8936 INTERIM DATA SHEET Data Sheet 26300.6 8936 VOICE COIL MOTOR DRIVER (Subject to change without notice) March 16, 1993 VOICE COIL MOTOR DRIVER A8936CLW RET REF 1 V FLT 2 V BEMF 3 PROTECT R CIRCUIT S Q 28 RET SET 27 V SENS 26 VEL FLT Providing control and drive of the voice coil motor used for head positioning in 5 V disk drive applications, the A8936C— is a full-bridge driver which 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. An under- or over-velocity sense disables the system in a controlled sequence if a fault condition occurs. T C U Y D L O N R O P E D C E N U E N ER I T F N E O R C S OR I D F — GROUND 4 UV SET 5 R OUT P 6 WINDOW 25 V SENS FB 24 SGND N 23 OUTP 22 LOAD SUPPLY COMP. V REF + – VREF OUT 7 EN VEL FLT 8 21 OUT N IN N 9 20 SGND P VEL IN 10 19 ACT FB RETRACT 11 18 PWR OFF 17 H GAIN 16 REFERENCE 15 ACT FAULT 12 MP RESET 13 SIGNAL SUPPLY 14 VDD PROTECT CIRCUIT + – V CC Dwg. PP-046A 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 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. Thermal protection and under-voltage lockout disables the system in a controlled sequence if a fault condition occurs. FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Over-Velocity Fault Function Lossless Current Sensing Zero 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 Chip Enable/Sleep Mode Function 1 V at 500 mA Output Saturation Voltage Internal Thermal Shutdown Circuitry † 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. Always order by complete part number: Part Number Package A8936CJT 64-Lead Thin Quad Flatpack A8936CLW 28-Lead SOIC A TM MicroSystems, Inc. 8936 VOICE COIL MOTOR DRIVER FUNCTIONAL BLOCK LOAD SUPPLY 14 53 22 V CC ACT FB 19 1 8 V REF VDD I SENSE + ERROR – AMP ACT 15 55 POWER CONTROL LOGIC PWR OFF 18 62 CURRENT-SENSE AMP I SENSE – – V REF TSD FAULT 12 50 R 9 IN N 28 27 23 25 47 34 19 30 5 3 2 28 1 11 6 26 4 OUT P 21 OUT N 15 24 SGND N 16 25 V SENS FB 21 27 V SENS 46 10 VEL IN V REF 8 EN VEL FLT GROUND VEL FLT R OUT P 33 SGND P 13 23 36 RETRACT Q WINDOW COMP. RET REF S V FLT Q VBEMF RETRACT CONTROL RET SET 45 + UVSET MP RESET 13 51 PROTECTION CIRCUITRY OUT 4 – 2V H GAIN 17 60 7 2 20 POWER AMP + + REFERENCE 16 58 35 – = 'JT' THIN QUAD FLATPACK + SIGNAL SUPPLY = 'LW' WIDE-BODY SOIC DIAGRAM Dwg. FP-030A V CC + PROTECT. CIRCUIT — 1.5 /W R, C AI 66° EE = FR JA R θ ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS A8936CJT 2.0 1.0 V V REF DD + — V REF WINDOW COMP. 0.5 S 0 Q 25 50 75 100 125 AMBIENT TEMPERATURE IN °C 150 R RETRACT CONTROL PROTECT. CIRCUIT Dwg. GP-034 Dwg. PP-052-1 A TM MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Worcester,©Massachusetts 01615-0036 (508) 853-5000 Copyright 1992, 1993, Allegro MicroSystems, Inc. 8936 VOICE COIL MOTOR DRIVER ELECTRICAL CHARACTERISTICS at TA = +25°C, VCC = V DD = 5.0 V, VREF = VIN= 2.0 V, Load = 150 µH/3.5 Ω (unless otherwise noted). Characteristic Symbol Test Conditions Min. Limits Typ. Max. Units Error Amplifier Input Offset Voltage V IO ILOAD = 0 mA Current Gain A iH A iL Current Gain Linearity E L(adj) Reference Voltage Range VREF — — 50 mV H GAIN ≥ 3.5 V 7200 8000 8800 — H GAIN ≤ 0.7 V 1800 2000 2200 — — — ±10 % IOUT = 5 mA to 500 mA, Ai = A iL IOUT = 5 mA to 500 mA, Ai = A iH — — ±10 % 1.5 — 2.5 V Current-Sense Amplifier Voltage Gain A VD Rs = Rgm — 1.0 — — Input Offset Voltage ViO ILOAD = 0 mA, A i = AiL — — ±25 mV — V Output Drivers Output Saturation Voltage (Source + Sink) V DS(SAT) Retract Output Saturation Voltage V DS(SAT) Output Current Full Power Bandwidth IO BW ILOAD = 100 mA — 0.25 ILOAD = 500 mA — 1.5 — V IOUT ≤ 150 mA — — 1.0 V Pulse Test, ±600 mA Limited — — ±500 mA -3 dB 1.0 — — kHz Window Comparator Lower Trip Point VEL IN 1.12 1.25 1.38 V Upper Trip Point VEL IN 2.47 2.75 3.03 V Voltage Gain AVS — 91 — dB Unity Gain Bandwidth BW — 1.0 — MHz CLOAD 40 — — pF Slew Rate SR — 4.2 — V/µs Output Voltage VO 2.5 — 3.5 V Max. Output Current IO — ±250 — µA Input Offset Voltage V IO — — ±10 mV Uncommitted Op Amp Max. Load Capacitance VIO = 100 mV Continued next page … Negative current is defined as coming out of (sourcing) the specified device terminal. Typical Data is for design information only. 8936 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 Ω (unless otherwise noted). Characteristic Symbol Test Conditions Min. Limits Typ. Max. Units Miscellaneous Under-Voltage Lockout Voltage VCC Fault Logic Output V FAULT IFAULT Power-On Reset V MPRESET Total Supply Current ICC + IDD V CC = V DD 3.9 4.2 4.35 V V RETRACT ≥ 3.5 V — — 500 mV V RETRACT ≤ 0.7 V 4.5 — — V V FLT = 2.25 V 20 — — µA V RETRACT ≥ 3.5 V 4.5 — — V V RETRACT ≤ 0.7 V, IMPRESET = 1.5 mA — — 800 mV Outputs Balanced, No Load — — 10 mA Sleep Mode, PWR OFF = VCC — — 2.0 mA V IN(0) — — 0.7 V V IN(1) 3.5 — — V Thermal Shutdown Temperature TJ — 165 — °C Thermal Shutdown Hysteresis ∆T J — 20 — °C Logic Input Voltage Negative current is defined as coming out of (sourcing) the specified device terminal. Typical Data is for design information only. A TM MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 8936 VOICE COIL MOTOR DRIVER TERMINAL "JT" Term."LW" Term. Term. Name FUNCTIONS Function 25 1 RET REF The reference supply for setting the voltage across the load during retract. 27 2 VFLT 28 3 VBEMF 30 4 GROUND 33 5 UVSET Under-voltage trip point reference input. Set internally to 4.3 V but may be over-ridden by external resistor divider. (Equation 4). 34 6 R OUT P Source driver used for retract; externally connected to OUTP. 35 7 OUT 36 8 EN VEL FLT 45 9 INN Inverting input to uncommitted operational amplifier. 46 10 VELIN Analog voltage input corresponding to motor speed. 47 11 RETRACT 50 12 FAULT 51 13 MPRESET 53 14 55 15 58 16 60 17 H GAIN 62 18 PWR OFF 1 19 ACTFB Input connection for feedback network which sets the error amplifier gain and bandwidth. 2 20 SGNDP Power ground for the OUTP sink driver. 4 21 OUTN 8 22 13 23 OUTP 15 24 SGNDN 16 25 V SENS FB Input connection for feedback network which sets the current-sense amplifier gain and bandwidth. Also called gm SET. 19 26 VEL FLT An active-low logic output indicating an over-velocity fault. 21 27 V SENS 23 28 RET SET 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. Output of uncommitted operational amplifier. Logic input for over-velocity fault latch. 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. SIGNAL SUPPLY VCC ; low-current supply voltage in the range of 4.5 V to 5.5 V. ACT Input which controls the current in the load. Transconductance gain is set with an external resistor in series with this input (Equation 1). REFERENCE VREF; reference input for all amplifiers; ac ground. Logic input to switch the error amplifier transconductance gain: LOW = 2100, HIGH = 8400. An active-high logic input that puts the device in a “sleep mode”. All fault circuitry remains active. Power output. Sinks current when VACT < VREF. LOAD SUPPLY VDD ; high-current supply voltage for the voice-coil motor. Power output. Sinks current when VACT > VREF. Power ground for the OUTN sink driver. 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). 8936 VOICE COIL MOTOR DRIVER DEVICE DESCRIPTION Current Amplifier. The A8936CJT and A8936CLW voice coil motor drivers feature a wide transconductance bandwidth and no measurable crossover distortion. The transconductance gain is user selectable: gm = Ai Rgm (Equation 1) where Ai is either 2000 (H GAIN = Low) or 8000 (H GAIN = High) The error amplifier’s bandwidth and load compensation zero are set utilizing external resistor and capacitor feedback components around the amplifier. The actuator main loop compensation can be set by applying a square wave and adjusting R Z and CZ for optimum response. Current and Voltage Sensing. The load current is sensed internally. Two auxiliary amplifiers are also included to allow various control functions to be implemented. The first of these amplifiers provides a voltage output that is proportional to the load current: V SENS = RS ILOAD AiL (Equation 2) The second auxiliary amplifier may be used in conjunction with the first to provide a closed-loop velocity control system for the actuator arm during a controlled retract for head parking. Under- & Over-Velocity Fault. For a constant load, motor current (ILOAD) and therefore VSENS are proportional to motor velocity. VSENS is amplified by the uncommitted amplifier and compared against the internal 2 V reference and used to indicate a velocity fault if the voltage is greater than a nominal ±0.75 V from the 2 V reference. EN VEL FLT may be tied to the FAULT terminal to reset the velocity fault after a tripout. Retract and Brake. A retract-brake sequence is initiated on receiving a fault indication from the internal thermal shutdown (TSD), under-voltage lockout (UVLO), the under- or over-velocity fault, or an externally applied logic High at the RETRACT input. A If the velocity control scheme is implemented, the head can be retracted under the full control of INPUT in conjunction with OUTSW back-EMF voltage if no fault condition exists. If a fault condition were to occur however, the retract velocity would be controlled by applying a constant user-defined voltage across the load: V RET-SET = 2 R8 1000 + R7 + R8 where R7 + R8 >> 1000 Ω. When the sequence is operated, the output voltage is forced to approximately VRET-SET to retract the heads, and then a fault command (“brake”) is sent to the spindlemotor driver. The user determines the total time for the retract sequence, before the spindle brake is enabled, by the choice of an external resistor and capacitor at the FAULT output. Power for the retract function is provided by the rectified back EMF of the spindle motor by way of the VBEMF terminal. The A8936CJT/CLW will perform the retract function under low supply conditions (nominally down to 2 V). Operation down to almost 0 V requires an energy-storage capacitor at the VFLT terminal. Protective Features. The A8936CJT/CLW has a number of protective features incorporated into the design. Under-voltage lockout provides system protection in the event of reduced primary supply voltages. The undervoltage trip point is internally set at approximately 4.3 V. It can be user-defined with an external resistor voltage divider: UVTRIP = 2 (R5 + R 6) R6 (Equation 4) where R5 + R6 << 200 kΩ. Thermal shutdown circuitry is included to protect the device from excessive junction temperature. It is only intended to protect the chip from catastrophic failures due to excessive junction temperature. TM MicroSystems, Inc. (Equation 3) 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 8936 VOICE COIL MOTOR DRIVER TEST CIRCUIT AND TYPICAL APPLICATION +5 V V REF V DD –– I SENSE + – ERROR AMP POWER CONTROL LOGIC PWR OFF ≥ 200 kΩ R I SENSE – RETRACT CONTROL R 7 R8 VDD RS CURRENT-SENSE AMP – V REF 5 R6 BACK EMF FROM SPINDLE MOTOR VOICE COIL MOTOR TSD PROTECTION CIRCUITRY VCC POWER AMP R1 – 2V H GAIN R FAULT + + VREF = 2 V C1 Q S Q R V SENS + WINDOW COMP. V REF VEL FLT Rgm RETRACT V IN CZ + V CC RZ DIODE FOR RETRACT FUNCTION OTHERWISE SHORT TO SUPPLY Dwg. EP-043A 8936 VOICE COIL MOTOR DRIVER A8936CJT Dimensions in Inches (Based on 1 mm = 0.03937”) 48 33 0.0039 ±0.0024 49 32 0.005 0.017 EJECTOR MARK 0.472 BSC 0.394 BSC INDEX MARK 0.0197 BSC 17 64 0.018 0.030 1 0.0035 0.0079 0.050 0.065 16 0.394 BSC 0.472 BSC Dwg. MA-004 in NOTES: 1. This device is similar to JEDEC registration MO-136BJ except for certain tolerances. Contact factory for detailed information. 2. Lead spacing tolerance is non-cumulative. 3. Exact body and lead configuration at vendor’s option within limits shown. 4. The top package body size may be smaller than the bottom package body size by as much as 0.006”. Body dimensions include mold mismatch but do not include mold protrusion. A TM MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 8936 VOICE COIL MOTOR DRIVER A8936CJT Dimensions in Millimeters 48 33 0.10 ±0.06 49 32 0.14 0.27 EJECTOR MARK 12.0 BSC 10.0 BSC INDEX MARK 0.50 BSC 17 64 0.30 0.75 1 0.09 0.20 1.29 1.65 16 10.0 BSC 12.0 BSC Dwg. MA-004 mm NOTES: 1. This device is similar to JEDEC registration MO-136BJ except for certain tolerances. Contact factory for detailed information. 2. Lead spacing tolerance is non-cumulative. 3. Exact body and lead configuration at vendor’s option within limits shown. 4. The top package body size may be smaller than the bottom package body size by as much as 0.15 mm. Body dimensions include mold mismatch but do not include mold protrusion. 8936 VOICE COIL MOTOR DRIVER A8936CLW DIMENSIONS IN INCHES (Based on 1 mm = 0.03937") 28 15 0.0125 0.0091 0.491 0.394 0.2992 0.2914 0.050 0.016 0.020 0.013 2 1 0.050 BSC 3 0.7125 0.6969 0° TO 8° 0.0926 0.1043 0.0040 MIN. Dwg. MA-008-28 in DIMENSIONS 28 IN MILLIMETERS 15 0.32 0.23 10.65 10.00 7.60 7.40 1.27 0.40 0.51 0.33 2 1 1.27 BSC 3 18.10 17.70 0° TO 8° 2.65 2.35 0.010 MIN. 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 design of its products. Components made under military approvals will be in accordance with the approval requirements. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. A Dwg. MA-008-28 mm NOTES: 1. Lead spacing tolerance is non-cumulative. 2. Exact body and lead configuration at vendor’s option within limits shown. TM MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000