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Part: 8932
Category:
Description:
Company: Allegro Micro Systems, Inc.
Datasheet: Download 8932 datasheet File size : 421 kB
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Datasheet text preview:
8932-A
RET REF V FLT V BEMF GROUND UV SET R OUT P OUT SWITCH IN N OUT SW RETRACT FAULT MP RESET SIGNAL SUPPLY 1 2 3 4 5 6 28 27 RET SET V SENS V LOAD
VOICE-COIL MOTOR DRIVER
Providing control and drive of the voice-coil motor used for head positioning in 5 V disk drive applications, the second-generation A8932CLWA is a full-bridge driver that can be configured so that its output current is a direct function of an externally applied control voltage or current. This linear current control function is supplemented by additional circuitry to protect the heads and the data disk during system failure or normal system shutdown. The two ±500 mA MOS driver outputs provide very low saturation voltage and minimal power dissipation. Additional headroom is achieved by the sense-FET structure eliminating the need for an external current-sense resistor. Internal circuitry can be configured to provide closed-loop velocity control of the actuator by utilizing the generated back-EMF of the voice-coil motor. Thermal protection and under-voltage lockout disables the system in a controlled sequence if a fault condition occurs.
Data Sheet 26300.2A
PROTECT CIRCUIT
26 25 24 23
7 8
10 11
12 13
14
ABSOLUTE MAXIMUM RATINGS
Supply Voltages, VCC and VDD ... 6.0 V Output Current, IOUT (peak) .. ±600 mA (continuous) ... ±500 mA Analog Input Voltage Range, VIN ... -0.3 V to VCC Logic Input Voltage Range, VIN ....... -0.3 V to +6.0 V Package Power Dissipation, PD ........ See Graph Operating Temperature Range, TA .... 0°C to +70°C Junction Temperature, TJ ...... +150°C Storage Temperature Range, TS ........ -55°C to +150°C
Fault conditions that produce excessive junction temperature will activate device thermal shutdown circuitry. These conditions can be tolerated, but should be avoided. Output current rating may be restricted to a value determined by system concerns and factors. These include: system duty cycle and timing, ambient temperature, and use of any heatsinking and/or forced cooling. For reliable operation the specified maximum junction temperature should not be exceeded.
E L B AE IL AL AS V AL R RA EE GN NE OG L O OR NF
+
V SENS FB SGND N OUTP VDD 22 LOAD SUPPLY OUT N 21 20
+
9
V REF
+
SGND P ACT FB
2V
19 18 17 16 15
PWR OFF H GAIN
PROTECT CIRCUIT
+
REFERENCE ACT
V CC
FEATURES
s s s s s s s s s s s
Dwg. PP-042B
Class-B, 2 rDS(on) at 500 mA Output Lossless Current Sensing Zero Current-Loop Deadband High Transconductance Bandwidth User-Adjustable Transconductance Gain Digital Transconductance Gain Switch (4:1 Ratio) 5 Volt Monitor with Selectable UV Trip Point Retract Circuitry Functional to 0 Volts Sleep Mode Function Internal Back-EMF Velocity Loop Option Internal Thermal Shutdown Circuitry
Always order by complete part number, e.g., A8932CLWA .
8932-A VOICE-COIL MOTOR DRIVER
FUNCTIONAL BLOCK DIAGRAM
SIGNAL SUPPLY
14
LOAD SUPPLY
22
V CC ACT FB
19 I SENSE +
VDD
VOLTAGE-SENSE AMP
+
26 20 23 21 24
V LOAD SGND P OUT P OUT N SGND N V SENS FB V SENS IN N OUT OUT SW
ACT 15 REFERENCE 16 H GAIN 17
ERROR AMP
POWER AMP
REF.
+
2V POWER CONTROL LOGIC
+
PWR OFF 18
CURRENT-SENSE AMP
I SENSE
25 27 9 7
+
TSD FAULT 12 MP RESET 13 PROTECTION CIRCUITRY RETRACT CONTROL
REF.
REF.
6 4
10
+
8
5
3
2
28
1
11
RETRACT
VBEMF
UVSET
RET REF
RET SET
R OUT P
VFLT
GROUND
SWITCH
Dwg. FP-024D
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
2.0
1.5
/W R, C AI 66° EE = FR JA R
1.0
0.5
0
25
50 75 100 125 AMBIENT TEMPERATURE IN °C
150
Dwg. GP-034
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 1992, 2001 Allegro MicroSystems, Inc.
8932-A VOICE-COIL MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = +25°C, VCC = VDD = 5.0 V, VREF = VIN = 2.0 V, Load = 150 µH/3.5 (unless otherwise noted).
Limits Characteristic Error Amplifier Input Offset Voltage Current Gain VIO AiH AiL Current Gain Linearity EL(adj) ILOAD = 0 mA H GAIN 3.5 V H GAIN 0.7 V IOUT = 5 mA to 500 mA, Ai = AiL IOUT = 5 mA to 500 mA, Ai = AiH Reference Voltage Range Voltage-Sense Amplifier Voltage Gain Output Offset Voltage Current-Sense Amplifier Amplifier Error Input Offset Voltage Output Drivers Total On Resistance (Source + Sink) Retract Output Voltage Error Full Power Bandwidth Uncommitted Op Amp Voltage Gain Unity Gain Bandwidth Max. Load Capacitance Slew Rate Output Voltage AVS BW CLOAD SR VO VOSW Max. Output Current Input Offset Voltage IO VIO VSWITCH 0.7 V VSWITCH 3.5 V -- -- -- -- 2.5 2.5 -- -- 91 1.0 40 4.2 -- -- ±250 <±10 -- -- -- -- 3.5 3.5 -- -- dB MHz pF V/µs V V µA mV EOUT(PN) BW EVD ViO (Rs x ILOAD / (Ai x VSENSE)) - 1 ILOAD = 0 mA, Ai = AiL -- -- 1.0 -- -- ±25 -- mV AVD VOO ILOAD = 0 mA 0.36 -- 0.40 -- 0.44 ±25 -- mV VREF -- 7200 1800 -- -- 1.5 -- 8000 2000 -- -- -- ±50 8800 2200 ±10 ±10 2.5 mV -- -- % % V Symbol Test Conditions Min. Typ. Max. Units
r DS(on)
ILOAD = 100 mA ILOAD = 500 mA VOUT(P) - VOUT(N) - VRETSET -3 dB
-- -- -- 1.0
2.0 2.0 -- --
2.5 2.5 ±100 --
mV kHz
Continued next page...
Negative current is defined as coming out of (sourcing) the specified device terminal. Typical Data is for design information only.
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8932-A VOICE-COIL MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = +25°C, VCC = VDD = 5.0 V, VREF = VIN = 2.0 V, Load = 150 µH/3.5 (unless otherwise noted).
Limits Characteristic Miscellaneous Supply Voltage VCC VDD Under-Voltage Lockout Voltage Fault Logic Output VCC VFAULT Operating Operating VCC = VDD VRETRACT 3.5 V VRETRACT 0.7 V IFAULT Power-On Reset VMPRESET VFLT = 2.25 V VRETRACT 3.5 V VRETRACT 0.7 V, IMPREST = 1.5 mA Total Supply Current ICC + IDD Outputs Balanced, No Load Sleep Mode, PWR OFF = VCC Logic Input Voltage VIN(0) VIN(1) Thermal Shutdown Temperature Thermal Shutdown Hysteresis TJ T J 4.5 4.5 3.9 -- 4.5 -- 4.5 -- -- -- -- 3.5 -- -- 5.0 5.0 4.2 -- -- >20 -- -- -- -- -- -- 165 20 5.5 5.5 4.35 500 -- -- -- 800 10 2.0 0.7 -- -- -- V V V mV V µA V mV mA mA V V °C °C Symbol Test Conditions Min. Typ. Max. Units
Negative current is defined as coming out of (sourcing) the specified device terminal. Typical Data is for design information only.
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 products are not authorized for use as critical components in life-support devices or systems without express written approval. 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.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
8932-A VOICE-COIL MOTOR DRIVER
TERMINAL FUNCTIONS
Term. 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 Terminal Name RET REF VFLT VBEMF GROUND UVSET ROUT P OUT SWITCH INN OUTSW RETRACT FAULT MPRESET SIGNAL SUPPLY ACT REFERENCE H GAIN PWR OFF ACTFB SGNDP OUTN LOAD SUPPLY OUTP SGNDN VSENS FB VLOAD VSENS RET SET Function The reference supply for setting the voltage across the load during retract. Reservoir (energy storage) capacitor used to operate fault circuitry. Back-EMF voltage from spindle motor used to retract heads during loss of power. Circuit reference. Under-voltage trip point reference input. Set internally to 4.2 V but may be overridden by external resistor divider. (Equation 4). Source driver used for retract; externally connected to OUTP. Output of uncommitted operational amplifier. Logic input for transmission gate; a high level connects OUT to OUTSW. Inverting input to uncommitted operational amplifier. Transmission-gated output of uncommitted operational amplifier. An active-low logic input that initiates the retract sequence. A logic low at this MOS output indicates a thermal shutdown, under-voltage fault, or retract command. (Power-On Reset) A logic low at this open-collector output may be used to reset the system on under-voltage fault or power on. VCC; low-current supply voltage in the range of 4.5 V to 5.5 V. Input which controls the current in the load. Transconductance gain is set with an external resistor in series with this input (Equation 1). VREF; reference input for all amplifiers; ac ground. Logic input to switch the error amplifier transconductance gain: LOW = 2000, HIGH = 8000. An active-high logic input that puts the device in a "sleep mode". All fault circuitry remains active. Input connection for feedback network which sets the error amplifier gain and bandwidth. Power ground for the OUTP sink driver. Power output. Sinks current when VACT VREF. Power ground for the OUTN sink driver. Input connection for feedback network which sets the current-sense amplifier gain and bandwidth. Also called gm SET. An output voltage proportional to the load voltage. Used in conjunction with closed-loop velocity control. Voltage output representing load current (Equation 2). Also called MONITOR. An external resistor divider to set the retract voltage across the load. Used in conjunction with VRET-REF (Equation 3).
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89-1
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