A4934GLPTR-T

A4934 Three-Phase Sensorless Fan Driver Discontinued Product This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available. Date of status change: October 31, 2011 Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the A4941. NOTE: For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. 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. A4934 Three-Phase Sensorless Fan Driver Features and Benefits Description • Sensorless (no Hall sensors required) • Soft switching for reduced audible noise • Minimal external components • PWM speed input • FG speed output • Low power standby mode • Lock detection • Optional overcurrent protection The A4934 three-phase motor driver incorporates BEMF sensing to eliminate the requirement for Hall sensors in fan applications. A pulse wave modulated (PWM) input is provided to control motor speed, allowing system cost savings by eliminating external variable power supply. PWM input can also be used as an on/off switch to disable motor operation and place the IC into a low power standby mode. The A4934 soft switching settings are designed for lower inductance or lower speed motors. For higher inductance or higher speed motors consider using the pin-compatible A4941. Package: 16-pin TSSOP with exposed thermal pad (suffix LP) The A4934 is provided in a 16-pin TSSOP package (suffix LP) with an exposed thermal pad. It is lead (Pb) free, with 100% matte tin leadframe plating. Not to scale Functional Block Diagram 12 V 0.1 μF VCP 0.1 μF CP1 VBB CP2 Charge Pump 10 μF +VINT OUTA SLEW Soft Switch PWM Control Logic 3-Phase Half Bridges OUTB M OUTC 25 kHz OSC SENSE OCP Timers VBB O/C 0.18 Ω FC TEST 10 kΩ FG Sequencer (Direction) Startup OSC CDCOM GND Adaptive Commutation Delay CTAP BEMF Comp FCOM OUTA OUTB OUTC A4934-DS GND A4934 Three-Phase Sensorless Fan Driver Selection Guide Part Number Packing A4934GLPTR-T 4000 pieces per 13-in. reel Absolute Maximum Ratings Characteristic Symbol Supply Voltage VBB Logic Input Voltage Range VIN Logic Output Voltage VOUT Output Current IOUT Rating Unit 20 V PWM, SLEW –0.3 to 5.5 V FC –0.3 to VBB V FG VBB V Peak (startup and lock rotor) 1.25 A 800 mA –40 to 105 ºC TJ(max) 150 ºC Tstg –55 to 150 ºC Min. Typ. Max. Unit 8 – 16 V Operating Ambient Temperature TA Maximum Junction Temperature Storage Temperature Notes Duty cycle = 100% G temperature range Recommended Operating Conditions Characteristic Symbol Supply Voltage VBB Output Current IOUT Conditions Peak (startup and lock rotor) – – 800 mA Run current – 1.5 A rated D2 17 V R1 0.18 Ω / 0.25 W D2 VBB Typical Application Circuit; speed adjusted via VBB Startup Oscillator Setting (FC) Typically, the 50 ms setting is optimum for motors appropriate for use with the A4934. If the motor does not produce a proper BEMF signal at startup when power is applied, a longer setting may be required. SLEW Setting For some motors, soft switching will reduce audible noise. The soft switching function can result in motor stall for some motors, specifically motors with large inductance that run at higher speeds. For this situation, there are two potential solutions: • Limit the motor speed by lowering the maximum demand, by reducing either Vmotor(max) or the PWM duty applied. • Consider the pin-to-pin compatible IC A4941 that allows disabling of the soft switching function. Current Limiting Use of the current limit circuit is not required. If motor resistance (phase-to-phase) will limit the current below the rating in the Absolute Maximum table, then simply connect the SENSE pin to Description VBB supply capacitor, minimum 10 μF, electrolytic can be used Charge pump ceramic capacitors FG pull-up resistor, can be pulled-up to VBB if required Optional blocking diode for supply reverse polarity protection Transient voltage suppressor (TVS) Current limiting sense resistor, required for low resistance motors ground. That is: • If (VBB(max) / Rmotor ) < 1.25 A, eliminate RS. • If (VBB(max) / Rmotor ) > IOUT (max), the choice of RS determines the current limit setting; recommended range is 167 mΩ < RS < 250 mΩ. Note: For some motor types, use of the current limit circuit may prevent proper startup due to the effect of the chopping on the BEMF voltage appearing on the tri-stated winding. Layout Notes • Connect GND pins (5,11) to exposed pad ground area under package. • Add thermal vias from exposed pad to bottom side ground plane. • Place VBB decoupling capacitor as close to the IC as possible. • Place sense resistor, (if used), as close to the IC as possible. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 A4934 Three-Phase Sensorless Fan Driver Package LP, 16-Pin TSSOP with Exposed Thermal Pad 0.45 5.00±0.10 16 0.65 16 8º 0º 0.20 0.09 1.70 B 3 NOM 4.40±0.10 3.00 6.40±0.20 6.10 0.60 ±0.15 A 1 1.00 REF 2 3 NOM 0.25 BSC Branded Face 16X SEATING PLANE 0.10 C 0.30 0.19 C 3.00 C PCB Layout Reference View For Reference Only; not for tooling use (reference MO-153 ABT) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown 1.20 MAX 0.65 BSC 1 2 SEATING PLANE GAUGE PLANE 0.15 0.00 A Terminal #1 mark area B Exposed thermal pad (bottom surface); dimensions may vary with device C Reference land pattern layout (reference IPC7351 SOP65P640X110-17M); All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances; when mounting on a multilayer PCB, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5) Copyright ©2010, Allegro MicroSystems, Inc. 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 8