MIC94310-GYCS-EV Microchip

MIC94310 Evaluation Board 200mA LDO with Ripple Blocker Technology General Description Getting Started The MIC94310 is a 200mA Low Dropout (LDO) Connect an External Supply to V . Apply the IN regulator that provides high power supply ripple desired input voltage to the V and ground terminal IN rejection (PSRR). This is important for applications of the evaluation board, paying careful attention to where switching noise cannot be tolerated by sensitive polarity and supply voltage (1.8V V 3.6V). IN downstream circuits such as in RF applications. The Enable/Disable the MIC94310. The evaluation MIC94310 maintains high power supply ripple rejection board is supplied with 100k pull-up resistor to V IN (PSRR) with input voltage operating near the output for default on state. To disable the output, simply voltage level to improve overall system efficiency. jumper the EN terminal to ground. The MIC94310 operates from an input voltage of 1.8V to Connect the Load. Connect the load to the V OUT 3.6V. terminal and the ground terminal. The load can be Datasheets and support documentation can be found on either a passive (resistor) or active (electronic load). Micrels web site at www.micrel.com. Be sure to monitor the output voltage at the V OUT terminal. Requirements The MIC94310 evaluation board requires an input power supply that is capable of delivering greater than 400mA Ordering Information at a voltage range of 1.8V to 3.6V. The output load can Part Number Description be either active or passive. 200mA LDO Ripple Blocker CSP Precautions MIC94310-GYCS EV Package Evaluation Board V =1.8V The MIC94310 evaluation board does not have reverse OUT polarity protection. Applying a negative voltage to the 200mA LDO Ripple Blocker Thin V terminal may damage the device. MIC94310-GYMT EV MLF Package Evaluation Board IN V =1.8V OUT Ripple Blocker 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 Micrel, Inc. MIC94310 Evaluation Board PSRR measurements may be made using either Power Supply Ripple Rejection (PSRR) dedicated PSRR test equipment or with a PSRR interface board and a network analyzer. The network Measurements analyzer can sweep the AC frequency and perform a Figure 1 illustrates the frequency response of the comparison measurement of the amplitude on the MIC94310. input and output. With this method, the network analyzer is configured for an A/R measurement. The difficulty arises when trying to impose the network PSRR C = 1F OUT analyzers AC signal with the DC input voltage to the MIC94310. The circuit shown in Figure 3 0 accomplishes this by using the MIC911 as a summing -20 amplifier. The summing amplifier adds the V SUPPLY (DC voltage) and the network analyzers AC signal. As -40 I = 200mA OUT the network analyzers source is 50 impedance it I = 100mA OUT may be neglected, the DC voltage seen at the non- -60 inverting side is half of the V voltage. The output SUPPLY is gained up by 2 with the 1k resistor divider to the -80 non-inverting side. This sums the AC and DC voltages -100 with an overall gain of 1. V = 2.5V + 40mVpp IN V = 1.8V OUT I = 10mA OUT -120 10 100 1K 10K 100K 1M 10M 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 FREQUENCY (Hz) Figure 1. MIC94310 Ripple Blocker Frequency Response For high-frequency measurements (above 1MHz), careful attention must be made to the test set-up configuration as it is easy to introduce noise into the grounds which will give inaccurate measurements as shown in Figure 2. Figure 2. High-Frequency Noise on Measurement System The inductance of test probes connected to the Figure 3. Network Analyzer Set-Up evaluation board at higher frequencies becomes a factor which can create a differential between the device under test and test measurement system grounds. Adding a low-value resistor (2 ) in series with the input capacitor to ground and utilizing a test measurement system capable of making differential measurements will help to reduce these effects. 2 M9999-020912 February 2012 (408) 944-0800 PSRR (dB)