3974_1 Datasheet, PDF (1/12 Pages) Allegro MicroSystems – DMOS DUAL FULL-BRIDGE PWM MOTOR DRIVER

3974
DMOS DUAL FULL-BRIDGE PWM MOTOR DRIVER
NC 7
STROBE 8
CLOCK 9
DATA 10
GND 11
GND 12
GND 13
REF1 14
÷
REF2 15
÷
LOGIC
SUPPLY
16
VDD
NC 17
VBB1
PROGRAM
PWM TIMER
LOGIC
PROGRAM
PWM TIMER
LOGIC
VBB2
39 NC
38 CP2
37 CP1
36 CP
35 GND
34 GND
33 GND
32 OSC
31 SLEEP
30 VREG
29 NC
Dwg. PP-073
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.
Independant ENABLE input terminals are provided for use in
controlling the speed and torque of each dc motor with externally
applied PWM control signals.
Synchronous rectification circuitry allows the load current to
flow through the low r_DS(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 V_DD and the charge
pump, and crossover-current protection. Special power-up
sequencing is not required.
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.
ABSOLUTE MAXIMUM RATINGS
at T_A = +25°C
Load Supply Voltage, V_BB ............................ 50 V
Output Current, I_OUT .................................. ±1.5 A
Logic Supply Voltage, V_DD .......................... 7.0 V
Logic Input Voltage Range, V_IN
Continous ................... -0.3 V to V_DD + 0.3 V
t_W < 30 ns ................... -1.0 V to V_DD + 1.0 V
Reference Voltage, V_REF ................................. 3 V
Sense Voltage (dc), V_S
Continous .............................................. 0.5 V
t_W < 1 µs ................................................ 2.5 V
Package Power Dissipation, P_D .................. 3.9 W
Operating Temperature Range,
T_A ......................................... -20°C to +85°C
Junction Temperature, T_J ......................... +150°C
Storage Temperature Range,
T_S ....................................... -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.
FEATURES
■ ±1.5 A, 50 V Continuous Output Rating
■ Low r_DS(on) DMOS Output Drivers
■ 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
■ Sleep and Idle Modes
Selection Guide
Part Number Pb-free*
Package
Packing
A3974SED-T
Yes
44-pin PLCC
27 per tube
A3974SEDTR-T
Yes
44-pin PLCC
450 per reel
*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.