Demo Circuit DC136A: LT1575 UltraFast Linear Regulator for Microprocessor Power
Design guide for the DC136A demo circuit featuring the LT1575 linear regulator controller, optimized for high-speed microprocessor power and fast transient response.
Overview
The DC136A is a demonstration circuit manual for the LT1575, an ultra-high-speed linear regulator controller designed to meet the tight voltage tolerances and extreme dynamic loading requirements of high-performance microprocessors like the Intel Pentium. By driving an external power MOSFET, the circuit achieves a 1MHz loop crossover frequency and a 370ns response time to 5A load steps, allowing for the elimination of large bulk electrolytic capacitors. The demo board includes a Pentium-compatible socket for use with an Intel Power Validator, an onboard load pulse generator for evaluation, and jumper-selectable output voltages of 2.8V, 3.3V, and 3.5V. The document provides detailed layout recommendations for minimizing parasitic inductance and thermal management guidelines for the MOSFET pass transistor.
Use Cases
- Powering high-performance CPUs with extreme dynamic loading
- Reducing component count and bulk capacitors in power delivery networks
- Evaluating ultra-fast transient response in linear regulators
- Designing low-ESL PCB layouts for high-speed power applications
Topics
Referenced Parts
AVX
C3-C26, C31, C40, C41, C45 27 0805ZC105KAT3S 1μF 16V 20% X7R Chip Capacitor AVX (803) 946-0362
115200
Aavid
1 115200 Kool-Klip Aavid (714) 556-2665
533402/22
Aavid
H1 1 533402/22 Heat Sink Aavid (714) 556-2665
3801S-2-G1
Comm Con
JP1, JP2 2 3801S-2-G1 0.100 1 × 2 Header Comm Con (818) 301-4200
CCIJ230-G
Comm Con
2 CCIJ230-G Shunt Comm Con (818) 301-4200
112404
Connex
J3 1 112404 Vertical BNC PC-Mount Connector Connex (805) 378-6464
LT1575CS8
Linear Technology
U1 1 LT1575 UltraFast Linear Regulator Controller LTC (408) 432-1900
214 320 3110
Methode Electronics
U3 1 214 320 3110 PGA 320 Pin ZIF Socket Methode (800) 323-6864
2502-02
Mill-Max
E9 1 2502-02 Turret Terminal Mill-Max (516) 922-6000
CR10-1211F-T
TAD
R19 1 CR10-1211F-T 1.21k 1/10W 1% Chip Resistor TAD (800) 508-1521
CR10-1581F-T
TAD
R22 1 CR10-1581F-T 1.58k 1/10W 1% Chip Resistor TAD (800) 508-1521
CR10-2671F-T
TAD
R21 1 CR10-2671F-T 2.67k 1/10W 1% Chip Resistor TAD (800) 508-1521
CR10-3741F-T
TAD
R20 1 CR10-3741F-T 3.74k 1/10W 1% Chip Resistor TAD (800) 508-1521
CR10-4R75F-T
TAD
R36 1 CR10-4R75F-T 4.75Ω 1/0W 1% Chip Resistor TAD (800) 508-1521
CR10-511J-T
TAD
R12 1 CR10-511J-T 51.1Ω 1/10W 1% Chip Resistor TAD (800) 508-1521
CR10-622J-T
TAD
R35 1 CR10-622J-T 6.2k 1/10W 1% Chip Resistor TAD (800) 508-1521
2N7002
Generic
Q9 2N7002 Q10 2N7002 Q8 2N7002 Q4 2N7002 Q2 2N7002 Q7 2N7002
TLC555C
Texas Instruments
U2 TLC555C timer is configured as a low frequency oscillator
S16954
Vishay Siliconix
Q15B S16954 Q17A S16954 Q17B S16954 Q15A S16954
TP0610T
Vishay Siliconix
Q14 TP0610T Q3 TP0610T Q1 TP0610T Q6 TP0610T Q13 TP0610T Q12 TP0610T Q11 TPO610T Q16 TP0610T
| IRFZ24 | International Rectifier | Q6 1 IRFZ24 Power MOSFET IR (310) 322-3331 |
| 6SA330M | Sanyo | C32, C33 2 6SA330M, K 330μF 6.3V 20% OS-CON Electrolytic Capacitor Sanyo (619) 661-1055 |
| 08051A100MAT3S | AVX | C39 1 08051A100MAT3S 10pF 100V 20% NPO Chip Capacitor AVX (803) 946-0362 |
| 08053E223MAT3S | AVX | C35 1 08053E223MAT3S 0.22μF 50V 20% Chip Capacitor AVX (803) 946-0362 |
| 08055A102MAT3S | AVX | C34 1 08055A102MAT3S 1000pF 50V 20% NPO Chip Capacitor AVX (803) 946-0362 |
| 0805ZC105KAT3S | AVX | C3-C26, C31, C40, C41, C45 27 0805ZC105KAT3S 1μF 16V 20% X7R Chip Capacitor AVX (803) 946-0362 |
| 115200 | Aavid | 1 115200 Kool-Klip Aavid (714) 556-2665 |
| 533402/22 | Aavid | H1 1 533402/22 Heat Sink Aavid (714) 556-2665 |
| 3801S-2-G1 | Comm Con | JP1, JP2 2 3801S-2-G1 0.100 1 × 2 Header Comm Con (818) 301-4200 |
| CCIJ230-G | Comm Con | 2 CCIJ230-G Shunt Comm Con (818) 301-4200 |
| 112404 | Connex | J3 1 112404 Vertical BNC PC-Mount Connector Connex (805) 378-6464 |
| LT1575CS8 | Linear Technology | U1 1 LT1575 UltraFast Linear Regulator Controller LTC (408) 432-1900 |
| 214 320 3110 | Methode Electronics | U3 1 214 320 3110 PGA 320 Pin ZIF Socket Methode (800) 323-6864 |
| 2502-02 | Mill-Max | E9 1 2502-02 Turret Terminal Mill-Max (516) 922-6000 |
| CR10-1211F-T | TAD | R19 1 CR10-1211F-T 1.21k 1/10W 1% Chip Resistor TAD (800) 508-1521 |
| CR10-1581F-T | TAD | R22 1 CR10-1581F-T 1.58k 1/10W 1% Chip Resistor TAD (800) 508-1521 |
| CR10-2671F-T | TAD | R21 1 CR10-2671F-T 2.67k 1/10W 1% Chip Resistor TAD (800) 508-1521 |
| CR10-3741F-T | TAD | R20 1 CR10-3741F-T 3.74k 1/10W 1% Chip Resistor TAD (800) 508-1521 |
| CR10-4R75F-T | TAD | R36 1 CR10-4R75F-T 4.75Ω 1/0W 1% Chip Resistor TAD (800) 508-1521 |
| CR10-511J-T | TAD | R12 1 CR10-511J-T 51.1Ω 1/10W 1% Chip Resistor TAD (800) 508-1521 |
| CR10-622J-T | TAD | R35 1 CR10-622J-T 6.2k 1/10W 1% Chip Resistor TAD (800) 508-1521 |
| 2N7002 | Generic | Q9 2N7002 Q10 2N7002 Q8 2N7002 Q4 2N7002 Q2 2N7002 Q7 2N7002 |
| TLC555C | Texas Instruments | U2 TLC555C timer is configured as a low frequency oscillator |
| S16954 | Vishay Siliconix | Q15B S16954 Q17A S16954 Q17B S16954 Q15A S16954 |
| TP0610T | Vishay Siliconix | Q14 TP0610T Q3 TP0610T Q1 TP0610T Q6 TP0610T Q13 TP0610T Q12 TP0610T Q11 TPO610T Q16 TP0610T |