MSMAS2A42400
PP rr oo dd uu cc tt IInnnnoovvaa tt ii oo n FFr roomm
MSA240
Pulse Width Modulation Amplifiers
FEATURES
• LOW COST
• HIGH VOLTAGE - 100 VOLTS
• HIGH OUTPUT CURRENT - 20 AMPS
• 2kW OUTPUT CAPABILITY
• VARIABLE SWITCHING FREQUENCY
APPLICATIONS
• BRUSH MOTOR CONTROL
• MRI
• MAGNETIC BEARINGS
• CLASS D SWITCHMODE AMPLIFIER
58-PIN DIP
PACKAGE STYLE KC
TYPICAL APPLICATION
SINGLE POINT GND @ 26
28
AC
2,18,26
23
58
20
1
SIG DIG PWR
GND RET GND
CLK/2 OUT
IN
DESCRIPTION
BACK
PLATE
R
RAMP
R
RAMP
The MSA240 is a surface mount constructed PWM amplifier
that provides a cost effective solution in many industrial applica-
tions. The MSA240 offers outstanding performance that rivals
many much more expensive hybrid components. The MSA240
is a complete PWM amplifier including an oscillator, comparator,
error amplifier, current limit comparators, 5V reference, a smart
controllerandafullbridgeoutputcircuit.Theswitchingfrequency
is user programmable up to 50 kHz. The MSA240 is built on a
thermally conductive but electrically insulating substrate that
can be mounted to a heatsink.
35-39
49-53
24
22
19
13
A OUT
CLK OUT
R
OSC
R
OSC
PWM AMPLIFIER
+5V REF OUT
+IN
E/A OUT
17
16
B OUT
E/A -IN
15 E/A +IN
Is B
54-57
Is A
40-43
CONTROL
SIGNAL
2.5V
A1
EQUIVALENT CIRCUIT DIAGRAM
Rs A
Rs B
VCC
29
5V REF
19
2.5V
OUT
5V
SIGNAL
GND
REF
26
18
2
30-34
44-48
TORQUE MOTOR CONTROL
SIGNAL
GND
+Vs
+Vs
SIGNAL
GND
With the addition of a few external components the MSA240
becomes a motor torque controller. In the MSA240 the source
terminal of each low side MOSFET driver is brought out for
current sensing via RSA and RSB.A1 is a differential amplifier
that amplifies the difference in currents of the two half bridges.
This signal is fed into the internal error amplifier that mixes the
current signal and the control signal. The result is an input
signal to the MSA240 that controls the torque on the motor.
200mV
DIGITAL
RETURN
23
7
+
1K
-
ILIM
B
Q1
Q3
Q2
.01F
1K
+
-
35-39
ILIM A/SHDN
ROSC
10
22
A OUT
SMART
CONTROLLER
2.68K
.01F
D1
OSC
2200pF
49-53
CLK OUT
24
17
16
15
13
1
B OUT
EXTERNAL CONNECTIONS
E/A OUT
E/A -IN
E/A +IN
+IN
D2
Q4
54-57
-
I SENSE B
I SENSE A
+
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
R2
R3
40-43
RRAMP
+
-
SINGLE
5.36K
POINT
GND
RRAMP IN
VIEW FROM
COMPONENT SIDE
ROSC
2200pF
CLK/2 OUT
CLK IN
20
21
28
27
58
CLK/2
C1
C2
C3
+
AC BACK
PLATE
BACK PLATE
1F
58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29
APEX TP
PWR
GND
I
B
B OUT
+Vs
I
A
A OUT
+Vs
VCC
SENSE
SENSE
PWR
GND
NOTES: C2 IS ELECTROLYTIC ≥10UF PER AMP OUTPUT CURRENT
C1,3 HIGH QUALITY CERAMIC ≥1.0UF
ALL +Vs MUST BE TIED TOGETHER
ALL SIG GND PINS MUST BE TIED TOGETHER
SINGLE POINT GROUND @ PIN 26
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
MAY 2009
1
APEX − MSA240UREVD
MSA240U
http://www.cirrus.com