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34923 Schematic ( PDF Datasheet ) - Freescale Semiconductor

Teilenummer 34923
Beschreibung Full-Bridge PWM Motor Driver
Hersteller Freescale Semiconductor
Logo Freescale Semiconductor Logo 




Gesamt 16 Seiten
34923 Datasheet, Funktion
www.DataSheet4U.com
Freescale Semiconductor, Inc.
MOTOROLA
Order this document from Analog Marketing: MC34923/D
Rev 0, 05/2003
SEMICONDUCTOR TECHNICAL DATA
Preliminary Information
Full-Bridge PWM Motor Driver
Designed with Motorola’s advanced SMARTMOS, the 34923 is designed for
pulse-width modulated (PWM) current control of DC motors. It is capable of
continuous output currents up to 2.0 A and operating voltages of up to 45 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.
DIR and PWM/ENABLE input pins are provided for use in controlling the
speed and direction of a DC motor with externally applied PWM-control
signals. The PWM/ENABLE input can be programmed via the serial port to
PWM the bridge in fast or slow current decay. Internal synchronous
rectification control circuitry is provided to reduce power dissipation during
PWM operation.
Internal circuit protection includes thermal shutdown with hysteresis and
crossover-current protection. A special power-up sequencing is not required.
34923
FULL-BRIDGE PWM MOTOR
DRIVER
Features
• ±2.0 A, 45 V Continuous Output Rating
• Low RDS(ON) Outputs (270 m, typical)
• Programmable Mixed, Fast, and Slow Current-Decay Modes
• Serial Interface Controls Chip Functions
• Synchronous Rectification for Low Power Dissipation
• Internal Undervoltage Lockout Thermal Shutdown Circuitry
• Crossover-Current Protection
DW SUFFIX
24-LEAD SOICW
CASE 751E-04
ORDERING INFORMATION
Device
Temperature
Range (TA)
Package
MC34923DW/R2 -40 to 125°C
24 SOICW
34923 Simplified Application Diagram
5.0 V
5.0 V
34923
MCU
Serial
Port
PWMMODE
DIR DCMA
PWM/ENABLE
CLOCK
DATA
STROBE
OSC
DCMB
GND
DC
Motor
This document contains information on a product under development.
Motorola reserves the right to change or discontinue this product without notice.
© Motorola, Inc. 2003
For More Information On This Product,
Go to: www.freescale.com






34923 Datasheet, Funktion
Freescale Semiconductor, Inc.
STATIC ELECTRICAL CHARACTERISTICS (continued)
Characteristics noted under conditions TA = 25°C, VBB = 45 V, VDD = 5.0 V, VSENSE = 0.5 V, and fPWM < 50 kHz unless otherwise
noted.
Characteristic
Symbol
Min
Typ
Max Unit
CONTROL LOGIC (continued)
Reference Divider Ratio
Bit D14 = High
Bit D14 = Low
––
9.9 10 10.2
4.95 5.0 5.05
Thermal Shutdown Temperature
TJ – 165 – °C
Thermal Shutdown Hysteresis
TJ – 15 – °C
Undervoltage Lockout Enable Threshold
Increasing VDD
UVLO
V
3.90 4.2 4.45
Undervoltage Lockout Hysteresis
UVLO 0.05 0.10
–V
Logic Supply Current
fPMW < 50 kHz
Sleep Mode, Inputs <0.5 V
IDD mA
– 6.0 10
– – 2.0
34923
6
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
For More Information On This Product,
Go to: www.freescale.com

6 Page









34923 pdf, datenblatt
Freescale Semiconductor, Inc.
PWM Blank Timer
When a source driver turns on, a current spike occurs owing
to the reverse recovery currents of the clamp diodes and/or
switching transients related to distributed capacitance in the
load. To prevent this current spike from erroneously resetting
the source-enable latch, the sense comparator is blanked. The
blank timer runs after the off-time counter (see bits D2–D6) to
provide the programmable blanking function. The blank timer is
reset when PWM/ENABLE is chopped or DIR is changed. For
external PWM control, a DIR change or PWM/ENABLE on will
trigger the blanking function.
Synchronous Rectification
When a PWM off cycle is triggered, either by an PWM/
ENABLE chop command or internal fixed off-time cycle, load
current will recirculate according to the decay mode selected by
the control logic. The 34923 synchronous rectification feature
will turn on the opposite pair of outputs during the current decay
and effectively short out the body diodes with the low RDS(ON)
driver. This will reduce power dissipation significantly and can
eliminate the need for external Schottky diodes.
Synchronous rectification can be configured in active mode,
passive mode, or disabled via the serial port (bits D11 and
D12).
The active or passive mode selection has no impact in slow-
decay mode. With synchronous rectification enabled, the slow-
decay mode serves as an effective brake mode.
Current Regulation
Load current is regulated by an internal fixed off-time PWM
control circuit. When the outputs of the H-bridge are turned on,
the current increases in the motor winding until it reaches a trip
value determined by the external sense resistor (RS), the
applied analog reference voltage (VREF), the SPAN logic level,
and serial data bit D16:
When SPAN = D16, ITRIP = VREF/10RS
When SPAN D16, ITRIP = VREF/5RS
At the trip point, the sense comparator resets the source-
enable latch, turning off the source driver. The load inductance
then causes the current to recirculate for the serial-port-
programmed fixed off-time period. The current path during
recirculation is determined by the configuration of slow/mixed
current-decay mode (D17) and the synchronous rectification
control bits (D11 and D12).
Internal PWM (Current Mode) PWM Frequency
The internal PWM opeating frequency is set by the sum of
“Off Time”, as determined by bits D2 through D6, “Blank Time”,
as determined by bits D0 and D1, and the time constant of the
motor.
34923
12
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
For More Information On This Product,
Go to: www.freescale.com

12 Page





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