CIRRUS SA56_07

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M I C R O T E C H N O L O G Y
FEATURES
• DELIVERS UP TO 5A CONTINUOUS OUTPUT
• OPERATES AT SUPPLY VOLTAGES UP TO 60V
• NO “SHOOT-THROUGH” CURRENT
• THERMAL SHUTDOWN (OUTPUTS OFF) AT 160°C
• SHORTED LOAD PROTECTION (to VS or PGND or SHORTED
LOAD)
• NO BOOTSTRAP CAPACITORS REQUIRED
• PROGRAMMABLE ONBOARD PWM
APPLICATIONS
• DC BRUSH-TYPE MOTOR DRIVES
• POSITION AND VELOCITY SERVOMECHANISMS
• FACTORY AUTOMATION ROBOTS
• NUMERICALLY CONTROLLED MACHINERY
• COMPUTER PRINTERS AND PLOTTERS
FIGURE 1. BLOCK DIAGRAM
23 Pin SIP
Package Style EX
DESCRIPTION
The SA56 is a 5-ampere PWM Amplifier designed for motion
control applications. The device is built using a multi-technology
process that combines bipolar and CMOS control circuitry with
DMOS power devices in a single monolithic structure. Ideal
for driving DC and stepper motors, the SA56 accommodates
peak output currents up to 10 amperes. An innovative circuit
that facilitates low-loss sensing of the output current has been
implemented. An on-board PWM oscillator and comparator
are used to convert an analog signal into PWM direction of
rotation and magnitude for motor control applications. TTL or
CMOS digital inputs allow direct external control in 2-quadrant
or 4-quadrant modes.
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APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL [email protected]
SA56
ABSOLUTE MAXIMUM RATINGS
ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONS
SUPPLY VOLTAGE, VDD
SUPPLY VOLTAGE, VS
PEAK OUTPUT CURRENT (100mS)
CONTINUOUS OUTPUT CURRENT
POWER DISSIPATION
POWER DISSIPATION (TA = 25°C, Free Air) JUNCTION TEMPERATURE, TJ(MAX)
ESD SUSCEPTIBILITY (Logic Pins Only)
STORAGE TEMPERATURE, TSTG
LEAD TEMPERATURE (Soldering, 10 sec.)
JUNCTION TEMPERATURE, TJ
5.5V
60V
10A
5A
125W
10W
150°C
1500V
–40°C to +150°C
300°C
–40°C to +150°C
SPECIFICATIONS
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
VS
12
60
VDD
4.5
5.5
SWITCH ON RESISTANCE, RDS(ON)
Output Current = 5A
0.23
0.6
N-Channel
SWITCH ON RESISTANCE, RDS(ON)
Output Current = 5A
0.27
0.6
P-Channel
CLAMP DIODE FORWARD DROP, VCLAMP
Clamp Current = 5A
1.43
LOGIC LOW INPUT VOLTAGE, VIL
-0.5
0.8
LOGIC LOW INPUT CURRENT, IIL
VIN = –0.1V
-10
+10
LOGIC HIGH INPUT VOLTAGE, VIH
2
VDD
µA
V
LOGIC HIGH INPUT CURRENT, IIH
CURRENT SENSE OUTPUT
CURRENT SENSE LINEARITY ERROR
VIN = 5.5V
-10
IOUT = 1A
180
240
IOUT = 5A
.79
1.0
1A ≤ IOUT ≤ 5A
±1
100 mA ≤ IOUT ≤ 5A
5A ≤ IOUT ≤ 10A (Peak Currents only)
µA
µA
mA
%
%
%
SHUTDOWN TEMPERATURE, TJSD
QUIESCENT SUPPLY CURRENT, IS
QUIESCENT SUPPLY CURRENT, IDD
OUTPUT TURN-ON DELAY TIME, tDon
OUTPUT TURN-ON SWITCHING TIME, ton
OUTPUT TURN-OFF DELAY TIMES, tDoff
OUTPUT TURN-OFF SWITCHING TIME, toff
MINIMUM INPUT PULSE WIDTH, tp
(DIGITAL MODE)
Outputs Turn OFF
No Load, FSW = 100kHz 50% DUC
No Load, FSW = 100kHz 50% DUC
No Load No Load
No Load No Load No Load
160
26
50
6
15
200
41
272
46
140
REFERENCE VOLTAGE
IREF = 1mA
2.5
Vref OUTPUT CURRENT (Vref 2.5V), IREF
Source Only, No current sink capability
2.3
ANALOG INPUT RANGE FOR Load Current = 400µA
1
FULL MODULATION
HIGH CURRENT SHUTDOWN RESPONSE Output shorted
250
(No bypass capacitor at SCin pin)
10
300
1.32
±5
±8
±8
V
V
Ω
Ω
V
V
°C
mA
mA
ns
ns
ns
ns
ns
2.7
V
1
mA
4
V
800
ns
THERMAL
RESISTANCE, Junction to Case
Full Temperature Range
1
RESISTANCE, Junction to Air
Full Temperature Range
12.21
TEMPERATURE RANGE, Case
-40
125
°C/W
°C/W
°C
NOTE: These specifications apply for VS = 50V and VDD = 5V at 25°C, unless otherwise specified.
APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739
SA56
TYPICAL
PERFORMANCE GRAPHS
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APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL [email protected]
SA56
TYPICAL
PERFORMANCE GRAPHS
RDSON = 125°C
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RDSON = 0°C
RDSON = 50°C
0.15
RDSON = 85°C
0.1
0.2
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APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739
OPERATING
CONSIDERATIONS
SA56
GENERAL
Please read "SA56 Design Ideas" that covers the various
SA56 applications in considerable detail. Also see Application
Note 1 "General Operating Considerations" which covers stability, power supplies, heat sinking, mounting, and specification
interpretation. Visit www.apexmicrotech.com for design tools
that help automate tasks such as calculations for stability,
internal power dissipation, current limit, heat sink selection,
Apex's complete Application Notes library, Technical Seminar
Workbook and Evaluation Kits.
GROUND PINS
The two SIGGND pins, 9 & 10, are for input signal grounds.
Pins 1 and 23, PGND, are power grounds. The PGND & SIGGND
pins are connected at one point inside the IC. It is also recommended the user connect both pins at a single point on the board
in a way that no current flows through that connection.
POWER SUPPLY BYPASSING
Bypass capacitors to power supply terminals VS and VDD must
be connected physically close to the pins to prevent erratic,
low-efficiency operation and excessive ringing at the outputs.
Electrolytic capacitors, at least 10 μF per output ampere are
required for suppressing VS to PGND noise. High quality ceramic
capacitors (X7R) 1 μF or greater should also be used. Only capacitors rated for switching applications should be considered.
The bypass capacitors must be located as close to the power
supply pins as possible. Due to the very fast switching times
of the outputs, the inductance of 1 inch of circuit trace could
cause noticeable degradation in performance. The bypassing
requirements of VDD are less stringent, but still necessary. A
0.1 μF to 0.47 μF capacitor connected directly between the
VDD and SIGGND pins will suffice.
PIN DESCRIPTIONS
Pin # Name
1,23 PGND
2,3 Bout
4,5, VS
19,20
6
SC
7
TLIM
Description
Power high current ground return path of the
motor.
Half bridge output B
High voltage supply
The short-circuit protection circuits will sense
a direct short from either output (AOUT or
BOUT) to PGND or VS – as well as across the
load. If the high-current protection circuit
engages it will place all four MOSFETs in the
tristate state (high-impedance output). The
SC output, pin 6, will go HIGH though not
latch, thereby denoting that this protection
feature has been triggered.
Temperature limit, CMOS. This pin can be
used as a flag for an over-temperature condition. Under normal operation this pin will
be logic low. When a junction temperature
exceeds approximately 160°C this pin will
change to logic high and the output will be
latched off. Grounding this pin disables over
temperature protection. This pin should be
left open if over temperature protection is
desired but the flag is not used.
Current Sense output and programmable
8
ISEN
current limit. A current proportional to the
output current is sourced by this pin. Typically this pin is connected to a resistor for
programmable current limit or transconductance operation.
9,10 SIGGND Ground connection for all internal digital and
low-current analog circuitry.
11
FAULT This pin latches high whenever the four
MOSFETs have been placed in the tristate
condition which occurs when either the
high-current or the thermal protection has
engaged.
An external timing capacitor is connected to
12
CPWM
this pin to set the frequency of the internal
oscillator and ramp generator for analog
control mode. The capacitor value (pF)
= 4.05x107/FSW, where FSW = the desired
switching frequency. This pin is grounded
for digital control mode.
5V supply for input logic and low voltage
13,14 VDD
analog circuitry.
Reference voltage. Can be used at low cur15
VREF
rent for biasing analog loop circuits.
16
DIR
Direction of rotation control; In 2 quadrant,
digital control, determines the active output
FETs. This pin should be grounded in analog
control mode.
17
PWM
CMOS/TTL input for digital PWM control, or
1-4V analog input for duty cycle control in
analog control mode.
18
DISABLE Following a fault, pulling the DISABLE pin
HIGH and then LOW will reset a latched
fault condition. (When pulled HIGH, all four
output MOSFETs are disabled. A logic LOW
on this pin allows the four output FETs to
function normally.) When the DISABLE and
FAULT pins are tied to a microcontroller, the
FAULT pin will generate an interrupt in the
microcontroller, so that the interrupt, can in
turn, generate a pulse on the DISABLE pin.
When a fault occurs, the SA56 fault circuitry
will be reset.
Half bridge output A
21,22 AOUT
APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL [email protected]
SA56
OPERATING
CONSIDERATIONS
MODES OF OPERATION
The following chart shows the 3 modes of operation.
Mode
CPWM
pin 12
PWM
pin 17
DIR
pin 16
AOUT
pins 21, 23
Bout
pins 2, 3
2 Quadrant – Analog Mode
Connect capacitor to set
frequency
Analog control
voltage
(1 – 4V)
Low (SIGGND)
Control voltage
greater than VREF:
(AOUT – BOUT)< 0
average
voltage
Control voltage
greater than VREF:
(BOUT – AOUT)> 0
average
voltage
2 Quadrant – Digital Mode
SIGGND
Modulation In
High (VDD)
High (VS)
PWM
SIGGND
Modulation In
Low (SIGGND)
PWM
High (VS)
SIGGND
High (VDD)
Modulated In
DIR
DIR
4 Quadrant – Digital Mode
4-QUADRANT - ANALOG MODE
2-QUADRANT - DIGITAL MODE
The SA56 can operate in 4-quadrant mode with analog or
digital inputs. In the analog mode, the capacitor from CPWM to
SIGGND sets the frequency of an internal triangular ramp signal. See Figure 2. An analog voltage applied to the PWM pin
is compared to a 2.5 volt reference within the SA56 thereby
governing the duty cycle of the output. Note that the analog
pin DIR pin 16 is connected to signal ground (SIGGND).
Two-quadrant operation of the FETs is realized by driving
PWM pin 17 of the SA56 with a digital PWM signal supplied
by a microcontroller or DSP, as depicted in Figure 3. When
using a digital modulation signal, connect the CPWM pin to
SIGGND to disable the internal oscillator and its companion
ramp generator.
A digital PWM signal applied to the PWM pin controls the
output duty cycle at one output pin while the other output pin is
held "HIGH". The input at the DIR pin (VDD or SIGGND) governs
the output behavior. If DIR is a logic HIGH, the AOUT output
will be held high and the BOUT output will be switched as the
complement of the PWM input signal. The average output at
AOUT will always be greater than at BOUT. Whereas if DIR is a
logic LOW, the BOUT output will be held "HIGH" and the AOUT
output will be switched.
Operating in two-quadrant mode reduces switching noise
and power dissipation, but limits the ability to control the motor
at very low speed.
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Two and 4-quadrant operation are possible with the SA56
when driven with a digital PWM signal from a microcontroller or
DSP. When using a digital modulation signal, tie the CPWM pin
to SIGGND to disable the internal oscillator and ramp generator.
When operating in the digital mode, pulse widths should be no
less than 100 ns and the switching frequency should remain
less than 500 kHz. This will allow enough time for the output
MOSFETs to reach their full on and off states before receiving
a command to reverse state.
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APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739
SA56
OPERATING
CONSIDERATIONS
4 QUADRANT DIGITAL MODE
During four-quadrant operation a single digital PWM input
includes magnitude and direction information. The digital PWM
input signal is applied to the DIR pin, as shown in Figure 4,
and the PWM pin is tied HIGH to VDD. Both pairs of output
MOSFETs will switch in a locked, complementary fashion.
With a 50% duty cycle the average voltage of outputs
AOUT and BOUT will be the same, which is half of VS so that the
average differential voltage over each period applied to the
load will therefore be zero.
Four-quadrant operation allows for smooth transitions
through zero current for low-speed applications. However,
power dissipation is slightly higher than in two-quadrant operation since all four output MOSFETs must switch every cycle.
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BRAKING – DIGITAL MODE
Under digital control, the SA56 can rapidly decelerate the
motor by shunting the winding currents through the output
MOSFETs. Logic LOW on the PWM input both A and B outputs high. The motor winding current circulates through the on
resistance of the MOSFETs quickly slowing the motor.
The winding current can be monitored with the ISEN pin
during the braking of the motor. However, the current during
braking circulates in the normal forward direction through one
output MOSFET and is in the reverse in the other MOSFET.
The current sense feature can measure only forward currents.
The logic input on the DIR pin dictates which output MOSFET
is used for sensing the forward current during braking.
PROTECTION CIRCUITS
The most severe condition for any power device is a direct,
hard-wired ("screwdriver") short from an output to ground.
While the short-circuit protection will latch the output MOSFETs
within 500 ns (typical), the die and package may be required to
dissipate up to 500 Watts of power until the protection circuits
are activated.
This energy can be destructive, particularly at higher operating voltages, so sound thermal design is critical if fault tolerance
is to be established in the design. The VS and PGND pins may
become very hot during this period of high current.
Thermal and short-circuit protection are included in the
SA56 to prevent damage in the event that faults occur as
described below:
Short-circuit protection – The short-circuit protection circuits
will sense a direct short from either output (AOUT or BOUT) to
PGND or VS – as well as across the load. If the high-current
protection circuit engages, it will place all four MOSFETs in
the tristate state (high-impedance output). The SC output, pin
6, will go HIGH though not latch, thereby denoting that this
protection feature has been triggered.
Over-current protection – When the current on the high side
goes above 10 amperes peak, the over-current circuit tristates
so that the four MOSFETs go into a latched fault condition.
Thermal protection – The thermal protection circuits will engage if the temperature of any of the four MOSFETs reaches
approximately 160°C. If this occurs, the FAULT output pin will
go HIGH. If the thermal protection circuit engages, it will place
all four MOSFETs in the tristate state (high-impedance output).
The TLIM output which is normally LOW will go HIGH, though
not latch, thereby denoting which of the protection features
has been triggered.
PROGRAMMABLE CURRENT LIMIT
The ISEN pin sources a current proportional to the forward
output current of the active P channel output MOSFET. The
proportionality is approximately 200 microamperes per ampere
of output current. Note that the ISEN output is blocked during
the switching transitions when current spikes are likely to be
significant.
To create a programmable current limit, connect a resistor
from ISEN to SIGGND. If the voltage across this resistor exceeds
an internally-generated 2.75V threshold, all four output MOSFETs will be turned off for the remainder of the switching cycle.
A 2.7k-Ohm resistor will set the current limit at approximately
5 amperes.
The ISEN output can also be used for maintaining a current
control loop in torque motor applications.
CURRENT SENSE LINEARITY CALCULATION
The current sense linearity is specified in the table on page
2 and is calculated using the method described below:
a) Define a straight line (y = mx + b) joining the two end data
points where, m is the slope and b is the offset or zero
crossover. Calculate the slope m and offset c using the
extreme data points. Assume Isense in the y axis and Iload
in the x axis.
b) Calculate linear ISEN (or ideal Isense value, ISIDEAL) using
the straight line equation derived in step (a) for the Iload
data points.
c) Determine deviation from linear ISEN (step (b) and actual
measured Isense value (ISACTUAL) as shown below:
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APEX
MICROTECHNOLOGY
• TELEPHONE
(520)
690-8600
• FAX (520)
888-3329
ORDERS (520)
690-8601
• EMAILare
[email protected]
This data
sheet has been carefullyCORPORATION
checked and is believed
to be reliable,
however,
no responsibility
is assumed
for possible• inaccuracies
or omissions.
All specifications
subject to change without notice.
SA56U REV A FEBRUARY 2007 © 2007 Apex Microtechnology Corp.