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Details, datasheet, quote on part number:3938
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Datasheet text preview:
3938
PRELIMINARY DATASHEET - 11/07/02 (Subject to change without notice)
THREE PHASE POWER MOSFET CONTROLLER
The A3938 is a three-phase, brushless, DC-motor controller. The A3938's high current gate drive capability allows driving of a wide range of power MOSFETs and can support motor supply voltages to 50V. The A3938 integrates a bootstrapped high side driver to minimize the external component count required to drive N-channel MOSFET drivers. Internal, fixed, off-time, PWM, current-control circuitry can be used to regulate the maximum load current to a desired value. The peak load current limit is set by the user's selection of an input reference voltage and external sensing resistor. A user-selected external RC timing network sets the fixed off-time pulse duration. For added flexibility, the PWM input can provide speed/torque control where the internal current control circuit sets a limit on the maximum current. The A3938 includes Synchronous Rectification. This feature shorts out the current path through the power MOSFET's reverse body diodes during PWM off cycle current decay. This can minimize power dissipation in the MOSFETs, eliminate the need for external power clamp diodes, and potentially allow a more economical choice for the MOSFET drivers. The A3938 provides commutation logic for Hall sensors configured for 120-degree spacing. The Hall input pins are pulled up to an internally generated 5V reference. Power MOSFET protection features includes bootstrap capacitor charging current monitor, regulator under-voltage monitor, motor lead short-to-ground, and thermal shutdown. The A3938 is available in a choice of two packages: a 32-pin, rectangular PLCC suffix "EQ"; and 36-pin, QSOP, suffix "LQ".
ABSOLUTE MAXIMUM RATINGS ( at TA = +25°C )
Load Supply Voltage, VBB .... 50 V VREG (Transient) ........ 15 V Logic Input Voltage Range, VIN.......... -0.3 V to VLCAP + 0.3 V Sense Voltage, VSENSE ....... -5 to 1.5 V Pins SA/SB/SC, ... -5 to 50 V Pins GHA/GHB/GHC ....... -5 to VBB + 17 V Pins CA/CB/CC ....... SA/SB/SC+17 V
Operating Temperature Range, TA ........ -20°C to +85°C Junction Temperature, TJ ....... +150°C Storage Temperature Range, TS ...... -55°C to +150°C
° Thermal Impedances, typ. (TA = +25°C)*
A3938SEQ, RØJA .... 37 °C/W A3938KLQ, RØJA .... 44 °C/W * JEDEC High K board.
T
FEATURES
Drives Wide Range of N-channel MOSFETs T Low-Side Synchronous Rectification T Power MOSFET Protection T Adjustable Dead-Time for CrossConduction Protection T Selectable coast or dynamic brake on power-down or RESET input T Fast/Slow Current Decay Modes T Internal PWM Current Control
T
Motor Lead Short-to-Ground Protection T Internal 5V Regulator T Fault Diagnostic Output T Thermal Shutdown T Under-voltage Protection
3938 Three Phase MOSFET Controller
Functional Block Diagram (1 of 3 outputs shown)
VBB
LCAP
Regulator
0.1 uF H1
VREG + 10 uF
0.1 uF
Charge Pump
CA
H2
CBOOT
0.1 uF
H3
PWM
Control Logic
High Side Protection Logic
TurnOn Delay
High Side Driver
To Phase C GHA
DIR
RESET SA BRAKE MODE VREG
RC CT RT
RC Blanking Fixed - Off Time
Low Side Protection Logic
Turn-on Delay
Low Side Driver
GLA
To Phase B
+
SENSE RS
PGND to LCAP DEAD
REF
Dead-Time Adjust
Short to GND VREG TSD Invalid Hall VREG_Under-voltage FAULT O.D.
BRKCAP + 4.7uF BRKSEL
Power Loss Brake
VREGUVLO RESET
AGND
3938_3OCT02
Note: For 12V applications, VBB must be shorted to VREG. For this condition, the absolute max rating of 15V on VREG must be maintained to prevent damage to the 3938.
3938 Three Phase MOSFET Controller
ELECTRICAL CHARACTERISTICS: Unless noted, otherwise: TA = 25°C, Vbb = 18 to 50 V, Clcap, Cboot = 0.1 uF, Cvreg = 10 uF, PWM = 22.5 kHz sq. wave, two phases active. Typ. values for design use, only. Negative current flows out of designated pin.
Characteristics
Quiescent Current LCAP Regulator VREG =VBB Supply Voltage Range VREG Output Voltage
Symbol
I VBB VLCAP VREG VREG
Test Conditions
RESET = 1, Coast mode, Stopped. Ilcap = -3.0 mA VREG =VBB, observe max. rating = 15 V VBB = 13.2 to 18 V, Ivreg = -10 mA. VBB = 18 to 50V, Ivreg = -10 mA.
Min.
Typ.
Max.
8.0
Units
mA V V V
4.75 10.8
5 VBB-2.5
5.25 13.2
12.4
13 25
13.6
V mV
VREG Load Regulation VREG Line Regulation
VREGLOAD VREGLIN
Ivreg = -1 to -30 mA, Coast. Ivreg = -10 mA, Coast.
40
mV
Control Logic
Logic Input Voltage VIN(1) VIN(0) Logic Input Current IIN(1) IIN(0) Minimum High Level for Logical (1) Maximum Low Level for Logical (0) VIN = 2.0 V VIN = 0.8 V 2.0 -30 -50 0.8 -90 -130 V V µA µA
Gate Drive
Low side drive, output high High side drive, output high Pull Up Switch Resistance Pull Down Switch Resistance Low side switching, 10/90 rise time Low side switching, 10/90 fall time High side switching, 10/90 rise time High side switching, 10/90 fall time Prop. Delay, GHx,GLx rising Prop. Delay, GHx,GLx falling Dead time, maximum Dead time, minimum VHGL V HGH RDS(ON) RDS(ON) trGL t fGL trGH t fG H Tpr Tpf tDEAD tDEAD Igx = 0 Igx = 0 Igx = - 50mA Igx = 50mA Cload = 3300 pF Cload = 3300 pF Cload = 3300 pF Cload = 3300 pF PW M to Gate Drive Out. Cload = 3300 pF PW M to Gate Drive Out. Cload = 3300 pF IDEAD = 10µA, GHx to GLx, Cload =3300 pF. IDEAD = 780µA, GLx to GHx, Cload =3300 pF. VREG-.8 10.4 VREG-.5 11.6 12.8 V V ns ns ns ns nS nS ns ns
14 4
120 60 120 60 220 110 5500 100
3938 Three Phase MOSFET Controller
Characteristics Bootstrap Capacitor
Bootstrap Capacitor Voltage Bootstrap Capacitor ROUT Charge Current
Symbol
Test Conditions
Min.
Typ.
Max.
Units
VCAP RCAP ICX
Icx = 0. Vsx = 0, Vreg = 13 V. Icx = -50 mA
10.4
11.6 9
12.8 12
V mA
100
Current Limit Circuitry
Input Offset Voltage Input Current , Sense pin Input Current , Ref. pin Blank Time RC Charge Current RC Voltage Threshold VIO IB IB tBLANK IRC VRCL VRCH 0 V < Vcmr < 1.5 V 0 V < Vcm, Vdiff < 1.5 V. [200K pull-up] 0 V < Vcm, Vdiff < 1.5 V R=56k, C= 470pf -0.9 1.0 2.7 -5 0 -25 0 .91 -1 1.1 3.0 -1.1 1.2 3.3 5 mV µA µA µs mA V V
Protection Circuitry
Bootstrap Charge Threshold Short to Ground, Drain-Source Monitor VREG Under-voltage Threshold IBOOTCHG UVLODS GHx turns ON, GLx turns OFF at IBOOTCHG VBB - VSX, High Side ON 1.3 -9 2.0 2.7 mA V
UVLO UVLO
VREG low to High VREG High to Low IOL = 1mA VBB = 8V, BRKSEL = 1 VBB=0, BRKCAP = 8V
9.2 8.6
9.7 9.1
10.2 9.6 0.5
V V V µA V
Fault Output Voltage Brake Capacitor Supply Current Low Side Gate Voltage
VOUT IBRAKE VGLBH
30 6.6
Thermal Shutdown Temp. Thermal Shutdown Hysteresis
TJ TJ
165 10
°C °C
3938 Three Phase MOSFET Controller
Pin Descriptions
RESET. A logic input that enables the device. Has internal 50K pull-up to LCAP. RESET=1 will coast or brake the motor depending on the state of the BRKSEL pin. RESET=0 will enable gate drive to follow commutation logic. RESET = 1 will override the BRAKE pin. GLC/GLB/GLA. Low-side gate drive outputs for external MOSFET drivers. External series gate resistors can be used to control slew rate seen at the power driver gate, thereby, controlling the di/dt and dv/dt of S outputs. SC/SB/SA. Directly connected to the motor terminals,
these pins sense the voltages switched across the load. The pins are also connected to the negative side of the bootstrap capacitors and the negative supply connections for the floating high-side drivers.
FAULT. Open collector output to indicate fault condition. Will be pulled HIGH (usually by 5.1K external pull-up) for any of the following fault conditions:
1) 2) 3) 4) Invalid HALL input code. Under-voltage condition detected at VREG. Thermal Shutdown. Motor lead (SA/SB/SC) connected to ground.
Faults will force a COAST condition that turns all power MOSFETs off except a "Short-to-Ground" Fault that only turns off the high-side drivers. Only the "Short-to-Ground" Fault is latched but is cleared at each commutation. If the motor has stalled due to a short to ground being detected, toggling the RESET pin or repeating a power-up sequence will clear the fault.
GHC/GHB/GHA. High-side gate drive outputs for Nchannel MOSFET drivers. External series gate resistors can be used to control slew rate seen at the power driver gate, thereby, controlling the di/dt and dv/dt of S outputs.
BRAKE. Logic input for braking function. BRAKE=1 will
turn on sink-side MOSFETs, turn off the source-side MOSFETs. This will effectively short the BEMF in the windings and brake the motor. Internal, 50K pull-up to LCAP. RESET=1 overrides this BRAKE pin. See BRKSEL.
CC/CB/CA. High-side connections for bootstrap capacitors, positive supply for high-side gate drivers. The bootstrap capacitors are charged to approximately VREG when the output Sx terminals go low. When the output swings high, the voltage on these pins rise with the outputs to provide the boosted gate voltages needed for N-channel power MOSFETs. MODE. Logic input to set current decay method. In
response to PWM Off command: Slow Decay Mode (MODE=1) switches off the high-side FET, Fast Decay Mode (MODE=0) switches off the high-side and low-side FETs. Has internal, 50K pull-up to LCAP.
BRKCAP. This pin is for connection of the reservoir capacitor used to provide positive power supply for the sink drive outputs for a power down condition. This will allow predictable braking, if desired. A 4.7µF capacitor will provide 6.5V gate drive for 300ms. If power down braking option is not needed (i.e., BRKSEL=0) then this pin should be tied to VREG. BRKSEL. Logic input to enable/disable braking upon
power down condition or RESET =1. Internal, 50K pull-up to LCAP. BRKSEL: 0 = Coast, 1 = Brake.
PWM. Speed control input. PWM=1 will turn on
MOSFETs selected by Hall input logic. PWM=0 turns off the selected MOSFETs. The PWM input held high to utilize internal current control circuitry. Internal, 50K pull- up to LCAP.
H1/H2/H3. Hall sensor inputs with internal, 50K pull-ups
to LCAP. Configured for 120-degree electrical spacing.
DIR. Logic input to reverse rotation, see Commutation
Logic Table. Has internal, 50K pull-up to LCAP.
RC. Analog input. Connection for RT and CT to set the fixed
off-time. The CT will also set the BLANK time. (see Applications Information). It is recommended that the fixed off-time should not be less than 10 uS. The resistor should be in the range 10K to 500K.
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