Allegro MicroSystems, Inc. · NASDAQ:ALGM
Allegro MicroSystems — Technical Presentation (2006)
20 slides from Allegro MicroSystems's technical presentation, 2006
Slide 1: A8698 and A8697: 25 V Input, 3 or 4 Amp Output Step-Down Regulators
A8698 and A8697: 25 V Input, 3 or 4 Amp Output High-Performance Power ICs and Hall-Effect Sensors Step-Down Regulators Power Management Business Unit 2006 Confidential C1ONCEP1T DRIVEN December,2003 2006
Slide 2: A8698 – Wide Input Voltage 3.0A Step Down Regulator
A8698 – Wide Input Voltage 3.0A Step Down Regulator Contacts: Nina Tjoa --- Tactical Marketing Sophie Chen --- System Engineer Mark Gaboriault --- Marketing Manager Datasheets are on the Allegro Website Confidential C2ONCEP2T DRIVEN December,2003 2006
Slide 3: What are the products?
What are the products? • The A8698 and A8697 are constant off-time current mode step-down regulators with a wide input voltage range. • Regulation voltage is set by external resistors, to output voltages as low as 0.8 V. • Integrated power DMOS switch to reduce the total solution footprint. • The A8
Slide 4: Target Markets and Applications
Target Markets and Applications Applications with 8-25 V input voltage range needing a buck regulator for up to 3A or 4A output current. For example: • Consumer equipment power • Networking equipment power • 12 V lighter-powered applications (portable DVD, etc) • Point of Sale (POS) applications • S
Slide 5: Features
Features • 8-25V Input Voltage Range • Integrated DMOS Switch ---- 180 mOhm Rdson • Adjustable Fixed off-time ---- External R sets up Toff • Adjustable output voltage down to 0.8V, set by voltage divider • Pulse skipping mode at light load for higher efficiency • High efficiency curve across output
Slide 6: Block Diagram
Block Diagram Confidential C6ONCEP6T DRIVEN December,2003 2006
Slide 7: Toff and Frequency Setup
Toff and Frequency Setup • Toff time is setup by external resistor Rset (1 − 0.03Vbias ) Toff = 12 × 109 (Vout + V f + I out ⋅ R L ) ⋅ Toff Ton = (Vin − I out ⋅ RDSON − I out ⋅ R L − Vout ) 1 f sw = Ton + Toff Confidential C7ONCEP7T DRIVEN December,2003 2006
Slide 8: Advanced Short Circuit Protection
Advanced Short Circuit Protection • Current limit of the Buck switch : 3.5 when VFB>0.4V. 1.15A when VFB< 0.4V. • 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 < 0.16 8 x Toff < 0.32 4 x Toff < 0.5 2 x Toff >0.5 To
Slide 9: 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 Confidential C9ONCEP9T DRIVEN Decemb
Slide 10: Typical Application Circuit ---- EVB
Typical Application Circuit ---- EVB Bootstrap capacitor Vin25V Vin 8V to 24V C1 X2 C2 82uF/35V Input Capacitor 0.1uF C3 0.01uF Inductor 33uH Vout BOOT Vin 3.3V/3.0A ENB LX A8698 Output Capacitor TSET Vbias C4 R3 GND 330 uF/6.3V 30. 1K FB (Aluminum ) R1 R2 6.34K 2K D1 B340 Setup off time Voltage div
Slide 11: Typical Application Circuit ---- EVB Layout
Typical Application Circuit ---- EVB Layout Top & silkscreen Bottom Confidential C11ONCEP11T DRIVEN December,2003 2006
Slide 12: Performance ---- Efficiency
Performance ---- Efficiency Efficiency is as high as 91%. Confidential C12ONCEP12T DRIVEN December,2003 2006
Slide 13: Performance ---- Ripple & Switching Waveform
Performance ---- Ripple & Switching Waveform Confidential C13ONCEP13T DRIVEN December,2003 2006
Slide 14: Performance ---- Start-up & Power Off
Performance ---- Start-up & Power Off Confidential C14ONCEP14T DRIVEN December,2003 2006
Slide 15: Performance ---- Transient Response
Performance ---- Transient Response Confidential C15ONCEP15T DRIVEN December,2003 2006
Slide 16: Performance ---- Load & Line Regulation
Performance ---- Load & Line Regulation Confidential C16ONCEP16T DRIVEN December,2003 2006
Slide 17: Low ESR Capacitor Application
Low ESR Capacitor Application Low ESR capacitor (SP, POSCAP) can be used with RC ripple injection Confidential C17ONCEP17T DRIVEN December,2003 2006
Slide 18: A8697 – Wide Input Voltage 4.0A Step Down Regulator
A8697 – Wide Input Voltage 4.0A Step Down Regulator Higher current limit version of A8698 Confidential C18ONCEP18T DRIVEN December,2003 2006
Slide 19: A8697 ---- Maximum Load Current Derating w/ Iout
A8697 ---- Maximum Load Current Derating w/ Iout Confidential C19ONCEP19T DRIVEN December,2003 2006
Slide 20: Sales Information
Sales Information Full P/Ns: A8698ELJTR-T & A8697ELJTR-T Pb-Free, Tape/reel A8698ELJ-T & A8697ELJ-T Pb-Free, Tubes Standard pack: 3,000pcs per Reel, 98 pcs per Tube Samples and Evaluation Boards Available Confidential C20ONCEP20T DRIVEN December,2003 2006