TA7291J 데이터 시트보기 (PDF) - Toshiba

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TA7291J

BRIDGE DRIVER

Toshiba 

Notes

TA7291AP/AS(J)/AF

· Power On/Off

At power on, VCC must be applied simultaneously or before VS. At power off, VCC must be removed

simultaneously or after VS.

· Input Circuit

VCC standby

A logic high on the VIN pin activates the input

circuit as shown in the figure.

When a voltage greater than or equal to VIN (high)

is applied to the pin, the circuit is active. When a VIN

voltage less than or equal to VIN (low) is applied to

VIN

1 kW

5/9/7

the pin or the pin is grounded, the circuit is

inactive.

When the pin is high, the input current IIN flows

or

6/1/9

into the input circuit. So, be careful about the

5 kW

output impedance of the first stage.

The input hysteresis is 0.7 V (typ.). At power on

(VCC), set both input pins IN1 and IN2 to low.

1/5/1

TA7291AP/TA7291AS (J)/TA7291AF

· Output Circuit

Output high voltage

· Operation based on the Vref voltage

The Vref voltage is increased by twice the value

of VBE (small signal) in the Vref circuit. Then,

the voltage is applied to the base A of Q2 (power

transistor 2). As a result, the voltage which is

reduced by the value of VBE (Q2) appears on the

VOUT pin.

VOUT = Vref + 2VBE－VBE (Q2) ~- Vref + 0.7 V

· Vref pin

The Vref pin must not be left open when unused.

In this case, connect it via a protection resistor

(3 kW or more) to the VS pin. Otherwise, it

might cause oscillation.

Vref must be £ VS.

Q1

Q2

A

Vref

circuit

8/6/15

or 10/3/13

2/7/4 VOUT

4/8/5 Vref

1/5/1

TA7291AP/TA7291AS (J)/TA7291AF

Protection Features

Overcurrent Protection Circuit

The overcurrent protection circuit detects a current flowing through the upper power transistor. If the

current exceeds a predetermined value (about 2.5 A), the circuit turns all the power transistors off.

However, it does not always prevent overcurrent. If an output pin is shorted or grounded, the IC might be

destroyed before operation of the overcurrent protection circuit. So, be sure to connect a resistor or fuse to

the power supply (VS) line. (See “Application Circuit.”)

Thermal Shutdown Circuit

If the chip temperature exceeds a predetermined limit (about 170°C), the thermal shutdown circuit turns

all the power transistors off.

9

2003-02-14

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