A3936: DMOS Three-Phase PWM Motor Driver

A3936
DMOS Three-Phase PWM Motor Driver
Features and Benefits
Description
▪ ±3 A, 50 V continuous output rating
▪ Low rDS(on) outputs (typically 500 mΩ source,
315 mΩ sink)
▪ Configurable mixed-, fast- and slow-current-decay modes
▪ Synchronous rectification for low power dissipation
▪ Internal UVLO and thermal shutdown circuitry
▪ Crossover-current protection
▪ Tachometer output for external speed control loop
Designed for pulse-width-modulated (PWM) current control
of three-phase brushless DC motors, the A3936 is capable of
peak output currents to ±3 A and operating voltages to 50 V.
Internal fixed off-time PWM current-control timing circuitry
can be configured to operate in slow-, fast- and mixed-decay
modes.
Internal synchronous rectification control circuitry is provided
to improve power dissipation during PWM operation.
Internal circuit protection includes thermal shutdown with
hysteresis, and crossover current protection. Special power-up
sequencing is not required.
Package: 44-pin PLCC (suffix ED)
The A3936 is supplied in a 44-pin plastic PLCC with internally
fused leads (three on each side) for enhanced heat dissipation.
These leads are at ground potential and need no electrical
isolation. This device is lead (Pb) free version, with 100%
matte tin leadframe plating.
Not to scale
Typical Application
VREG
CP1
OSC
Regulator
VDD
TACH
HBIAS
SLEEP
DIR
EXT MODE
BRAKE
SR
Osc
TSD
UVLO [VDD
VREG VCP]
Charge Pump
3X Half Bridge
VBB1
OUTA
OUTB
M
OUTC
Control Logic
and Gate Drive
Fixed Off-Time
PWM Current Ctrl.
Blanking Time
Crossover
Current Protection
BLANK
Fast, Slow, and
Mixed Decay
PFD1
Sync. Rect.
LSS1
Zero Current Detect
Current Sense
GND
LSS2
SENSE
HA–
HB–
HC–
HA+
HB+
HC+
PFD2
4X
GND
VCP
VBB2
ENABLE
A3936-DS, Rev. 8
CP2
GND
VDD
A3936
DMOS Three-Phase PWM Motor Driver
Selection Guide
Part Number
Packing
Package
A3936SEDTR-T*
450 pieces per reel
44-pin PLCC with internally fused leads
*Variant is in production but has been determined to be LAST TIME BUY. This classification indicates that the variant is obsolete and notice has been given. Sale of the variant is currently restricted to existing customer applications. The variant should not be purchased for new design applications because of obsolescence in the near future.
Samples are no longer available. Status date change November 2, 2009. Deadline for receipt of LAST TIME BUY
orders is April 30, 2010.
Absolute Maximum Ratings
Rating
Units
Load Supply Voltage
Characteristic
VBB
50
V
Logic Supply Voltage
VDD
7.0
V
VIN
tw > 30 ns
–0.3 to VDD + 0.3
V
Logic Input Votage Range
tw < 30 ns
–1.0 to VDD + 1
V
0.5
V
VDD
V
±3
A
Sense Voltage
Reference Voltage
Output Current
Symbol
Notes
VSENSE
VREF
IOUT
Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any
set of conditions, do not exceed the specified current rating or a junction temperature of 150°C.
Operating Ambient Temperature
TA
–20 to 85
ºC
Maximum Junction Temperature
TJ(max)
150
ºC
Tstg
–55 to 150
ºC
Storage Temperature
Range S
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A3936
DMOS Three-Phase PWM Motor Driver
TACH
B ANDG AP
HBIAS
VREG
HA+
HA-
HALL
CP1
CP2
R E G U LA T O R
C HAR G E P UMP
VCP
.22uf/50V
VDD
.22uf/100V
VREG
.22uf/50V
Functional Block Diagram
OVERVOLTAGE
UNDERVOLTAGE
AND FAULT
DETECT
VBB1
VCP
VBB2
Comm
Log ic
HB+
HB-
HALL
OUTA
HC+
Control
Log ic
HC-
HALL
GATE
DRIVE
OUTB
SLEEP
OUTC
DIR
EXTMODE
LSS2
BRAKE
LSS1
SR
SENSE
-
ZERO
CURRENT
DETECT
RS
+
GND
.1uF
ENABLE
VDD
OSC
-
PFD1
PWM
TIMER
CURRENT
SENSE
+
BLANK
BUFFER/
DIVIDER
REF
PFD2
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A3936
DMOS Three-Phase PWM Motor Driver
ELECTRICAL CHARACTERISTICS at TJ = +25°C, VBB = 50 V, VDD = 5.0 V, fPWM < 50KHz (unless noted otherwise)
Limits
Characteristics
Sym bol
Test Conditions
M in.
Typ.
M ax.
Units
Operating
9
–
50
V
During Sleep Mode
0
50
V
VOUT = VBB
–
<1.0
20
μA
VOUT = 0 V
–
<–1.0
-20
MA
Source Driver, IOUT = -3A
–
.55
7
Sink Driver, IOUT = 3A
–
.35
7
Source Diode, IF = -3A
–
–
1.4
V
Sink Diode, IF = 3A
–
–
1.3
V
fPWM < 50 kHz
–
4
7
mA
Charge Pump On, Outputs Disabled
–
2
5
mA
Sleep Mode
–
–
20
uA
fPWM < 50 kHz
–
10
mA
Outputs Off
–
8
mA
100
MA
Output Drivers
Load Supply Voltage Range
Output Leakage Current
Output On Resistance
Body Diode Forward Voltage
Motor Supply Current
Logic Supply Current
VBB
IDSS
RDSON
VF
IBB
IDD
Sleep Mode (Inputs below .5V)
Control Logic
Logic Supply Voltage Range
VDD
Logic Input Voltage
Operating
3
5.0
5.5
V
VIN(1)
VDD*.5
–
–
V
VIN(0)
–
–
VDD*.2
V
Logic Input Current
IIN(1)
VIN = VDD*.5
-20
<1.0
20
μA
(except ENABLE)
IIN(0)
VIN = VDD*.2
-20
<-1.0
20
μA
Logic Input Current
IIN(1)
VIN = VDD*.5
–
100
μA
ENABLE Input
IIN(0)
VIN = VDD*.2
–
30
μA
Internal Oscillator
fOSC
OSC shorted to GND
3
4
5
MHz
3.4
4
4.6
MHz
ROSC= 51K
Continued on the next page...
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A3936
DMOS Three-Phase PWM Motor Driver
ELECTRICALCHARACTERISTICS (continued) at TJ= +25°C, VBB = 50 V, VDD = 5.0 V, fPWM < 50KHz
(unless noted otherwise)
Limits
Characteristics
Sym bol
Test Conditions
M in.
Typ.
M ax.
Units
Control Logic
Buffer Input Offset Volt.
VIO
VREF Input Voltage Range
±10
mV
Operating
0.0
–
VDD
V
-.5
0
0.5
MA
Reference Input Current
IREF
VREF = VDD ,VBB=0 to 50V
Comparator Input Offset Volt.
VIO
VREF = 0 V
VERR
VREF = VDD
-4
4
%
(Note 3)
VREF = .5V
-14
14
%
GM Error
Propagation Delay Times
Crossover Delay
Thermal Shutdown Temp.
Thermal Shutdown Hysteresis
UVLO Enable Threshold
UVLO Hysteresis
tpd
±5
mV
50% TO 90%, SR Enabled
PWM CHANGE TO SOURCE ON
600
750
1000
ns
PWM CHANGE TO SOURCE OFF
50
150
350
ns
PWM CHANGE TO SINK ON
600
750
1000
ns
PWM CHANGE TO SINK OFF
50
100
150
ns
SR Enabled
300
600
1000
ns
TJ
–
165
–
°C
$TJ
–
15
–
°C
2.45
2.7
2.95
V
0.05
0.10
–
V
tCOD
Rising VDD
Continued on the next page...
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
A3936
DMOS Three-Phase PWM Motor Driver
ELECTRICALCHARACTERISTICS (continued) at TJ= +25°C, VBB = 50 V, VDD = 5.0 V, fPWM < 50KHz
(unless noted otherwise)
Limits
Characteristics
Sym bol
Test Conditions
M in.
Typ.
M ax.
Units
-1
0
1
MA
2.5
V
Hall Logic
Hall Input Current
IHALL
VIN = 1.2V
VCMR
.3
AC Input Voltage Range
VHALL
.120
Hysteresis
VHYS
Common Mode Input Range
TA= -20 to 85 deg C.
10
3
Pulse Reject Filter
Hall Bias Output Sat Voltage
VHB
IOUT=40mA, TA= -20 to 85 deg C.
IHB
Tach Output
NOTES: 1.
2.
3.
VOL
Vp-p
IOUT= 500uA
30
mV
5.5
8
Ms
.4
.5
V
40
mA
.5
V
Typical Data is for design information only.
Negative current is defined as coming out of (sourcing) the specified device pin.
VERR =((VREF/10) – VSENSE)/(VREF/10)
Commutation Truth Table
120 spacing
HB
HC
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
HA
1
2
3
4
5
6
1
2
3
4
5
6
DIR
FOR
FOR
FOR
FOR
FOR
FOR
REV
REV
REV
REV
REV
REV
X
X
OUTA
HI
HI
Z
LO
LO
Z
LO
LO
Z
HI
HI
Z
Z
Z
Outputs
OUTB OUTC
LO
Z
Z
LO
HI
LO
HI
Z
Z
HI
LO
HI
HI
Z
Z
HI
LO
HI
LO
Z
Z
LO
HI
LO
Z
Z
Z
Z
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
A3936
DMOS Three-Phase PWM Motor Driver
Functional Description
VREG. The VREG pin should be decoupled with a 0.22
μF capacitor to ground. This supply voltage is used to run
the sink side DMOS outputs. VREG is internally monitored
and in the case of a fault condition, the outputs of the device
are disabled.
Charge Pump. The Charge Pump is used to generate a
supply above VBB to drive the source side DMOS gates. A
0.22 uF ceramic monolithic capacitor should be connected
between CP1 and CP2 for pumping purposes. A 0.22 uF
ceramic monolithic capacitor should be connected between
VCP and VBB to act as a reservoir to run the high side
DMOS devices. The VCP Voltage is internally monitored
and in the case of a fault condition the outputs of the device
are disabled.
Shutdown. In the event of a fault due to excessive
junction temperature, or low voltage on VCP or VREG, the
outputs of the device are disabled until the fault condition is
removed. At power up, and in the event of low VDD, the
UVLO circuit disables the drivers.
Extmode Logic. When using external PWM current
control, the EXTMODE input determines the current path
during the chopped cycle. With EXTMODE set low, fast
decay mode, both the source and sink drivers are chopped
OFF during the decay time (ENABLE=0). With
EXTMODE high, slow decay mode, only the source driver
turns off during the current decay time.
EXTMODE
0
1
Decay
Fast
Slow
Sleep Mode. The input pin SLEEP is dedicated to put
the device into a minimum current draw mode. When
asserted low, all circuits are disabled.
Fixed Off-Time. The 3936 is set for a fixed off time of
96 counts of the internal oscillator, typically 24 μs with
4Mhz oscillator.
Internal Current Control Mode. Input pins PFD1
Current Regulation. Load current is regulated by an
internal fixed off time PWM control circuit. When the
outputs of the DMOS H-bridge are turned on, current
increases in the motor winding until it reaches a value given
by:
ITRIP = VREF/(10*RSENSE)
At the trip point, the sense comparator resets the source
enable latch, turning off the source driver. At this point,
load inductance causes the current to recirculate for the
fixed off time period. The current path during recirculation
is determined by the configuration of slow/mixed decay
mode and the synchronous rectification control setting.
and PFD2 determine the current decay method after an
overcurrent event is detected at sense input. In slow decay
mode both sink side drivers are turned on for the fixed off
time period. Mixed decay mode starts out in fast decay
mode for the selected percentage of the fixed off time, and
then is followed by slow decay for the rest of the period.
PFD2
0
0
1
1
PFD1
0
1
0
1
% tOFF
0
15
48
100
Decay
Slow
Mixed
Mixed
Fast
Enable Logic. The Enable input terminal allows
external PWM. ENABLE high turns ON the selected sinksource pair, enable low switches off the appropriate drivers
and the load current decays. If the ENABLE pin is held
high, the current will rise until it reaches the level set by the
internal current control circuit.
ENABLE
0
1
Outputs
Source
Chopped
ON
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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A3936
DMOS Three-Phase PWM Motor Driver
PWM Blank Timer. When a source driver turns on, a
current spike occurs due to the reverse recovery currents of
the clamp diodes and/or switching transients related to
distributed capacitance in the load. To prevent this current
spike from erroneously resetting the source enable latch, the
sense comparator is blanked. The blank timer runs after the
off time counter to provide the blanking function. The blank
timer is reset when ENABLE is chopped or DIR is changed.
For external PWM control, a DIR change or ENABLE ON
will trigger the blanking function. The duration is adjusted
by control input BLANK.
BLANK
0
1
tBLANK
6/f OSC
12/f OSC
Synchronous Rectification. Logic high applied to
the SR terminal enables synchronous rectification. When a
PWM off cycle is triggered, either by an ENABLE chop
command or internal fixed off time cycle, load current will
recirculate according to the decay mode selected by control
logic. The A3936 synchronous rectification feature will turn
on the appropriate MOSFET(s)during the current decay and
effectively short out the body diodes with the low Rdson
driver. This will lower power dissipation significantly and
can eliminate the need for external schottky diodes.
Reversal of load current is prevented by turning off
synchronous rectification when a zero current level is
detected.
Brake. Logic high to the brake terminal activates the
brake function, logic low allows normal operation. Brake
will turn all three sink drivers ON and effectively shorts out
the motor generated BEMF. It is important to note that the
internal PWM current control circuit will not limit the
current when braking, since the current does not flow
through the sense resistor. The maximum current can be
approximated by VBEMF/RL. Care should be taken to insure
that the maximum ratings of the device are not exceeded in
worse case braking situations of high speed and high
inertial loads.
Oscillator. The PWM timer is based on an internal
oscillator set by a resistor connected from the OSC terminal
to VDD. Typical value of 4Mhz is set with 51k resistor.
FOSC = 204E9/ROSC.
Tach. A tachometer signal is available for speed
measurement. This open collector output toggles at each
Hall transition.
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
A3936
DMOS Three-Phase PWM Motor Driver
40 EXTMODE
41 BLANK
42 PFD2
43 PFD1
1 GND
44 GND
2 GND
3 HA+
4 HA-
5 HB+
6 HB-
Pin-out Diagram
HC+
7
39 ENABLE
HC-
8
38 DIR
VDD
9
37 VREG
REF 10
36 OSC
GND 11
35 GND
GND 12
34 GND
GND 13
33 GND
OUTC 28
TACH 27
LSS2 25
VBB2 26
GND 24
GND 23
GND 22
29 VCP
OUTB 21
30 CP1
OUTA 17
LSS1 20
31 CP2
SR 16
VBB1 19
32 SLEEP
SENSE 15
HBIAS 18
BRAKE 14
Terminal List
Pin No.
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
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Pin Name
GND
GND
HA+
HAHB+
HBHC+
HCVDD
REF
GND
GND
GND
BRAKE
SENSE
SR
OUTA
HBIAS
VBB1
LSS1
OUTB
GND
GND
GND
LSS2
VBB2
TACH
OUTC
VCP
CP1
CP2
SLEEP
GND
GND
GND
OSC
VREG
DIR
ENABLE
EXTMODE
BLANK
PFD2
PFD1
GND
Pin Description
Hall input
Hall input
Hall input
Hall input
Hall input
Hall input
Logic Supply Voltage
Gm Reference Input Voltage
Logic Input
Sense Resistor Connection
Logic Input (Disabled = Low, Active SR = High)
DMOS H – Bridge A
Connection for hall element neg side
Load Supply Voltage
Low Side Source connection
DMOS H – Bridge B
Low Side Source connection
Load Supply Voltage
Speed output
DMOS H – Bridge C
Reservoir Capacitor Terminal
Charge Pump Capacitor Terminal
Charge Pump Capacitor Terminal
Logic input for SLEEP mode
Oscillator Terminal
Regulator decoupling Terminal
Logic Input
Logic Input
Logic Input
Logic Input
Logic Input
Logic Input
Power Ground Tab
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
A3936
DMOS Three-Phase PWM Motor Driver
Package ED 44-Pin PLCC
17.53 ±0.13
16.59 ±0.08
0.51
2 1 44
7.75 ±0.36
A
17.53 ±0.13 16.59 ±0.08
7.75 ±0.36
0.74 ±0.08
4.57 MAX
44X
SEATING
PLANE
0.10 C
0.43 ±0.10
C
1.27
7.75 ±0.36
7.75 ±0.36
For Reference Only
(reference JEDEC MS-018 AC)
Dimensions in millimeters
Internally fused pins: 1, 2, and 44; 11, 12, and 13; 22, 23, and 24; and 33, 34, and 35.
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
A Terminal #1 mark area
Copyright ©2002-2009, Allegro MicroSystems, Inc.
The products described here are manufactured under one or more U.S. patents or U.S. patents pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the
information being relied upon is current.
Allegro’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use;
nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
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