MIC94325/45/55 Evaluation Board 500mA LDO with Ripple Blocker Technology General Description Getting Started The MIC943x5 Ripple Blocker™ is a monolithic integrated circuit that provides low-frequency ripple attenuation (switching noise rejection) to a regulated output voltage. This is important for applications, such as RF applications, where switching noise cannot be tolerated by sensitive downstream circuits. The MIC94325/45/55 maintains high power supply ripple rejection (PSRR) with input voltage operating near the output voltage level to improve overall system efficiency. 1. Connect an External Supply to VIN. Apply the desired input voltage to the VIN and ground terminal of the evaluation board, paying careful attention to polarity and supply voltage (1.8V ≤ VIN ≤ 3.6V). The MIC943x5 operates from an input voltage of 1.8V to 3.6V. The MIC943x5 options include fixed (MIC94345/55) or adjustable (MIC94325) output voltages. The MIC94355 version offers an auto-discharge to discharge the output capacitor when the part is disabled. Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. Requirements The MIC94325/45/55 evaluation board requires an input power supply that can deliver greater than 800mA at a voltage range of 1.8V to 3.6V. The output load can be either active or passive. Precautions The MIC94325/45/55 evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN terminal may damage the device. 2. Enable/Disable the MIC94325/45/55. The evaluation board is supplied with a 100kΩ pull-up resistor to VIN, which makes the on state the default. To disable the output, jumper the EN terminal to ground. 3. Connect the Load. Connect the load to the VOUT terminal and the ground terminal. The load can be either passive (resistor) or active (electronic load). Be sure to monitor the output voltage at the VOUT terminal. Ordering Information Part Number Description MIC94325YMT EV 500mA LDO Ripple Blocker Evaluation Board MIC94355-4YMT EV 500mA LDO Ripple Blocker Evaluation Board (VOUT = 1.2V) MIC94355-FYMT EV 500mA LDO Ripple Blocker Evaluation Board (VOUT = 1.5V) MIC94355-GYMT EV 500mA LDO Ripple Blocker Evaluation Board (VOUT = 1.8V) MIC94355-MYMT EV 500mA LDO Ripple Blocker Evaluation Board (VOUT = 2.8V) MIC94355-SYMT EV 500mA LDO Ripple Blocker Evaluation Board (VOUT = 3.3V) Ripple Blocker is a trademark of Micrel, 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 June 11, 2013 Revision 1.0 Micrel, Inc. MIC94325/45/55 Evaluation Board Power Supply Ripple Rejection (PSRR) Measurements PSRR measurements can be made using either dedicated PSRR test equipment or a PSRR interface board and a network analyzer. The network analyzer can sweep the AC frequency and perform a comparison measurement of the amplitude on the input and output. With this method, the network analyzer is configured for an A/R measurement. The problem comes when trying to impose the network analyzer’s AC signal with the DC input voltage to the MIC94325/45/55. The circuit shown in Figure 3 solves this problem by using the MIC911 as a summing amplifier. Figure 1 shows the frequency response of the MIC94325. MIC94325 PSRR COUT = 4.7µF CFF = 3.3nF -20 VIN = 2.7V -30 COUT = 4.7µF -40 500mA CFF = 3.3nF PSRR (dB) -50 -60 300mA -70 -80 10mA -90 -100 -110 -120 10 10 100 100 1K 10K 100K 1M 10M 1,000 10,000 100,00 1,000,0 10,000, 0 00 000 FREQUENCY (Hz) Figure 1. MIC94325 Rippled Blocker Frequency Response For high-frequency measurements (above 1MHz), pay careful attention to the test set-up configuration because it is easy to introduce noise into the grounds. That gives inaccurate measurements, as shown in Figure 2. Figure 3. Network Analyzer Set-Up The summing amplifier adds the VSUPPLY (DC voltage) and the network analyzer’s AC signal. Because the network analyzer’s source is 50Ω impedance, it may be neglected. The DC voltage seen at the non-inverting side is half of the VSUPPLY voltage. The output is gained up by 2 with the 1kΩ resistor divider to the non-inverting side. This sums the AC and DC voltages with an overall gain of 1. 1kΩ 1kΩ 1kΩ VOUT = VSUPPLY + VNETWORKANALYZER 1 + 1kΩ + 1kΩ 1kΩ 1kΩ + 1kΩ 1 1 VOUT = VSUPPLY + VNETWORKANALYZER (2) 2 2 Figure 2. High-Frequency Noise on Measurement System The inductance of test probes connected to the evaluation board at higher frequencies is a factor that can create a differential between the device under test and test measurement system grounds. Adding a low-value resistor (2Ω) in series with the input capacitor to ground and using a test measurement system that can make differential measurements will help to reduce these effects. June 11, 2013 VOUT = VSUPPLY + VNETWORKANALYZER Eq. 1 2 Revision 1.0 Micrel, Inc. MIC94325/45/55 Evaluation Board Evaluation Board Schematic (Adjustable) Bill of Materials Item C1, C2 C3 R1, R2, R4 R3 U1 Part Number CL10A475K08NNNC C1608X7R2AP/NK CRCW0402100KFKED CRCW04022R00FKED MIC943X5YMT Manufacturer Samsung (1) (2) TDK (3) Vishay (3) Vishay (4) Micrel, Inc. Description Qty. Capacitor, 4.7µF Ceramic, 16V, X5R, Size 0603 2 Capacitor, 10nF Ceramic, 50V, X7R, Size 0603 1 Resistor, 100kΩ, Size 0402 3 Resistor, 2.0Ω, Size 0402 1 500mA LDO with Ripple Blocker Technology 1 Notes: 1. Samsung: www.samsung.com. 2. TDK: www.tdk.com. 3. Vishay: www.vishay.com. 4. Micrel, Inc.: www.micrel.com. June 11, 2013 3 Revision 1.0 Micrel, Inc. MIC94325/45/55 Evaluation Board Evaluation Board Schematic (Fixed) Bill of Materials Item C1, C2 R1 R2 U1 Part Number CL10A475K08NNNC CRCW04022R0FKED CRCW0402100KFKED MIC94355-XYMT Manufacturer Samsung (5) (6) Vishay Description Capacitor, 4.7µF Ceramic, 16V, X5R, Size 0603 Qty. 2 Resistor, 2.0Ω, Size 0402 (6) Vishay (7) Micrel, Inc. Resistor, 100kΩ, Size 0402 2 500mA LDO with Ripple Blocker Technology 1 Notes: 5. Samsung: www.samsung.com. 6. Vishay: www.vishay.com. 7. Micrel, Inc.: www.micrel.com. June 11, 2013 4 Revision 1.0 Micrel, Inc. MIC94325/45/55 Evaluation Board PCB Layout Recommendations (MIC94325) Top Layer Bottom Layer June 11, 2013 5 Revision 1.0 Micrel, Inc. MIC94325/45/55 Evaluation Board PCB Layout Recommendations (MIC94345/55) Top Layer Bottom Layer June 11, 2013 6 Revision 1.0 Micrel, Inc. MIC94325/45/55 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 Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. 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. © 2013 Micrel, Incorporated. June 11, 2013 7 Revision 1.0