Package Pin Description
PIN SYMBOL
PACKAGE PIN #
FUNCTION
16L PDIP (internally fused leads)
1
DIR1
CMOS compatible input pin controls direction of current
through OUT1
2
C1
RC filter capacitor for OUT1 connected to Ground
CMOS compatible input pin controls output OUT1A and 1B
Ground connection
3
IN1
4,5,12,13
Gnd
6
7
OUT1A
VS1
One half of H-bridge output stage 1
Supply voltage
8
OUT1B
OUT2B
VS2
One half of H-bridge output stage 1
One half of H-bridge output stage 2
Supply voltage
9
10
11
14
15
16
OUT2A
IN2
One half of H-bridge output stage 2
CMOS compatible input pin controls output OUT2A and 2B
RC filter capacitor for OUT2 connected to Ground
C2
DIR2
CMOS compatible input pin controls direction of current
through OUT2
Circuit Description
Output Stage
Protection
Each output stage contains 4 power NPN transistors
arranged in a traditional H bridge configuration. Current
flow through the two outputs (OUTxA, OUTxB) in each
H-bridge is controlled by the logic signal DIRx.
The high side driver transistor in each H-bridge is current
limited as a protection against a short circuit fault condi-
tion. If an over voltage or a thermal runaway fault condi-
tions occurs, all outputs shut down.
PWM input signals from the microprocessor, are filtered
on chip and sent to the output stage. The duty cycle of the
PWM signal is proportional to output voltage. The RC fil-
ter reduces the noise of the PWM input signal by slowing
its slew rate: i.e., the output signal is converted from a
square wave to an exponential sawtooth waveform. An
external capacitor (Cx) controls the slew rate for each H
bridge.
Application Diagram
VBAT
Motor Direction Control
1
DIR2
C2
DIR1
C1
When the voltage on the control pin (INx) is low, both
halves of the H bridge are off (Table 1). When INx is high,
DIR controls the flow of current through the H-bridge. If
DIRx=0, current flows from OUTxA out to the coil and
back in through OUTxB. If DIRx=1, current flows from
OUTxB out to the coil and back in through OUTxA.
*C
1
*C
2
IN1
IN2
Gnd
Gnd
Gnd
Gnd
OUT2A
VS2
OUT1A
VS1
Table 1. Logic Control of H-Bridge
OUT1B OUT2B
Input Direction
Outputs
INX
DIRX
OUTxA OUTxB
COIL1
COIL2
0
1
1
X
0
0
1
0
0
0
1
Circular
Speedometer
* 0.047mF
Air Core
Gauge
1
3
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
