MIC5325 Evaluation Board Low VIN/VOUT 400mA ULDO™ with Ultra-Low IQ General Description The MIC5325 is a high performance, µCap low dropout regulator, offering ultra-low operating current while maintaining very fast transient response. The MIC5325 can source up to 400mA of output current and can regulate down from a low input supply voltage to increase system efficiency. Ideal for battery operated applications; the MIC5325 offers extremely low dropout voltage 110mV typically @ 400mA, and low ground current at all load conditions (typically 35µA). The MIC5325 can also be put into a zero-off-mode current state, drawing virtually no current when disabled. The MIC5325 is available in fixed output voltages in the tiny 6-pin 2mm x 2mm thin MLF® leadless package. Requirements The MIC5325 evaluation board requires two power supplies. The first supply must be able to provide a minimum of 400mA with a voltage range of 1.7V to 5.5V to the VIN. The second supply is required to provide the VBIAS current. Although typical VBIAS current is 40uA in dropout conditions VBIAS current can reach as high as 250mA. VBIAS supply should be able to deliver a minimum of 300mA with a voltage range of 2.5V to 5.5V. The output load can be either an active or passive load. Precautions The evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN terminal may damage the device. Getting Started 1. Connect an external supply to VBIAS. Apply desired voltage to VBIAS (J1) and ground terminal (J2), paying careful attention to polarity and supply voltage (2.5V ≤ VBIAS ≤ 5.5V). An ammeter may be placed between the Bias supply and VBIAS terminal to the evaluation board. The evaluation board has a 1µF capacitor connected from VBIAS (J1) pin to GND (J2). 2. Connect an external supply to VIN. Apply desired input voltage to the VIN (J3) and ground terminal (J2) of the evaluation board, paying careful attention to polarity and supply voltage (1.7V ≤ VIN ≤ VBIAS). An ammeter may be placed between the input supply and the VIN terminal to the evaluation board. Ammeter and/or power lead resistance can reduce the voltage supplied to the input. Ensure that the supply voltage is monitored at the VIN terminal. There is 1µF capacitor connected from VIN (J3) to GND (J2). 3. Enable/Disable the MIC5325. The evaluation board is provided with 10k pull up resistors on enable pin (EN) to VIN. To disable an output, simply jumper the EN terminal (J6) to the GND terminal (J2).The enable pin must be either pulled high or low. Removing the pull up resistors and leaving the pins floating will cause the regulators to operate in an indeterminate state. 4. Connect the loads to the VOUT terminal (J4) and ground terminal (J5). The load can be either a passive (resistor) or active (electronic load). Be sure to monitor the output voltage at the VOUT (J4) terminals. The evaluation board has a 1µF capacitor connected from VOUT (J4) to GND (J5). 5. Bypass Pin. The evaluation board provides 10nF capacitor connected from Bypass pin to GND (J2) to reduce the output voltage noise. The capacitor bypasses the internal reference. The bypass capacitor can be increased, further reducing noise and improving PSRR. Turn-on time increases slightly with respect to bypass capacitance. A unique, quick-start circuit allows the MIC5325 to drive a large capacitor on the bypass pin without significantly slowing turn-on time. ULDO is a trademark of Micrel, Inc. MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com March 2008 M9999-030308-A Micrel, Inc. MIC5325 Evaluation Board Ordering Information Part Number Description MIC5325-XXYMT EV Evaluation board with the 400mA ULDO™ device Evaluation Board Schematic U1 MIC5325-xxYMT VBIAS J1 VBIAS 1 VBIAS VOUT VIN BYP VOUT J4 VOUT 4 C1 1µF/6.3V J3 VIN 3 R3 10k J6 EN 6 C4 1µF/6.3V C3 10nF/10V EN GND C2 1µF/6.3V 5 2 J5 GND J2 GND Bill of Materials Item Part Number Manufacturer C1, C2, C4 C1608X5R0J105K TDK(1) C3 VJ0603Y104KXXAT R3 CRCW06031002FKEYE3 U1 MIC5325-XXYMT Description Qty Capacitor, 1µF Ceramic, 6.3V, X5R, Size 0603 3 (2) Capacitor, 0.1µF Ceramic, 10V, X7R, Size 0603 1 (2) Vishay Resistor, 10kΩ, 1%, 1/16W, Size 0603 1 Micrel(3) UCAP LDO, 400mA, 2mm x 2mm Thin MLF® 1 Vishay Notes: 1. TDK: www.tdk.com 2. Vishay: www.vishay.com 3. Micrel, Inc.: www.micrel.com March 2008 2 M9999-030308-A Micrel, Inc. MIC5325 Evaluation Board PCB Layout Recommendations Top Layer Bottom Layer March 2008 3 M9999-030308-A Micrel, Inc. MIC5325 Evaluation Board MICREL, INC. 2180 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. © 2007 Micrel, Incorporated. March 2008 4 M9999-030308-A