NJM3545

s FUNCTIONAL DESCRIPTION

The circuit NJM3545 is a low side driver capable of driving resistive or inductive loads not exceeding 2 A.

The driver has an error indicating function which generates an Error output signal when a fault condition has

occurred.

The circuits NJM3545 and NJM3548 are complementary drivers with equivalent functions and similar data.

NJM3545 is a sink driver and NJM3548 is a source driver.

Input stage

The output stage is switched on and off according to the status of the input. HIGH level activates the output. If the

input is left open, the circuit will accept it as a LOW level.

Output stage

The output stage contains a power transistor and two clamping diodes. The diodes are used for terminating line

transients from inductive loads. If the driver is inactive and the output is shorted to GND the driver will leak maxi-

mum

8

µA. See figure 18.

Protection circuit

The circuit contains two protection circuits:

•

Overload and Short circuit protection

•

Thermal protection

The overload and short circuit protection will be activated at I

The output will be turned off immediately and latched to a high-impedance state after an overload or short circuit

has been detected.

Figure 6. Output stage

Figure 5. Input stage

5

I

Ref

GND

Input

3

GND

3

1

2

CC

Output

Fault condition

Input

Output

Error

How to resume normal operation

LOW=Error

HIGH=Normal

Normal

0

LOW

1 OFF

1 HIGH

——

1

HIGH

0

ON

1 HIGH

——

V

0

LOW

1 OFF

0

LOW

Remove fault condition.

1

HIGH

0

ON

0

LOW

Remove fault condition.

V

0

LOW

1 OFF

1 HIGH

——

1

HIGH

1 OFF

0

LOW

Turn off and on after fault condition is removed.

Open load

0

LOW

1 OFF

1 HIGH

——

1

HIGH

0

ON

0

LOW

Attach proper load to output or turn off the driver.

Over temperature

0

LOW

1 OFF

1 HIGH

——

T

1

HIGH

1 OFF

0

LOW

Temperature is reduced to approx 120

°C, or turn off the driver.

Figure 7. Error table