CIRRUS MSA240

MSA240
MSA240
P r o dMSA240
u c t IInnnnoovvaa t i o n FFr roomm
Pulse Width Modulation Amplifiers
FEATURES
• LOW COST
• HIGH VOLTAGE - 100 VOLTS
• HIGH OUTPUT CURRENT - 20 AMPS
• 2kW OUTPUT CAPABILITY
• VARIABLE SWITCHING FREQUENCY
APPLICATIONS
58-pin DIP
PACKAGE STYLE KC
• BRUSH MOTOR CONTROL
• MRI
• MAGNETIC BEARINGS
• CLASS D SWITCHMODE AMPLIFIER
TYPICAL APPLICATION
SINGLE POINT GND @ 26
DESCRIPTION
20
RRAMP
The MSA240 is a surface mount constructed PWM amplifier
that provides a cost effective solution in many industrial applications. 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
controller and a full bridge output circuit.The switching frequency
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.
1
RRAMP IN
24
ROSC
22
19
A OUT
CLK OUT
17 E/A OUT
B OUT
CONTROL
SIGNAL
2.5V
CLK/2 OUT
R2
5.36K
1
21
AC BACK
PLATE
28
APEX TP
27
PWR
GND
58
MSA240U
40-43
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19
NC
1
20 21 22 23 24 25 26 27 28
RRAMP
I SENSE A
-
VIEW FROM
COMPONENT SIDE
2200pF
20
CLK IN
R3
+
SIG GND
APEX TP
AC BACK
PLATE
13
CLK OUT
+IN
I SENSE B
DIG RTN
+
54-57
CLK/2 OUT
15
Q4
CLK IN
ROSC
E/A +IN
EXTERNAL CONNECTIONS
B OUT
D2
+5V OUT
-
49-53
EA OUT
16
Q3
SIG GND
E/A -IN
OSC
D1
NC
17
.01F
EA -IN
E/A OUT
2200pF
A OUT
SMART
CONTROLLER
EA +IN
24
35-39
-
+IN
CLK OUT
Q2
NC
22
Q1
NC
2.68K
+
NC
10
+
ILIM A/SHDN
1K
+Vs
ILIM B
7
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.
44-48
200mV
DIGITAL
RETURN
1K
NC
SIGNAL
GND
+Vs
NC
2
TORQUE MOTOR CONTROL
30-34
NC
SIGNAL
GND
NC
18
ROSC
RRAMP IN
Rs A
5V
REF
26
.01F
ILIM A/SHDN
40-43
Rs B
23
ILIM B
Is A
Is B
54-57
2.5V
A1
NC
SIGNAL
GND
49-53
16 E/A -IN
15 E/A +IN
RRAMP IN
29
19
PWM AMPLIFIER
+5V REF OUT
13 +IN
SIG GND
VCC
35-39
ROSC
EQUIVALENT CIRCUIT DIAGRAM
5V REF
OUT
58
2,18,26
28
23
SIG DIG PWR
AC
GND RET GND
BACK
PLATE
CLK/2 OUT
CLK/2
C1
SINGLE
POINT
GND
ROSC
C2
+
C3
BACK PLATE
1F
http://www.cirrus.com
58
PWR
GND
57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36
ISENSE B
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
B OUT
+Vs
ISENSE A
A OUT
35 34 33 32 31
+Vs
30 29
VCC
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
MAY 20091
APEX − MSA240UREVD
MSA240
P r o d u c t I n n o v a t i o nF r o m
ABSOLUTE MAXIMUM RATINGS
SUPPLY VOLTAGE, VS
SUPPLY VOLTAGE, VCC
OUTPUT CURRENT, peak
POWER DISSIPATION, internal, DC
SIGNAL INPUT VOLTAGES
TEMPERATURE, pin solder, 10s
TEMPERATURE, junction2
TEMPERATURE RANGE, storage
OPERATING TEMPERATURE, case
100V
16V
30A, within SOA
250W3
5.4V
225°C.
175°C.
-40° to 105°C.
-40° to 85°C.
SPECIFICATIONS
PARAMETER
TEST CONDITIONS1
ERROR AMPLIFIER
OFFSET VOLTAGE
BIAS CURRENT
OFFSET CURRENT
COMMON MODE VOLTAGE RANGE
SLEW RATE
OPEN LOOP GAIN
UNITY GAIN BANDWIDTH
Full temperature range
Full temperature range
Full temperature range
Full temperature range
Full temperature range
RL = 2KΩ
CLOCK
LOW LEVEL OUTPUT VOLTAGE
HIGH LEVEL OUTPUT VOLTAGE
RISE TIME
FALL TIME
BIAS CURRENT, pin 22
Full temperature range
Full temperature range
OUTPUT MOSFET BODY DIODE
CONTINUOUS CURRENT
FORWARD VOLTAGE
REVERSE RECOVERY
I = 16A
IF = 16A
2
3.
4.
UNITS
1
96
1
9
500
150
4
mV
nA
nA
V
V/µS
dB
MHz
.2
0.6
V
V
nS
nS
µA
5.15
2
V
mA
155
20
30
mΩ
A
A
20
A
V
nS
100
16
28
18
10
V
V
mA
mA
mA
1.2
14
85
°C/W
°C/W
°C/W
0
4.8
4.85
100mS
NOTES: 1.
2.
MAX
Full temperature range
OUTPUT
TOTAL RON, both MOSFETs4
CURRENT, continuous
CURRENT, peak
THERMAL
RESISTANCE, DC, junction to case
RESISTANCE, junction to air
TEMPERATURE RANGE, case
TYP
7
7
5V REFERENCE OUTPUT
VOLTAGE
LOAD CURRENT
POWER SUPPLY
VOLTAGE, VS
VOLTAGE, VCC
CURRENT, VS, quiescent
CURRENT, VCC, quiescent
CURRENT, VCC, shutdown
MIN
IO = 20A , TJ = 85°C
1.3
250
3
14
22kHz switching
22kHz switching
Full temperature range
Full temperature range
-40
60
15
4
Unless otherwise noted: TC=25°C, VCC = 15V, VS = 60V
Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation to achieve high MTBF.
Each of the two output transistors on at any one time can dissipate 125W.
Maximum specification guaranteed but not tested.
MSA240U
MSA240
NORMALIZED FREQUENCY, (%)
100
75
50
25
20
40
60
80
100
CASE TEMPERATURE, (C)
REVERSE DIODE
=2
98
FREQUENCY = 44KHz
97
1M
100K
10K
CLOCK LOAD RESISTANCE, ()
T
CONTINUOUS OUTPUT
4
3
TC
2
=2
1
4
8
12
16
OUTPUT CURRENT, (A)
20
DUTY CYCLE, (%)
CONTINUOUS AMPS
A OUT
60
40
20
5
B OUT
102
25
50
75
CASE TEMPERATURE, (C)
0
1.5
100
VCC QUIESCENT CURRENT
101
100
99
98
NORMAL or SHUTDOWN
OPERATION
97
-40 -20 0 20 40 60 80 100
CASE TEMPERATURE, (C)
MSA240U
VCC QUIESCENT CURRENT
2.0
2.5
3.0
3.5
ANALOG INPUT, (V)
VS QUIESCENT CURRENT, (mA)
NORMALIZED QUIESCENT CURRENT, (%)
0
0
99.2
-40 -20
0 20 40 60 80 100
CASE TEMPERATURE, (C)
5C
TC
80
10
99.4
85
DUTY CYCLE VS. ANALOG INPUT
15
99.6
C
=
100
20
99.8
TOTAL VOLTAGE DROP
0
0
0
0.4
0.6
0.8
1.0
1.2
SOURCE TO DRAIN DIODE VOLTAGE
25
99
VCC QUIESCENT CURRENT, (mA)
=1
J
4
5C
25
C
12
8
100.0
5
16
T
FLYBACK CURRENT, ISD (A)
20
CLOCK FREQUENCY OVER TEMP.
100.2
5
VS QUIESCENT CURRENT
4
3
2
1
0
F = 22kHz,
50% DUTY CYCLE
20
40
60
VS, (V)
80
100
24
20
16
12
8
50% DUTY CYCLE
4
0
10
20
30
40
50
SWITCHING FREQUENCY, F (kHz)
VS QUIESCENT CURRENT vs. FREQUENCY
VS QUIESCENT CURRENT, IQ (mA)
0
TOTAL VOLTAGE DROP, (V)
0
CLOCK LOADING
100
NORMALIZED FREQUENCY, (%)
POWER DERATING
125
J
INTERNAL POWER DISSIPATION, (W)
P r o d u c t I n n o v a t i o nF r o m
8
6
4
2
VS = 60V,
50% DUTY CYCLE
0
0
10
20
30
40
50
SWITCHING FREQUENCY, F (kHz)
3
MSA240
P r o d u c t I n n o v a t i o nF r o m
GENERAL
OSCILLATOR
20
CLK/2 OUT
CLK OUT
21
CLK IN
24
ROSC
22
RRAMP
1
RRAMP IN
ROSC
PWM AMPLIFIER
SHUTDOWN
The MSA240 output stage can be turned off with a shutdown
command voltage applied to Pin 10 as shown in Figure 2. The
shutdown signal is OR’ed with the current limit signal and
simply overrides it. As long as the shutdown signal remains
high the output will be off.
CURRENT SENSING
The low side drive transistors of the MSA240 are brought
out for sensing the current in each half bridge. A resistor from
each sense line to PWR GND (pin 58) develops the current
sense voltage. Choose R and C such that the time constant
is equal to 10 periods of the selected switching frequency. The
internal current limit comparators trip at 200mV. Therefore,
current limit occurs at I = 0.2/RSENSE for each half bridge. See
10
7
R
Isense B
Isense A
IlimB
PWR
GND
58
PWM AMPLIFIER
40-43
54-57
Rs A
Rs B
C
9R
The MSA240 includes a user frequency programmable
oscillator. The oscillator determines the switching frequency
of the amplifier. The switching frequency of the amplifier is 1/2
the oscillator frequency. Two resistor values must be chosen
to properly program the switching frequency of the amplifier.
One resistor, ROSC, sets the oscillator frequency. The other
resistor, RRAMP, sets the internal ramp amplitude. In all cases
the ramp voltage will oscillate between 1.5V and 3.5V. See
Figure 1. If an external oscillator is applied use the equations
to calculate RRAMP .
To program the oscillator, ROSC is given by:
ROSC = (1.32X108 / F) - 2680
where F is the desired switching frequency and:
RRAMP = 2 X ROSC
Use 1% resistors with 100ppm drift (RN55C type resistors,
for example). Maximum switching frequency is 50kHz.
Example:
If the desired switching frequency is 22kHz then ROSC = 3.32K
and RRAMP = 6.64K. Choose the closest standard 1% values:
ROSC = 3.32K and RRAMP = 6.65K.
FIGURE 1. EXTERNAL OSCILLATOR CONNECTIONS
4
Figure 2. Accurate milliohm power resistors are required and
there are several sources for these listed in the Accessories
Vendors section of the Databook.
FIGURE 2. CURRENT LIMIT WITH OPTIONAL SHUTDOWN
IlimA/SHDN
Please read Application Note 30 “PWM Basics”. Refer also
to Application Note 1 “General Operating Considerations” for
helpful information regarding power supplies, heat sinking,
mounting, SOA interpretation, and specification interpretation.
Visit www.Cirrus.com for design tools that help automate tasks
such as calculations for stability, internal power dissipation,
current limit, heat sink selection, Apex Precision Power’s complete Application Notes library, Technical Seminar Workbook
and Evaluation Kits.
R
C
5V SHDN
SIGNAL
POWER SUPPLY BYPASSING
Bypass capacitors to power supply terminals +VS must be
connected physically close to the pins to prevent local parasitic
oscillation and overshoot. All +VS pins must be connected
together. Place an electrolytic capacitor of at least 10µF per
output amp required midpoint between these sets of pins. In
addition place a ceramic capacitor 1µF or greater directly at
each set of pins for high frequency bypassing. VCC is bypassed
internally.
GROUNDING AND PCB LAYOUT
Switching amplifiers combine millivolt level analog signals
and large amplitude switching voltages and currents with fast
rise times. As such grounding is crucial. Use a single point
ground at SIG GND (pin 26). Connect signal ground pins 2 and
18 directly to the single point ground on pin 26. Connect the
digital return pin 23 directly to pin 26 as well. Connect PWR
GND pin 58 also to pin 26. Connect AC BACKPLATE pin 28
also to the single point ground at pin 26. Connect the ground
terminal of the VCC supply directly to pin 26 as well. Make sure
no current from the load return to PWR GND flows in the analog
signal ground. Make sure that the power portion of the PCB
layout does not pass over low-level analog signal traces on
the opposite side of the PCB. Capacitive coupling through the
PCB may inject switching voltages into the analog signal path.
Further, make sure that the power side of the PCB layout does
not come close to the analog signal side. Fast rising output
signal can couple through the trace-to-trace capacitance on
the same side of the PCB.
DETERMINING THE OUTPUT STATE
The input signal is applied to +IN (Pin 13) and varies from
1.5 to 3.5 volts, zero to full scale. As +IN varies from 1.5 to 2.5
volts the A output "high" duty cycle (relative to ground) is greater
than the B output "high" duty cycle. The reverse occurs as the
input signal varies from 2.5 to 3.5 volts. When +IN = 2.5 volts
the duty cycles of both A and B outputs are 50%. Consequently,
when the input voltage is 1.5V the A output is close to 100%
duty cycle and the B output is close to 0% duty cycle. The
reverse occurs with an input voltage of 3.5V. The output duty
cycle extremes vary somewhat with switching frequency and
are internally limited to approximately 5% to 95% at 10kHz and
7% to 93% at 50kHz.
MSA240U
P r o d u c t I n n o v a t i o nF r o m
MSA240
Contacting Cirrus Logic Support
For all Apex Precision Power 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 Cirrus Logic Sales Representative.
To find the one nearest to you, go to www.cirrus.com
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MSA240U
5