and GND pins for such applications.

For proper current sense operation, the V+ pin is required

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+ pin and drain sense resistor meet. Several hundred

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

APPLICATIO S I FOR ATIO

between the V+ and GND pins is highly recommended. An

RC snubber with a transient suppressor are an absolute

necessity. Note however that resistance should not be

added in series with the V+ pin because it will cause an

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 VGS

(absolute maximum) of the MOSFET from being exceeded.

Figure 8a. Low Side Driver with Load Current Sensing

Figure 8b. Low Side Driver for Source Current Sensing

FAULT

TIMER

V+

SENSE

GATE

LT1910

5.1k

FAULT OUTPUT

INPUT

GND

IRF630

15V

1N4744

1910 F08b

µF

50V

µF

0.02

Ω

LOAD

Ω

2N2222

8V TO 24V

–

LT1006

Ω

FAULT

V+

SENSE

LT1910

5.1k

12V TO 48V

FAULT OUTPUT

INPUT

GND

IRFZ44

15V

1N4744

1910 F08a

100

µF

100V

µF

0.01

Ω

(PTC)

LOAD

GATE

TIMER

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