Automation and Drives AD SD Standard Drives Lowvoltage

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Automation and Drives A&D SD Standard Drives Low-voltage step-down converters Y Shi Friday, 27

Automation and Drives A&D SD Standard Drives Low-voltage step-down converters Y Shi Friday, 27 October 2006 1

Automation and Drives Existing low-voltage step-down converter A&D SD Standard Drives On-Semi: MC 34063

Automation and Drives Existing low-voltage step-down converter A&D SD Standard Drives On-Semi: MC 34063 J Very low cost: ~£ 0. 09; overall cost: 40 p J Wide operating range: 3~40 V I/P J Adjustable O/P volatge J Up to 1. 5 A with current limiting http: //www. onsemi. com/pub/Collateral/MC 34063 A-D. PDF L Low switching frequency: <100 k. Hz L Bulky & costly LC filtering required L Hysteresis ripple control: minimum ripple required L Low efficiency: ~70%; Bipolar transistor-based switches L No input voltage feed forward: bad line regulation L No internal thermal protection 2

Automation and Drives Improvement for MC 34063 A&D SD Standard Drives Low ripple configuration:

Automation and Drives Improvement for MC 34063 A&D SD Standard Drives Low ripple configuration: J Use ceramic capacitor J R 5 to create enough ripple: ~1 R J If Iout constant, Vout being constant NCP 3063: a higher freq upgrade J Freq operation of 150 k. Hz J Precision 1. 5% reference. (2% of 34063) J New feature: internal thermal shutdown J Samples received J Similar price to MC 34063 http: //www. onsemi. com/pub/Collateral/NCP 3063%20 DATA%20 SHEET. PDF 3

Automation and Drives Existing ST part: L 5970 D A&D SD Standard Drives A

Automation and Drives Existing ST part: L 5970 D A&D SD Standard Drives A 5 E 00775658 Used in PN £ 0. 36 J Wide input range: 4. 4 V to 36 V & adjustable 1. 2~35 V O/P J Up to 1 A O/P current J High efficiency: DMOS switch with 250 m. R Rds(on) J Precision 2% reference. J Fixed freq 250 k. Hz J Voltage feed-forward J Internal current limit and thermal shutdown 4

Automation and Drives TI part: TPS 5420 A&D SD Standard Drives http: //focus. ti.

Automation and Drives TI part: TPS 5420 A&D SD Standard Drives http: //focus. ti. com/lit/ds/symlink/tps 5420. pdf $1. 70 [email protected] K from TI website J Wide input range: 5. 5 V to 36 V J Up to 2 A O/P current (3 A peak) J High efficiency up to 95%: MOS switch with 110 m. R Rds(on) J Precision 1. 5% reference. J Fixed 500 k. Hz switching frequency: downsized & cheaper LC filter design J Input voltage feed forward J Over-current and thermal shutdown J EVM received 5

Automation and Drives NS part: LM 25007 A&D SD Standard Drives http: //www. national.

Automation and Drives NS part: LM 25007 A&D SD Standard Drives http: //www. national. com/pf/LM/LM 25007. html $1. 05 [email protected] K from NS website J Wide input range: 9 V to 42 V J Up to 0. 5 A O/P current J High efficiency: N-Ch MOS switch with 740 m. R Rds(on) J Precision 2% reference. J Up to 800 k. Hz switching frequency: downsized & cheaper LC filter design J Constant ON time control with input voltage feed forward J Current protection and thermal shutdown J Chip and EVM received 6

Automation and Drives Allegro part: ALGA 8498 SLJ-T A&D SD Standard Drives http: //www.

Automation and Drives Allegro part: ALGA 8498 SLJ-T A&D SD Standard Drives http: //www. allegromicro. com/sf/8498/ £ 0. 42 @40 K J Wide input range: 8 V to 50 V & adjustable 0. 8~24 V O/P J Up to 3 A O/P current J High efficiency: DMOS switch with ~500 m. R Rds(on) J Precision 2% reference. J Constant OFF time >100 k. Hz switching frequency J Thermal shutdown 7

Automation and Drives Appendix: Linear step-down converters A&D SD Standard Drives LT 3493 3.

Automation and Drives Appendix: Linear step-down converters A&D SD Standard Drives LT 3493 3. 6 to 36 V input range. 1. 2 A output current. Fixed 750 k. Hz switching frequency. Small cap’s and inductor. Small DFN package. LT 3505 3. 6 to 36 V input range. 1. 2 A output current. Adjustable switching frequency to 3 MHz. Small DFN package. LT 3481 3. 6 to 36 V input range. 2 A output current. Adjustable switching frequency to 2. 8 MHz. Small DFN package. LT 3435 3. 3 to 60 V input range. 2. 4 A output current. Fixed 500 k. Hz switching frequency. TSSOP package. J Excellent performance J Easy to hook up J Small package L Very expensive; normally > $2 8

Automation and Drives Summary A&D SD Standard Drives For performance: J TI-TPS 5420 >

Automation and Drives Summary A&D SD Standard Drives For performance: J TI-TPS 5420 > ST-L 5970 D > NS-LM 25007 > Allegro-A 8498 > NCP 3063 >MC 34063 For O/P current: J A [email protected] A > TPS [email protected] A > NCP [email protected] 5 A = MC [email protected] 5 A >L 5970 [email protected] A > LM [email protected] 5 A For the single chip cost: J MC 34063 > NCP 3063 > L 5970 D > A 8498 > LM 25007 > TPS 5420 For the overall converter cost: J NCP 3063 > MC 34063 > LM 25007 > A 8498 > L 5970 D > TPS 5420 For performance-to-cost: J TPS 5420 > L 5970 D > LM 25007 > NCP 3063 > MC 34063 > A 8498 9