FUNCTIONAL DESCRIPTION
INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
The 17531A is a monolithic dual H-Bridge ideal for
portable electronic applications to control bipolar step motors
and brush DC motors such as those found in camera len
assemblies, camera shutters, and optical disk drives. The
device features an on-board charge pump, as well as built-in
shoot-through current protection and undervoltage
shutdown.
The 17531A has four operating modes: Forward, Reverse,
Brake, and Tri-Stated (High Impedance). The MOSFETs
comprising the output bridge have a total source +sink
RDS(ON) ≤ 1.2 Ω.
The 17531A can simultaneously drive two brush DC
motors or one bipolar step motor. The drivers are designed to
be PWM’ed at frequencies up to 200 kHz.
FUNCTIONAL TERMINAL DESCRIPTION
LOGIC SUPPLY (VDD)
MOTOR DRIVE POWER SUPPLY (VM1 AND VM2)
The VDD terminal carries the logic supply voltage and
current into the logic sections of the IC. VDD has an
undervoltage threshold. If the supply voltage drops below the
undervoltage threshold, the output power stage switches to a
tri-state condition. When the supply voltage returns to a level
that is above the threshold, the power stage automatically
resumes normal operation according to the established
condition of the input terminals.
The VM terminals carry the main supply voltage and
current into the power sections of the IC. This supply then
becomes controlled and/or modulated by the IC as it delivers
the power to the loads attached between the OUTput
terminals. All VM terminals must be connected together on
the printed circuit board.
CHARGE PUMP (C1L AND C1H, C2L AND C2H)
These two pairs of terminals, the C1L and C1H and the
C2L and C2H, connect to the external bucket capacitors
required by the internal charge pump. The typical value for
the bucket capacitors is 0.1 µF.
LOGIC INPUT CONTROL (IN1A, IN1B, IN2A, AND
IN2B)
These logic input terminals control each H-Bridge output.
IN1A logic HIGH = OUT1A HIGH. However, if all inputs are
taken HIGH, the outputs bridges are both tri-stated (refer to
Table 6, Truth Table, page 9).
PREDRIVER POWER SUPPLY (CRES)
The CRES terminal is the output of the internal charge
pump. Its output voltage is approximately three times of VDD
voltage. The VCRES voltage is power supply for the internal
predriver circuit of H-Bridges.
POWER SAVE (PSAVE)
The PSAVE terminal is a HIGH = TRUE power save mode
input. When PSAVE = HIGH, all H-Bridge outputs (OUT1A,
OUT1B, OUT2A, and OUT2B) are tri-stated (High-Z),
regardless of logic inputs (IN1A, IN1B, IN2A, and IN2B)
states, and the internal charge pump and low voltage
detection current are shut off to save power.
POWER GROUND (PGND)
Power ground terminals. They must be tied together on the
PCB.
LOGIC GROUND (LGND)
H-BRIDGE OUTPUT (OUT1A, OUT1B, OUT2A, AND
OUT2B)
Logic ground terminal.
These terminals provide connection to the outputs of each
of the internal H-Bridges (see Figure 2, 17531A Simplified
Internal Block Diagram, page 2).
17531A
Analog Integrated Circuit Device Data
Freescale Semiconductor
10
FREESCALE [ Freescale ]
