MC34921 Datasheet, PDF (18/36 Pages) List of Unclassifed Manufacturers – Configurable Motor Driver IC with Power Supplies

FUNCTIONAL DESCRIPTION
Introduction
FUNCTIONAL DESCRIPTION
INTRODUCTION
The serial interface of the MC34921 is a three input, one
output interface similar to a Serial Peripheral Interface (SPI)
port in general form, but different in specific clocking
requirements due to the fact that an A/D converter cannot
reliably run without a continuous clock. The 34921 serial
interface communicates to a microcontroller unit (MCU) at up
to 16 MHz. The serial signals are SCLK, CE, MOSI, and
MISO. The SCLK signal pin requires a free-running clock (up
to 16 MHz) which is provided by the MCU. This signal is
required to ensure proper operation of both the ADC and the
reset timer circuitry. The serial data transfers between the
MCU and the 34921 via the MOSI and MISO terminals. The
serial data from the MCU is handled in the MC34921 via two
input registers -- the NORMAL input register contains bits
controlling the motor drivers as well as the A/D converter, and
the CONFIG register contains bits relating to the general
configuration setup of the device. The MC34921 also has two
output registers -- the NORMAL output register reports A/D
conversion data as well as digital encoder data, and the IREQ
output register reports under voltage, temperature, and other
device status data.
FUNCTIONAL TERMINAL DESCRIPTION
GROUND (GND)
Main ground. It is used for the B+ filters and motor filter
grounds, as well as the ground return for external
components which are used with the linear and switching
regulators.
COVER VOLTAGE OUTPUT SELECT (VCORE SELECT)
This terminal is used to select the output voltage provided
by the VCORE linear regulator. The VCORE Select potential
is latched in during the MC34921's power-on sequence. The
MC34921 will not respond to changes in VCORE Select after
power up.
Unipolar Step A/DC Motor C Output A (SA/CDCMA)
A low-side driver output is configurable for either stepper
motor control (SA) or C DC motor (as CDCMA, which
requires an external hardwire to pin 63) via the serial I/O. The
driver is PWM controlled via the CPWMA/CDCPWM pin, and
direction controlled via the Serial I/O. It includes an active
voltage clamp, current limit, and thermal shutdown
protection.
Unipolar Step A/DC Motor C Output B (SA/CDCMB)
A low-side driver output is configurable for either stepper
motor control (SA) or C DC motor (as CDCMB, it requires
external hardwire to pin 61) via the serial I/O. The driver is
PWM controlled via the CPWMA/CDCPWM pin, and
direction controlled via the Serial I/O. It includes active
voltage clamp, current limit, and thermal shutdown
protection.
Unipolar Step B/LOW-SIDE 1 (SB/LSOUT1)
A low-side driver output is configurable for either stepper
motor control (SB) or as a general purpose low-side driver
(LSOUT1) via the serial I/O. The SB is PWM controlled via
the CPWMB pin. The direction and LSOUT1 are controlled
via the serial I/O. It includes active voltage clamp, current
limit and thermal shutdown protection.
Unipolar Step B/LOW-SIDE 2 (SB/LSOUT2)
A low-side driver output is configurable for either stepper
motor control (SB) or as a general purpose low-side driver
(LSOUT2) via the serial I/O. The SB is PWM controlled via
the CPWMB pin. The direction and LSOUT2 are controlled
via the serial I/O. It includes active voltage clamp, current
limit and thermal shutdown protection.
POWER SUPPLY INPUT (B+)
This is the main power supply input for the regulators and
DC motor drivers.
3.3 V SWITCHING REGULATOR SWITCH OUTPUT
(3.3 V SWITCH)
The high-side driver output is used for the 3.3v switching
regulator. It uses the internal 200KHZ clock.
3.3 V REGULATOR FEEDBACK (3.3 V)
This terminal is the error amp feedback for the 3.3v
switching regulator. It is also the output point for the 3.3v
switching supply.
CORE VOLTAGE REGULATOR INPUT (VCORE SUPPLY)
The input voltage terminal for the VCORE linear supply,
which is usually provided by externally hardwiring the 3.3v
switching regulator output.
CORE VOLTAGE REGULATOR OUTPUT (VCORE)
The output terminal of the VCORE linear regulator.
Voltage options of 1.5v, 1.8v, or 2.5v are set by the potential
of the VCORE Select pin at power up. It features current limit
and thermal shutdown protection. It is typically used to supply
a micro processor core or embedded DRAM.
34921
18
Analog Integrated Circuit Device Data
Freescale Semiconductor