APEX MICROTECHNOLOGY CORPORATION · TELEPHONE (520) 690-8600 · FAX (520) 888-3329 · ORDERS (520) 690-8601 · EMAIL prodlit@apexmicrotech.com

FEATURE

· HIGH FREQUENCY SWITCHING -- 200 kHz

· WIDE SUPPLY RANGE--16-200V

· 15A CONTINUOUS TO 65°C CASE

· 3 PROTECTION CIRCUITS

· ANALOG OR DIGITAL INPUTS

· SYNCHRONIZED OR EXTERNAL OSCILLATOR

· FLEXIBLE FREQUENCY CONTROL

APPLICATIONS

· REACTIVE LOADS

· LOW FREQUENCY SONAR

· LARGE PIEZO ELEMENTS

· OFF-LINE DRIVERS

· C-D WELD CONTROLLER

DESCRIPTION

The SA12 is a pulse width modulation amplifier that can

supply 3000W to the load. An internal 400kHz oscillator re-

quires no external components. The clock input stage divides

the oscillator frequency by two, which provides the 200 kHz

switching frequency. External oscillators may also be used to

lower the switching frequency or to synchronize multiple ampli-

fiers. Current sensing is provided for each half of the H-bridge

giving amplitude and direction data. A shutdown input turns

off all four drivers of the H-bridge output. A high side current

limit and the programmable low side current limit protect the

amplifier from shorts to supply or ground in addition to load

shorts. The H-bridge output MOSFETs are protected from

thermal overloads by directly sensing the temperature of the

die. The 12-pin hermetic MO-127 power package occupies
only 3 square inches of board space.

BLOCK DIAGRAM AND TYPICAL APPLICATION
TORQUE MOTOR DRIVER

EXTERNAL CONNECTIONS

12-PIN POWER DIP

PACKAGE STYLE CR

APEX MICROTECHNOLOGY CORPORATION · 5980 NORTH SHANNON ROAD · TUCSON, ARIZONA 85741 · USA · APPLICATIONS HOTLINE: 1 (800) 546-2739

ABSOLUTE MAXIMUM RATINGS

SPECIFICATIONS

SA12

ABSOLUTE MAXIMUM RATINGS

SUPPLY VOLTAGE, +V

200V

SUPPLY VOLTAGE, V

16V

POWER DISSIPATION, internal

250W

TEMPERATURE, pin solder - 10s

300°C

TEMPERATURE, junction

150°C

TEMPERATURE, storage

65 to +150°C

OPERATING TEMPERATURE RANGE, case

55 to +125°C

INPUT VOLTAGE, +PWM

0 to +11V

INPUT VOLTAGE, PWM

0 to +11V

INPUT VOLTAGE, I

LIM

0 to +10V

The SA12 is constructed from MOSFET transistors. ESD handling procedures must be observed.
The internal substrate contains beryllia (BeO). Do not break the seal. If accidentally broken, do not crush,

machine, or subject to temperatures in excess of 850°C to avoid generating toxic fumes.

CAUTION

NOTES: 1.

Each of the two active output transistors can dissipate 125W.

Unless otherwise noted: T

= 25°C, V

, V

at typical specification.

Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power

dissipation to achieve high MTTF. For guidance, refer to the heatsink data sheet.

Guaranteed but not tested.

SPECIFICATIONS

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

CLOCK (CLK)
CLK OUT, high level

OUT

1mA

4.8

5.3

CLK OUT, low level

OUT

1mA

FREQUENCY

392

400

408

kHz

RAMP, center voltage

RAMP, P-P voltage

CLK IN, low level

CLK IN, high level

3.7

5.4

OUTPUT
TOTAL R

EFFICIENCY, 10A output

= 200V

SWITCHING FREQUENCY

OSC in ÷ 2

196

200

204

kHz

CURRENT, continuous

65°C case

CURRENT, peak

POWER SUPPLY
VOLTAGE, V

Full temperature range

120

200

VOLTAGE, V

Full temperature range

CURRENT, V

OUT

= 0

CURRENT, V

CC,

shutdown

CURRENT, V

No Load

200

LIM

/SHUTDOWN

TRIP POINT

110

INPUT CURRENT

100

THERMAL

RESISTANCE, junction to case

Full temperature range, for each die

°C/W

RESISTANCE, junction to air

Full temperature range

°C/W

TEMPERATURE RANGE, case

Meets full range specifications

+85

°C

APEX MICROTECHNOLOGY CORPORATION · 5980 NORTH SHANNON ROAD · TUCSON, ARIZONA 85741 · USA · APPLICATIONS HOTLINE: 1 (800) 546-2739

Switching noise spikes will in-

variably be found at the I SENSE
pins. The noise spikes could trip the
current limit threshold which is only
100 mV. R

FILTER

and C

FILTER

should

be adjusted so as to reduce the
switching noise well below 100 mV

to prevent false current
limiting. The sum of the
DC level plus the noise
peak will determine the
current limiting value.
As in most switching
circuits it may be dif-
ficult to determine the

true noise amplitude without careful attention to grounding
of the oscilloscope 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

FILTER

= .01uF,

FILTER

= 5k .

The required value of R

LIMIT

in voltage mode may be cal-

culated by:

LIMIT

= .1 V / I

LIMIT

where R

LIMIT

is the required resistor value, and I

LIMIT

is the

maximum desired current. In current mode the required value
of each R

LIMIT

is 2 times this value since the sense voltage is

divided down by 2 (see Figure B). If R

SHDN

is used it will further

divide down the sense voltage. The shutdown divider network
will also have an effect on the filtering circuit.

BYPASSING

Adequate bypassing of the power supplies is required for

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.

MODULATION RANGE

The high side of the all N channel H-bridge is driven by a

bootstrap circuit. For the output circuit to switch high, the low
side circuit must have previously been switched on in order to
charge the bootstrap capacitor. Therefore, if the input signal to
the SA12 demands a 100% duty cycle upon start-up the output
will not follow and will be in a tri-state (open) condition. The
ramp signal must cross the input signal at some point to cor-
rectly determine the output state. After the ramp crosses the
input signal one time the output state will be correct thereafter.
In addition, if during normal operation the input signal drives
the SA12 beyond its linear modulation range (approximately
95%) the output will jump to 100% modulation.

GENERAL

Please read Application Note 30 on "PWM Basics". Refer

to Application Note 1 "General Operating Considerations" for
helpful information regarding power supplies, heat sinking and
mounting. Visit www.apexmicrotech.com for design tools that
help automate pwm filter design; heat sink selection; Apex's
complete Application Notes library; Technical Seminar Work-
book; and Evaluation Kits.

CLOCK CIRCUIT AND RAMP GENERATOR

The clock frequency is internally set to a frequency of ap-

proximately 400kHz. 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
400kHz 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

The full bridge driver may be accessed via the pwm input

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

A fixed internal current limit senses the high side current.

Should either of the outputs be shorted to ground the high
side current limit will latch off the output transistors. The tem-
perature of the output transistors is also monitored. Should a
fault condition raise the temperature of the output transistors
to 165°C the thermal protection circuit will latch off the output
transistors. The latched condition can be cleared by either
recycling the V

power or by toggling the I LIMIT/SHDN input

with a 10V pulse. See Figures A and B. The outputs will remain
off as long as the shutdown pulse is high (10V).

When supply voltage is over 100V, these circuits may not

protect the FET switches in the case of short circuits directly
at the pins of the amplifier. However, a small inductance be-
tween the amplifier and the short circuit will limit current rise
time and the protection circuits will be effective. A pair of 12
inch wires is adequate inductance.

CURRENT LIMIT

There are two load current

sensing pins, I SENSE A and
I SENSE B. The two pins can
be shorted in the voltage
mode connection but both
must be used in the current
mode connection (see figures
A and B). It is recommended
that R

LIMIT

resistors be non-in-

ductive. 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

LIMIT

resistors (through

the filter network and shutdown divider resistor) and connect
the R

LIMIT

resistors directly to the GND pin.

OPERATING

CONSIDERATIONS

SA12

This data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible inaccuracies or omissions. All specifications are subject to change without notice.

Part Number SA12