3974
DMOS DUAL FULL-BRIDGE PWM MOTOR DRIVER
Designed for pulse-width modulated (PWM) current control
of two dc motors, the A3974SED is capable of output currents to
±1.5 A and operating voltages to 50 V. Internal fixed off-time
PWM current-control timing circuitry can be programmed via a
serial interface to operate in slow, fast, and mixed current-decay
modes.
V
BB1
Independant ENABLE input terminals are provided for use in
NC
STROBE
CLOCK
NC
7
8
9
39
38
37
36
35
34
33
32
31
30
29
controlling the speed and torque of each dc motor with externally
CP2
CP1
CP
applied PWM control signals.
PROGRAM
PWM TIMER
LOGIC
Synchronous rectification circuitry allows the load current to
DATA 10
flow through the low rDS(on) of the DMOS output driver during
the current decay. This feature will eliminate the need for
external clamp diodes in most applications, saving cost and
external component count, while minimizing power dissipation.
Internal circuit protection includes thermal shutdown with
hysteresis, undervoltage monitoring of VDD and the charge
pump, and crossover-current protection. Special power-up
sequencing is not required.
GND
GND
GND
GND
GND
GND
OSC
SLEEP
11
12
13
14
15
16
17
REF
1
2
÷
÷
REF
PROGRAM
PWM TIMER
LOGIC
LOGIC
SUPPLY
VREG
VDD
NC
NC
The A3974SED is supplied in a 44-lead plastic PLCC with
four copper batwing tabs for maximum heat dissipation. The
power tabs are at ground potential and need no electrical isola-
tion.
V
BB2
Dwg. PP-073
ABSOLUTE MAXIMUM RATINGS
FEATURES
at TA = +25°C
■ ±1.5 A, 50 V Continuous Output Rating
■ Low rDS(on) DMOS Output Drivers
Load Supply Voltage, VBB ............................ 50 V
Output Current, IOUT .................................. ±1.5 A
Logic Supply Voltage, VDD .......................... 7.0 V
Logic Input Voltage Range, VIN
■
Programmable Slow, Fast, and Mixed Current-Decay Modes
■ Serial-Interface Controls Chip Functions
■ Synchronous Rectification for Low Power Dissipation
■ Internal UVLO and Thermal Shutdown Circuitry
■ Crossover-Current Protection
Continous ................... -0.3 V to VDD + 0.3 V
tW < 30 ns ................... -1.0 V to VDD + 1.0 V
Reference Voltage, VREF ................................. 3 V
Sense Voltage (dc), VS
Continous .............................................. 0.5 V
tW < 1 µs ................................................ 2.5 V
Package Power Dissipation, PD .................. 3.9 W
Operating Temperature Range,
■ Sleep and Idle Modes
Selection Guide
TA ......................................... -20°C to +85°C
Junction Temperature, TJ ......................... +150°C
Storage Temperature Range,
Part Number
A3974SED-T
A3974SEDTR-T
Pb-free*
Yes
Package
44-pin PLCC
44-pin PLCC
Packing
27 per tube
450 per reel
Yes
*Pb-based variants are being phased out of the product line. The variants cited in
this footnote are in production but have been determined to be LAST TIME BUY.
This classification indicates that sale of this device is currently restricted
to existing customer applications. The variants should not be purchased for new
design applications because obsolescence in the near future is probable. Samples
are no longer available. Status change: October 31, 2006. Deadline for LAST TIME
BUY orders: April 27, 2007. Th.ese variants include: A3974SED and A3974SEDTR.
TS ....................................... -55°C to +150°C
Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any set
of conditions, do not exceed the specified current rating
or a junction temperature of 150°C.