Allegro Microsystems, Inc. · NASDAQ:ALGM

Allegro Microsystems — Technical Presentation (November 2007)

16 slides from Allegro Microsystems's technical presentation, November 2007

  1. Slide 1: A8498/99: 50V-Capable Step-Down Regulators

    A8498/99: 50V-Capable Step-Down Regulators

  2. Slide 2: What are the products?

    What are the products? • 1.5A (A8499) and 3A (A8498) step-down regulators that will handle a wide range of input voltages up to 50V • A8499/98 differences include output current (1.5/3A), feedback voltage (1.2/0.8V), and Rdson (lower for A8498) • Both are fixed off-time current-mode-controlled buck

  3. Slide 3: Target Markets and Applications

    Target Markets and Applications • Applications with 8-50V input voltage range needing buck regulator for 1.5A (A8499) or 3.0A (A8498) output current. • Consumer equipment power • Uninterruptible Power Supplies (lead acid battery charger) • Automotive Telematics - 9 to 16V input, with higher voltage

  4. Slide 4: Features and Benefits

    Features and Benefits 8-50 V input range √ Very wide input voltage range Integrated DMOS switch √ No external FET needed Adjustable fixed off-time √ User adjustability Adjustable output:1.2-24V (A8499) or 0.8-24V (A8498) √ User adjustability

  5. Slide 5: Features and Benefits

    Features and Benefits Flat efficiency curve across output current √ Minimal change in efficiency across wide operating range 1.5 or 3.0 Amp output in standard SOIC-8 package √ Output current capability in small package with integrated FET Low shutdown current √ Maximized battery life and low power d

  6. Slide 6: 50V rating helps for Automotive Load Dump

    50V rating helps for Automotive Load Dump ISO 7637-2 load dump transient - occurring in the event of a discharged battery being disconnected while the alternator is generating charging current and with other loads remaining on the alternator circuit at this moment; the load dump amplitude depends on

  7. Slide 7: Block Diagram

    Boot Charge & m Zz a Switch PWM Control met 34H Hos 4 | Peak fal o IW ---4--- 4 ------- a —---~---------0---~ < o > VBIAS is connected to VOUT when Vour target is between 3.3 and5V Soft Start Ramp Generation 4H" L---~~<

  8. Slide 8: Typical Application Circuit (A8499)

    Typical Application Circuit (A8499) Bootstrap capacitor Vin 12V C2 C1 22uF/25V Input Capacitor 0.1uF C3 0.01uF Inductor 47uH Vout BOOT Vin 5.0V/1.8A ENB LX A8499 Output Capacitor TSET Vbias C4 R3 330 uF/6.3V GND FB 30. 1K (Aluminum ) R1 R2 10K 3. 16K D1 B340 Setup off time Voltage divider Use Vout a

  9. Slide 9: Toff and Frequency Setup

    Toff and Frequency Setup • Toff time is setup by external resistor R(Tset) v.s. Toff (µs) 17 Rset 15 Toff = 12 × 109 13 11 Toff (µs) 9 (Vout + V f + I out ⋅ R L ) ⋅ Toff 7 Ton = (Vin − I out ⋅ RDSON − I out ⋅ R L − Vout ) 5 3 1 1 f sw = 12 36 60 84 108 132 156 180 Ton + Toff Resistance (kΩ) 9

  10. Slide 10: Optional Vbias Connection

    Optional Vbias Connection • Bias circuitry runs off Vin supply during start up. • Improved overall system efficiency by running Vbias off Vout (3.3~5.0V) during normal operation. • Connect Vbias to external voltage source. • No sequencing needed for normal operation.

  11. Slide 11: Advanced Short Circuit Protection

    Advanced Short Circuit Protection • Current limit of the Buck switch: 2.2A when VFB>0.5V. 0.8A when VFB< 0.5V. • Toff is extended for low Vout at power up and in case of short to prevent loss of control of current limit. VFB (V) TSET Multiplier < 0.25 8 x Toff < 0.50 4 x Toff < 0.75 2 x Toff >0.75 T

  12. Slide 12: EVB Layout

    EVB Layout High Voltage Input Capacitor Output Capacitor Placeholder Placeholder

  13. Slide 13: Performance - Ripple & Switching Waveform

    Performance - Ripple & Switching Waveform Ch1: Switch node @ 10V/div Ch3: Output ripple @ 500mV/div Ch4: Output ripple @ 10mV/div (a) Vin=20V (b) Vin=12V Vout=5.0V Iout=1.8A

  14. Slide 14: Competitive Landscape

    Competitive Landscape • Medium voltage buck regulators from National, ST Microelectronics, Linear Tech, Monolithic Power Systems, and Anachip – LM5007/8, LM257x, LM259xx – L497x, L597x – LT107x, LT343x – MPS159x, MPS235x, MP236x – AP1501/6/7 • Allegro has smaller package and more cost effective solu

  15. Slide 15: Competitive Advantages

    Competitive Advantages • 8-50 V input range • Integrated DMOS switch • Flat efficiency curve across output current • 1.5 or 3.0A output in standard SOIC-8 package • Low shutdown current • Low cost

  16. Slide 16: Sales Information

    Sales Information – Full part numbers: A8499SLJTR-T and A8498SLJTR-T Pb-Free on tape/reel – Standard pack – 3,000pcs per reel – Lead-time: 10-12 wks ARO – Samples Available – Contact Factory for Evaluation Boards (will be in online store)

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