SA03 Cirrus Logic Inc, SA03 Datasheet - Page 4

• Manufacturer Part Number: SA03
• Description: IC PWM AMP 100V 30A 12-PWRDIP
• Manufacturer: Cirrus Logic Inc
• Series: Apex Precision Power™r

Specifications of SA03

• Mfg Application Notes: SAxx App Note 34
• Applications: DC Motor Driver
• Number Of Outputs: 1
• Current - Output: 30A
• Voltage - Load: 16 V ~ 100 V
• Voltage - Supply: 16 V ~ 100 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: 12-DIP Module
• For Use With: 598-1456 - EVALUATION KIT FOR SA03
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Other names: 598-1452; SA03

SA03
GENERAL
to Application Note 1 "General Operating Considerations" for
helpful information regarding power supplies, heat sinking
and mounting. Visit www.Cirrus.com for design tools that help
automate pwm filter design; heat sink selection; Apex Precision
Power’s complete Application Notes library; Technical Seminar
Workbook; and Evaluation Kits.
CLOCK CIRCUIT AND RAMP GENERATOR
proximately 45kHz. The CLK OUT pin will normally be tied
to the CLK IN pin. The clock is divided by two and applied to
an RC network which produces a ramp signal at the –PWM/
RAMP pin. An external clock signal can be applied to the CLK
IN pin for synchronization purposes. If a clock frequency lower
than 45kHz is chosen an external capacitor must be tied to the
–PWM/RAMP pin. This capacitor, which parallels an internal
capacitor, must be selected so that the ramp oscillates 4 volts
p-p with the lower peak 3 volts above ground.
PWM INPUTS
comparator. When +PWM > -PWM then A OUT > B OUT. A
motion control processor which generates the pwm signal can
drive these pins with signals referenced to GND.
PROTECTION CIRCUITS
is also a fixed internal current limit which senses only the high
side current. It is nominally set to 140% of the continuous
rated output current. Should either of the outputs be shorted
to ground the high side current limit will latch off the output
transistors. Also, the temperature of the output transistors is
continually monitored. Should a fault condition occur which
raises the temperature of the output transistors to 165°C
the thermal protection circuit will activate and also latch off
the output transistors. In either case, it will be necessary to
remove the fault condition and recycle power to V
to restart the circuit.
CURRENT LIMIT
SENSE B. The two pins can be shorted in the voltage mode
connection but both must be used in the current mode con-
nection (see figures A and B). It is recommended that R
resistors be non-inductive. Load current flows in the I SENSE
pins. To avoid errors
due to lead lengths
connect the I LIMIT/
SHDN pin directly
to the R
tors (through the
filter network and
shutdown divider re-
sistor) and connect
the R
directly to the GND
pin.
4
Please read Application Note 30 on "PWM Basics". Refer
The clock frequency is internally set to a frequency of ap-
The full bridge driver may be accessed via the pwm input
In addition to the externally programmable current limit there
There are two load current sensing pins, I SENSE A and I
LIMIT
LIMIT
resistors
resis-
FIGURE A. CURRENT LIMIT WITH
SHUTDOWN VOLTAGE MODE.
I LIMIT/SHDN
I SENSE A
I SENSE B
R
C
FILTER
FILTER
R
LIMIT
1K
R
SHDN
SHUTDOWN
CC
SIGNAL
and +V
LIMIT
P r o d u c t T e c h n o l o g y F r o m
S
switching circuits it may be difficult to determine the true noise
amplitude without careful attention to grounding of the oscil-
loscope probe. Use the shortest possible ground lead for the
probe and connect exactly at the GND terminal of the amplifier.
Suggested starting values are C
culated by:
maximum desired current. In current mode the required value
of each R
divided down by 2 (see Figure B). If R
divide down the sense voltage. The shutdown divider network
will also have an effect on the filtering circuit.
BYPASSING
proper operation. Failure to do so can cause erratic and low
efficiency operation as well as excessive ringing at the out-
puts. The Vs supply should be bypassed with at least a 1µF
ceramic capacitor in parallel with another low ESR capacitor
of at least 10µF per amp of output current. Capacitor types
rated for switching applications are the only types that should
be considered. The bypass capacitors must be physically
connected directly to the power supply pins. Even one inch of
lead length will cause excessive ringing at the outputs. This
is due to the very fast switching times and the inductance of
the lead connection. The bypassing requirements of the Vcc
supply are less stringent, but still necessary. A .1µF to .47µF
ceramic capacitor connected directly to the Vcc pin will suffice.
STARTUP CONDITIONS
driven by bootstrap circuit and charge pump arrangement. In
order for the circuit to produce a 100% duty cycle indefinitely
the low side of each half bridge circuit must have previously
been in the ON condition. This means, in turn, that if the input
signal to the SA03 at startup is demanding a 100% duty cycle,
the output may not follow the command and may be in a tri-
state condition. The ramp signal must cross the input signal
at some point to correctly determine the output state. After the
ramp crosses the input signal level one time, the output state
will be correct thereafter.
FIGURE B. CURRENT LIMIT WITH
SHUTDOWN CURRENT MODE.
I LIMIT/SHDN
I SENSE A
I SENSE B
The required value of R
where R
Adequate bypassing of the power supplies is required for
The high side of the all N channel output bridge circuit is
R
LIMIT
LIMIT
LIMIT
R
C
is 2 times this value since the sense voltage is
FILTER
FILTER
is the required resistor value, and I
R
1K
1K
LIMIT
R
LIMIT
LIMIT
= .1 V / I
variably be found at the I SENSE
pins. The noise spikes could trip
the current limit threshold which
is only 100 mV. R
TER
reduce the switching noise well
below 100 mV to prevent false
R
in voltage mode may be cal-
SHDN
Switching noise spikes will in-
FILTER
should be adjusted so as to
SHUTDOWN
SIGNAL
LIMIT
SHDN
= .01uF, R
is used it will further
current limiting.
The sum of the
DC level plus the
noise peak will
determine the
current limiting
value. As in most
FILTER
FILTER
LIMIT
and C
= 5k .
SA03U
is the
FIL-