MIC49150 Evaluation Board 1.5A Low Voltage LDO Regulator By Martin Galinski General Description The demonstration board can be used to evaluate the MIC49150. The MIC49150, a 1.5 amp, ultra-high speed, low dropout linear regulator, utilizes a split supply input to regulate low output voltages. It is offered in two packages, a low profile S-pack and 8pin power MSOP. The MIC49150 is also offered in fixed and adjustable outputs. Fixed output versions add enable pin functionality, allowing it to be placed in a zero-current off mode state. The adjustable version allows for the use of a resistor divider network to adjust for the desired output voltage. The evaluation board accommodates the adjustable version. Requirements The MIC49150 requires two power supplies. One to provide a minimum of 1.5A to the VIN and the other to provide VBIAS current. Although typical VBIAS current is 45mA, in dropout conditions VBIAS currents can reach as high as 270mA. The VBIAS supply should be able to supply a minimum of 300mA. The VBIAS should be able to deliver a minimum of 3v or 2.1V greater than Vout, whichever is greater. In cases where the VIN voltage satisfies the minimum VBIAS voltage, one supply can be used. Circuit Description The MIC49150 ultra-high speed regulator is easy to use. It is extremely tolerable to a wide range and types of output capacitor. Although there is no minimum output capacitor requirement for the MIC49150, a minimum 1µ F capacitor is recommended. device. This is the minimum recommended distance from the device that the capacitor should be placed. The evaluation board has a 10µF ceramic on the Vin pin. Although this is much larger than required for the device, this was designed to allow for the long inductive test leads that will be attached to the evaluation board. The output can be selected by using the evaluation board jumper. The available output options on the evaluation board are 1.0V, 1.2V, 1.5V and 1.8V. Also, a 0.9V output can be obtained by removing the jumper altogether. Any of the 4 bottom feedback resistors can be substituted to obtain a different output voltage. The equation to set the output is as follows: R1 VOUT = VREF + 1 R2 VREF = 0.9 R1 on the evaluation board is set to 1K. Due to the high bandwidth of the MIC49150, larger values of R1 and the parasitic capacitance of the feedback pin introduce an additional pole. For R1 values greater than 1K, a small feed forward capacitor across R1 will be required to maintain stability. Since R1 on the evaluation board is set to 1K, the formula for adjusting the output to the desired level is as follows: V R2 = REF VREF R1 VOUT 0.9V R2 = 0.9V 1k VOUT An input capacitor is required when the power supply is more than 4” away from the device. All evaluation boards include an input capacitor within 1” of the September 2004 M9999-090104 (408) 955-1690 Micrel MIC49150 Evaluation Board U1 MIC49150BR 2 J1 +VBIAS 3.0V to 6.5V 1 J2 +VIN 1.4V to 6.5V max 1 C1 1µF 10V VBIAS 4 VOUT VIN ADJ 5 1 C3 1µF 10V 1 R1 1k GND R2 8k 3 C2 10µF 10V J3 GND R3 R4 2.87k 1.5k A B JP1 A = 1.0VO B = 1.2VO C = 1.5VO D = 1.8VO JP1 HEADER 4X2 R5 1k C D 2 4 6 8 1 3 5 7 1 1 GND J4 VOUT GND J5 GND MIC49150BR Circuit Bill of Material MIC49150BR Evaluation Board Item C1, C3 Part Number GRM40 XR5 105K 10 Manufacturer muRata(1) Description 0.1µF, 10V capacitor Qty. 2 C2 GRM235Y5V106Z10 muRata(1) R1, R5 CRCW08051001FRT1 10µF, 10V capacitor 1 Vishay Dale(4) 1k, 1%, 1/10W, 0805 resistor 2 Dale(4) 8.87k, 1%, 1/10W 0805 resistor 1 2.87k, 1%, 1/10W 0805 resistor 1 1.5k, 1%, 1/10W 0805 resistor 1 Programmable current limit µCap LDO 1 R2 CRCW08058871FRT1 Vishay R3 CRCW08052871FRT1 Vishay Dale(4) R4 CRCW08051501FRT1 Vishay Dale(4) U1 MIC49150BR Or MIC49150BMM Micrel, Inc. (5) Notes: 1. muRata: www.murata.com 2. Vishay Dale: www.vishay.com 3. Micrel, Inc.: www.micrel.com MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2004 Micrel, Incorporated. September 2004 2 M9999-090104 (408) 955-1690