MIC37302 Evaluation Board Micrel MIC37302 LDO Point-of-Load Evaluation Board Advance Information General Description Features The MIC37302 LDO module is capable of producing regulated output voltage down to 1.25V from an input supply of 5.5V maximum. Main applications include 3.3V to 2.5V and 2.5V to 1.8V at up to 3A load current from a small footprint board requiring minimal exterior components. The information contained within this document includes schematic, safe operating area (SOA) curve and output voltage trim details. Output Voltage Setting The factory set output voltage setting is 2.5V. A bill of materials for 1.8V and 3.3V is also included. To set a different output voltage, please use the following equation: • • • • • • Operates with single 2.25V to 5V input voltage Output current 3A (3W dissipation max.) Small size (1.05 × 0.63 × 0.3) No additional capacitors needed Remote sense and remote on/off Output voltage adjustable down to 1.25V Point-of-Load Evaluation Board R3 + R4 VOUT = 1.24V 1+ R5 Evaluation Board Schematic U1 MIC37302BR R1 10k C1 10µF, 16V 2 IN 1 EN OUT 4 ADJ GND 5 R2 1Ω R3 154Ω 3 R4 154Ω C2 22µF 6.3V J1 1 2 3 4 5 6 7 8 9 10 R5 Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com December 2002 1 MIC37302 MIC37302 Evaluation Board Micrel Pin Description Specifications Pin Number Function Input: +2.25V to +5.0V 1 GND Output: 1.8V, 2.5V, 3.3V 2 SENSE Dropout Voltage 500mV Max. 3 TRIM Tolerance ±1% 4 ENABLE Output Current 3A 5 VIN Load Regulaton ±0.5% 6 VIN Line Regulation ±0.2% 7 GND Isolation Non-isolated 8 GND Air Flow 200LFM 9 VOUT Remote On/Off 10 VOUT Open/High On Low Off Trimming MAXIMUM POWER DISSIPATION ( PD ) Trimming Down When the output voltage needs to be lowered, use a resistor from the Trim pin to VOUT pin. The trim resistor will be in parallel with R3 and R2. To calculate the value for Rtrim when the output voltage needs to be trimmed down use the following term. (46.35k(Vnew) − 86.89k) R trim (Ω) = (755.2 − 301(Vnew) The lowest value achievable using this method is 1.87V (trim resistor value is zero Ohm). Trimming UP When the output voltage needs to be higher, use a resistor from Trim pin to GND. Caution! If this Trim pin is shorted to ground, the output voltage will be equal to input voltage. R trim_u (Ω) = MIC37302 Point-of-Load Thermal SOA 7 6 5 200LFM 4 3 2 1 0LFM 0 0 20 40 60 80 100 120 TEMPERATURE (°C ) Safe Operating Area (131.3k) (455 (Vnew) – 1.141k) 2 December 2002 MIC37302 Evaluation Board Micrel PCB Layout December 2002 Silk Screen Top Silk Screen Bottom Top Layer Bottom Layer 3 MIC37302 MIC37302 Evaluation Board Micrel Bill of Materials 1.8VOUT Item Part Number Manufacturer C1 C3225X5R1C106MT TDK(1) 10µF, 16V Ceramic Capacitor 1 C2 C3225X5R0J226KT TDK 22µF, 6.3V Ceramic Capacitor 1 J1 929835-01-10 3M(2) 10-Pin Right Angle Connector 1 R1 CRCW0805103F Vishay(3) 10k, 1%, Size 0805 Resistor 1 R2 CRCW08051R00F Vishay 1Ω, 1%, Size 0805 Resistor 1 R3, R4 CRCW08051540F Vishay 154Ω, 1%, Size 0805 Resistor 2 R5 CRCW08056980F Vishay 698Ω, 1%, Size 0805 Resistor 1 3A Linear Regulator 1 U1 Description Semiconductor(4) Qty. MIC37302BR Micrel Part Number Manufacturer C1 C3225X5R1C106MT TDK(1) 10µF, 16V Ceramic Capacitor 1 C2 C3225X5R0J226KT TDK 22µF, 6.3V Ceramic Capacitor 1 J1 929835-01-10 3M(2) 10-Pin Right Angle Connector 1 R1 CRCW0805103F Vishay(3) 10k, 1%, Size 0805 Resistor 1 R2 CRCW08051R00F Vishay 1Ω, 1%, Size 0805 Resistor 1 R3, R4 CRCW08051540F Vishay 154Ω, 1%, Size 0805 Resistor 2 R5 CRCW08053010F Vishay 301Ω, 1%, Size 0805 Resistor 1 3A Linear Regulator 1 2.5VOUT Item U1 Description Semiconductor(4) Qty. MIC37302BR Micrel Part Number Manufacturer C1 C3225X5R1C106MT TDK(1) 10µF, 16V Ceramic Capacitor 1 C2 C3225X5R0J226KT TDK 22µF, 6.3V Ceramic Capacitor 1 J1 929835-01-10 3M(2) 10-Pin Right Angle Connector 1 R1 CRCW0805103F Vishay(3) 10k, 1%, Size 0805 Resistor 1 R2 CRCW08051R00F Vishay 1Ω, 1%, Size 0805 Resistor 1 R3, R4 CRCW08051540F Vishay 154Ω, 1%, Size 0805 Resistor 2 R5 CRCW08051870F Vishay 187Ω, 1%, Size 0805 Resistor 1 3A Linear Regulator 1 3.3VOUT Item U1 MIC37302BR Micrel Note 1. TDK tel: 408-392-1400 Note 2. 3M tel: 1-888-364-3577 Note 3. Vishay tel:402-644-4218 Note 4. Micrel Semiconductor tel: 408-944-0800 Description Semiconductor(4) MICREL, INC. 1849 FORTUNE DRIVE TEL + 1 (408) 944-0800 FAX SAN JOSE, CA 95131 + 1 (408) 944-0970 WEB Qty. USA http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2002 Micrel, Incorporated. MIC37302 4 December 2002