MC34932 Datasheet, PDF (12/24 Pages) Freescale Semiconductor, Inc – Dual 5.0 A H-Bridge

FUNCTIONAL DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
ENABLE INPUT/DISABLE INPUT 2 (EN/D2)
The EN/D2 pin performs the same function as D1 pin,
when it goes to a logic LOW the outputs are immediately tri-
stated. It is also used to place the device in a Sleep mode so
as to consume very low currents. When the EN/D2 pin
voltage is a logic LOW state, the device is in the Sleep mode.
The device is enabled and fully operational when the EN pin
voltage is logic HIGH. An internal pull-down resistor
maintains the device in Sleep mode in the event EN is driven
through a high-impedance I/O or an unpowered
microcontroller, or the EN/D2 input becomes disconnected.
FEEDBACK (FB)
The 34932 has a feedback output (FB) for monitoring of
H-Bridge high side output currents to facilitate closed-loop
operation for motor speed and torque control.
The FB pin provides current sensing feedback of the
H-Bridge high side drivers. When running in the forward or
reverse direction, a ground-referenced 0.24% of load current
is output to this pin. Through the use of an external resistor to
ground, the proportional feedback current can be converted
to a proportional voltage equivalent and the controlling
microcontroller can measure the current proportional voltage
with its analog-to-digital converter (ADC). This is intended to
provide the user with only first-order motor current feedback
for motor torque control. The resistance range for the linear
operation of the FB pin is 100 Ω < R_FB < 300 Ω.
If PWM-ing is implemented using the disable pin input
(only D1), a small filter capacitor (~1.0 µF) may be required
in parallel with the R_FB resistor to ground for spike
suppression
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
MC34932 - Functional Block Diagram
Analog Control & Protection
Current Sense
Voltage Regulation
Temperature Sense
Charge Pump
H-Bridge
Output Drivers
Gate Control Logic
Input Logic Control
Fault Logic
Protection Logic Control
OUT1 - OUT2
MCU Interface
Analog Control & Protection
Logic and Control
H-Bridge Output Drivers
Figure 10. Functional Internal Block Diagram
ANALOG CONTROL AND PROTECTION
CIRCUITRY:
An on-chip voltage regulator supplies the internal logic.
The charge pump provides gate drive for the H-Bridge
MOSFETs. The Current and Temperature sense circuitry
provides detection and protection for the output drivers.
Output undervoltage protection shuts down the MOSFETS.
GATE CONTROL LOGIC:
The 34932 is a monolithic H-Bridge Power IC designed
primarily for any low-voltage DC servo motor control
application within the current and voltage limits stated for the
device. Two independent inputs provide polarity control of
two half-bridge totem-pole outputs. Two independent disable
inputs are provided to force the H-Bridge outputs to tri-state
(high-impedance off-state).
H-BRIDGE OUTPUT DRIVERS: OUT1 AND OUT2
The H-Bridge is the power output stage. The current flow
from OUT1 to OUT2 is reversible and under full control of the
user by way of the Input Control Logic. The output stage is
designed to produce full load control under all system
conditions. All protective and control features are integrated
into the control and protection blocks. The sensors for current
and temperature are integrated directly into the output
MOSFET for maximum accuracy and dependability.
34932
12
Analog Integrated Circuit Device Data
Freescale Semiconductor