Pulse Width Modulation Amplifiers

Pulse Width Modulation Amplifiers
SA09
SA09
SA09
Pulse Width Modulation Amplifiers
FEATURES
DESCRIPTION
The SA09 amplifier is a 40 volt, 500kHz PWM amplifier. The full bridge output circuit provides 5 amps of
continuous drive current for applications as diverse as
high fidelity audio and brush type motors. Clock output
and input pins can be used for synchronization with
other amplifiers or an externally generated clock. Direct
access to the pwm input is provided for connection to
digital motion control circuits. Protection circuits guard
against thermal overloads as well as shorts to supply
or ground. The current limit is programmable with one
or two external resistors depending on the application.
A shutdown input disables all output bridge drivers.
The 18 pin steel package is hermetically sealed.
♦ 500kHz SWITCHING
♦ FULL BRIDGE OUTPUT 5-40V (80V P-P)
♦ 5A OUTPUT
♦ 1 IN2 FOOTPRINT
♦ FAULT PROTECTION
♦ SHUTDOWN CONTROL
♦ SYNCHRONIZABLE CLOCK
♦ HERMETIC PACKAGE
APPLICATIONS
♦ HIGH FIDELITY AUDIO AMPLIFIER
♦ BRUSH TYPE MOTOR CONTROL
♦ VIBRATION CANCELLING AMPLIFIER
BLOCK DIAGRAM
AND TYPICAL APPLICATION CONNECTIONS HIGH FIDELITY AUDIO
5V OUT
THERMAL,
SHORT
CIRCUIT
PROTECT.
+VS
+PWM
1
13
Vcc
5
10
6
RAMP/–PWM
B
R
I
D
G
E
18K
100pF
CLK OUT
18
OSC
CLK IN
CLK/2
D
R
I
V
E
R
REG.
5V
A OUT
12
B OUT
14
5V
ILIM/SHDN
17
16
GND
LOAD
R FILTER
R SHDN
C FILTER
1K
I SENSE A
7
SA09
11
15
I SENSE B
R LIMIT
SIGNAL
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SA09U
Copyright © Apex Microtechnology, Inc. 2012
(All Rights Reserved)
OCT 2012
1
SA09U REVD
SA09
EXTERNAL CONNECTIONS
5V OUT
NC
NC
NC
1
2
3
4
18
17
16
15
CLK OUT*
CLK IN
ILIM/SHDN
ISENSE B
+PWM
RAMP/-PWM
GND
NC
NC
5
6
7
8
9
14
13
12
11
10
B OUT
+VS
RLIMIT*
+
A OUT
ISENSE A
VCC RLIMIT*
+
18-pin DIP
PACKAGE STYLE EL
* See text.
Case tied to Pin 7. Allow no current in case. Bypassing of supplies is required. If +PWM > RAMP then A OUT > B OUT.
1. CHARACTERISTICS AND SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS
Parameter
Symbol
Min
Max
Units
SUPPLY VOLTAGE, +Vs to GND, 10mS surge
60
V
SUPPLY VOLTAGE, +VCC to GND
16
V
OUTPUT CURRENT, peak
7.5
A
POWER DISSIPATION, internal (Note 3)
80
W
TEMPERATURE, pin solder, 10s
350
°C
TEMPERATURE, junction (Note 1)
150
°C
TEMPERATURE, storage
−65
150
°C
OPERATING TEMPERATURE RANGE, case
−55
125
°C
INPUTS
−0.4
+5.4
V
CAUTION
The SA09 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.
2
SA09U
SA09
SPECIFICATIONS
Min
Typ
Max
Units
CLOCK OUT
Parameter (Note 1)
Test Conditions
0.98
1
1.02
MHz
CLOCK OUT, high level
4.7
5.3
V
0.2
V
5.012
V
CLOCK OUT, low level
5V OUT
0
LOAD ≤ 5mA
4.988
5
OUTPUT
EFFICIENCY, 5A output
VS = 40V
SWITCHING FREQUENCY
CURRENT, continuous
CURRENT, peak (Note 4)
100 ms, 10% duty cycle
94
%
500
kHz
5
A
7
A
RDS(ON) (Note 4)
0.55
Ω
16
V
40
V
POWER SUPPLY
VOLTAGE, VCC
Full temperature range
10
12
VOLTAGE, VS
Full temperature range
5
CURRENT, VCC
Switching
50
mA
CURRENT, VS
Switching, no load
90
mA
INPUTS (Note 4)
ILIM /SHDN, trip point
90
110
mV
–PWM, +PWM, low level
0
0.8
V
–PWM, +PWM, high level
2.7
VCC
V
CLOCK IN, low level
0
0.3
V
CLOCK IN, high level
3
5.6
V
3.5
°C/W
THERMAL (Note 2)
RESISTANCE, junction to case
Full temperature range
RESISTANCE, junction to air
Full temperature range
TEMPERATURE RANGE, case
Meets full range specifications
15
-25
°C/W
85
°C
NOTES:
1. All Min/Max characteristics and specifications are guaranteed over the Specified Operating Conditions. Typical performance characteristics and specifications are derived from measurements taken
at typical supply voltages and TC = 25°C.
2. 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 datasheet.
3. 40W in each of the two active output transistors on at any one time.
4. Min max values guaranteed but not tested.
SA09U
3
SA09
CLOCK LOADING
20
10
EACH ACTIVE
OUTPUT TRANSISTOR
0
50
25
75
100
CASE TEMPERATURE, (°C)
125
100.5
98.5
98.0
F NOMINAL = 1M
100
99.5
99.0
98.5
98.0
1K
10K
CLOCK LOAD RESISTANCE, (Ω)
–50 –25 0
25 50 75 100 125
CASE TEMPERATURE, (°C)
DUTY CYCLE VS ANALOG INPUT
CONTINUOUS OUTPUT
100
B OUTPUT
1.0
5
4
3
2
80
4
DUTY CYCLE, (%)
2
3
2
60
40
20
1
A OUTPUT
90
80
70
60
50
40
0
100
200
300
400
500
SWITCHING FREQUENCY, F (kHz)
NORMALIZED Vcc QUIESCENT CURRENT, (%)
Vcc QUIESCENT CURRENT
100
Vs QUIESCENT VS FREQUENCY
90
70
60
50
40
30
20
10
0
0
200
300
400
100
500
SWITCHING FREQUENCY, F (kHz)
150
1
Vcc QUIESCENT CURRENT
Vcc = 12V
F = 500kHz
100
NORMAL OPERATION
75
50
SHUTDOWN OPERATION
25
–50 –25
0 25 50 75 100 125
CASE TEMPERATURE, T C (°C)
120
2
3
ANALOG INPUT, (V)
4
Vs QUIESCENT VS VOLTAGE
125°C
100
85°C
80
25°C
60
–55°C
40
20
10
15
20
25
30
Vs, (V)
35
40
TOTAL VOLTAGE DROP
6
100
80
125
50
75
100
125
CASE TEMPERATURE, (°C)
0
NORMALIZED Vs QUIESCENT CURRENT, (%)
0
25
TOTAL VOLTAGE DROP, (V)
NORMALIZED Vcc QUIESCENT CURRENT, (%)
NORMALIZED Vs QUIESCENT CURRENT, (%)
101.0
99.0
5
1.0
1.4
0.6
1.8
2.2 2.4
SOURCE TO DRAIN DIODE VOLTAGE
4
101.5
99.5
97.5
100
REVERSE DIODE
5
4
3
102.0
NORMALIZED FREQUENCY, (%)
NORMALIZED FREQUENCY, (%)
30
0
CLOCK FREQUENCY OVER TEMP
100
CONTINUOUS AMPS
FLYBACK CURRENT, Isd (A)
INTERNAL POWER DISSIPATION, (W)
POWER DERATING
40
5
125°C
4
100°C
85°C
3
2
25°C
1
0
–55°C –25°C
0
1
2
3
OUTPUT, I (A)
4
5
SA09U
SA09
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.apexanalog.com for design
tools that help automate pwm filter design and heat sink selection. The "Application Notes" and "Technical Seminar"
sections contain a wealth of information on specific types of applications. Information on package outlines, heat
sinks, mounting hardware and other accessories are located in the "Packages and Accessories" section. Evaluation
Kits are available for most Apex Microtechnology product models, consult the "Evaluation Kit" section for details.
For the most current version of all Apex Microtechnology product data sheets, visit www.apexanalog.com.
CLOCK CIRCUIT AND RAMP GENERATOR
The clock frequency is internally set to a frequency of approximately 1MHz. 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 RAMP pin. An external clock signal can be applied to the CLK IN pin for synchronization purposes. If a clock
frequency lower than 1MHz is chosen an external capacitor must be tied to the RAMP pin. This capacitor, which
parallels an internal capacitor, must be selected so that the ramp oscillates 2.5 volts p-p with the lower peak 1.25
volts above ground.
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 outputs. 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 0.1µF to 0.47µF ceramic capacitor
connected directly to the VCC pin will suffice. NOISE FILTERING
Switching noise can enter the SA09 through the external error amp to +PWM connection. A wise precaution is to low
pass filter this connection. Adjust the pass band of the filter to 10 times the bandwidth required by the application.
Keep the resistor value to 100 ohms or less since this resistor becomes part of the hysteresis circuit on the pwm
comparator.
PCB LAYOUT
The designer needs to appreciate that the SA09 combines in one circuit both high speed high power switching and
low level analog signals. Certain layout rules of thumb must be considered when a circuit board layout is designed
using the SA09:
1. Bypassing of the power supplies is critical. Capacitors must be connected directly to the power supply pins with
very short lead lengths (well under 1 inch). Ceramic chip capacitors are best.
2. Make all ground connections with a star pattern at pin 7.
3. Beware of capacitive coupling between output connections and signal inputs through the parasitic capacitance
between layers in multilayer PCB designs.
4. Do not run small signal traces between the pins of the output section (pins 11-16). 5. Do not allow high currents to flow into the ground plane.
6. Separate switching and analog grounds and connect the two only at pin 7 as part of the star pattern.
INTEGRATOR
The integrator provides the inverted signal for negative feedback and also the open loop gain for the overall application circuit accuracy. Recommended value of CINT is 10 pF for stability. However, poles and zeroes can be added to
the circuit for overall loop stability as required.
SA09U
5
SA09
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 RLIMIT 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 RLIMIT resistors (through the filter network and shutdown divider resistor)
and connect the RLIMIT resistors directly to the GND pin. Do not connect RLIMIT sense resistors to the ground plane.
I SENSE A
R LIMIT
I SENSE A
I SENSE B
1K
I SENSE B
R LIMIT
I LIMIT/SHDN R
FILTER
C FILTER
1K
R LIMIT
1K
SHUTDOWN
SIGNAL
R SHDN
FIGURE A. CURRENT LIMIT WITH
SHUTDOWN VOLTAGE MODE.
SHUTDOWN
SIGNAL
I LIMIT/SHDN R
FILTER
C FILTER
R SHDN
FIGURE B. CURRENT LIMIT WITH
SHUTDOWN CURRENT MODE.
Switching noise spikes will invariably be found at the I SENSE pins. The noise spikes could trip the current limit
threshold which is only 100 mV. RFILTER and CFILTER 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 difficult 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 CFILTER = 0.001uF, RFILTER = 5k .
The required value of RLIMIT in voltage mode may be calculated by: RLIMIT = 0.1 V / ILIMIT
where RLIMIT is the required resistor value, and ILIMIT is the maximum desired current. In current mode the required
value of each RLIMIT is 2 times this value since the sense voltage is divided down by 2 (see Figure B). If RSHDN is used
it will further divide down the sense voltage. The shutdown divider network will also have an effect on the filtering
circuit.
SHUTDOWN
The shutdown circuitry makes use of the internal current limiting circuitry. The two functions may be externally
combined in voltage and current modes as shown below in Figures A and B. The RLIMIT resistors will normally be
very low values and can be considered zero for this application. In Figure A, RSHDN and 1K form a voltage divider for
the shutdown signal. After a suitable noise filter is designed for the current limit, adjust the value of RSHDN to give a
minimum 110 mV of shutdown signal at the I LIMIT/SHDN pin when the shutdown signal is high. Note that CFILTER will
filter both the current limit noise spikes and the shutdown signal. Shutdown and current limit operate on each cycle
of the internal switching rate. As long as the shutdown signal is high the output will be disabled.
PROTECTION CIRCUITS
Circuits monitor the temperature and load on each of the bridge output transistors. On each cycle should any fault
condition be detected all output transistors in the bridge are shut off. Faults protected against are: shorts across
the outputs, shorts to ground, and over temperature conditions. Should any of these faults be detected, the output
transistors will be latched off *. In addition there is a built in dead time during which all the output transistors are off.
The dead time removes the possibility of a momentary conduction path through the upper and lower transistors of
each half bridge during the switching interval. Noise or flyback may be observed at the outputs during this time due
to the high impedance of the outputs in the off state. This will vary with the nature of the load.
* To restart the SA09 remove the fault and recycle VCC and +VS or, alternatively, toggle the I LIMIT/SHDN (pin16)
with a shut down pulse.
6
SA09U
SA09
POWER SUPPLY SEQUENCING
The VCC power supply voltage must be applied prior to the +VS power supply voltage. The output stage devices will
be damaged if the VCC supply is not present when the +VS supply is applied. Always sequence the VCC supply prior
to the +VS supply.
NEED TECHNICAL HELP? CONTACT APEX SUPPORT!
For all Apex Microtechnology product questions and inquiries, call toll free 800-546-2739 in North America.
For inquiries via email, please contact [email protected]
International customers can also request support by contacting their local Apex Microtechnology Sales Representative.
To find the one nearest to you, go to www.apexanalog.com
IMPORTANT NOTICE
Apex Microtechnology, Inc. has made every effort to insure the accuracy of the content contained in this document. However, the information is subject to change
without notice and is provided "AS IS" without warranty of any kind (expressed or implied). Apex Microtechnology reserves the right to make changes without further
notice to any specifications or products mentioned herein to improve reliability. This document is the property of Apex Microtechnology and by furnishing this information, Apex Microtechnology grants no license, expressed or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual
property rights. Apex Microtechnology owns the copyrights associated with the information contained herein and gives consent for copies to be made of the information only for use within your organization with respect to Apex Microtechnology integrated circuits or other products of Apex Microtechnology. This consent does not
extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.
APEX MICROTECHNOLOGY PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN PRODUCTS USED FOR
LIFE SUPPORT, AUTOMOTIVE SAFETY, SECURITY DEVICES, OR OTHER CRITICAL APPLICATIONS. PRODUCTS IN SUCH APPLICATIONS ARE UNDERSTOOD TO BE FULLY AT THE CUSTOMER OR THE CUSTOMER’S RISK.
Apex Microtechnology, Apex and Apex Precision Power are trademarks of Apex Microtechnolgy, Inc. All other corporate names noted herein may be trademarks
of their respective holders.
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SA09U
Copyright © Apex Microtechnology, Inc. 2012
(All Rights Reserved)
OCT 2012
7
SA09U REVD
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