MIC23156 Evaluation Board 1.5A, 3MHz Synchronous Buck Regulator with HyperLight Load® and I2C Control for Dynamic Voltage Scaling General Description Getting Started The MIC23156 evaluation board allows the customer to evaluate a fully-integrated 1.5A, 3MHz synchronous buck ® regulator that features HyperLight Load mode, a power good (PGOOD) output indicator, a programmable soft2 start, and an output voltage scaling control through I C. The MIC23156 is highly efficient throughout the output current range, drawing just 30µA of quiescent current during operation. The ability to dynamically change the 2 output voltage in 10mV steps through I C and maintain high output voltage accuracy makes the MIC23156 simple to use and versatile. The MIC23156 is available in both 16ball, 0.4mm pitch, 1.81mm × 1.71mm wafer level chip ® scale (WLCSP), and 17-pin 2.8mm × 2.5mm MLF packages. 1. Connect an external supply to the VIN (J1) and GND (J2) terminals. With the output of the power supply disabled, set its voltage to the desired input test voltage (2.7V ≤ VIN ≤ 5.5V). An ammeter may be placed between the input supply and the VIN (J1) terminal. Be sure to monitor the supply voltage at the VIN (J1) terminal, as the ammeter and/or power lead resistance can reduce the voltage supplied to the device. Requirements The MIC23156 evaluation board requires a single 10W power source adjustable from 2.7V to 5.5V. The loads can either be active (electronic load) or passive (resistor), and must be able to dissipate 5W. It is ideal, but not essential, to have an oscilloscope available to view the circuit waveforms. The simplest tests require two voltage meters to measure input and output voltages. Efficiency measurements require two voltage meters and two ammeters to prevent errors caused by measurement inaccuracies. 3. Connect a load to the VOUT (J6 in YML and J3 in YCS) and GND (J7 in YML and J4 in YCS) terminals. The load can be either passive (resistive) or active (electronic load). An ammeter may be placed between the load and the output terminal. Make sure the output voltage is monitored at the VOUT terminal. The board is also equipped with a 2-pin connector (JP2) to allow for output voltage monitoring. 2 To use the dynamic voltage scaling feature, an I C serial 2 programmer board (MICUSB I C Dongle EV), software package/kit (available for download online), and a computer are necessary. Precautions There is no reverse input protection on this board. Be careful when connecting the input source to ensure correct polarity is observed. Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. 2. Jumper VSEL via TP1. 2 Pulling VSEL high to VCC in MLF or VI C in YCS sets the default output voltage to 0.8V. Setting VSEL low to GND sets the default output voltage to 1.0V. 4. Enable the MIC23156 via TP2. To enable the MIC23156, jumper TP2 to VCC in YML or VIN in YCS. To disable the device, jumper TP2 to GND. An alternative method of enabling and disabling the EN pin is by applying a second power source to the EN and GND terminals. Do not leave this pin floating. Ordering Information Part Number Description MIC23156-0YML EV( 1.5A synchronous buck regulator with I2C in a 17-pin 2.8mm × 2.5mm MLF. MIC23156-0YCS EV 1.5A synchronous buck regulator with I2C in a 16-ball 1.81mm × 1.71mm WLCSP. MICUSB Dongle I2C serial programmer board. 1) Note: 1. Contact Micrel Marketing for availability. HyperLight Load is a registered 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 August 27, 2013 Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board 2 5. Power Good (J3 in YML). A power good (PGOOD) test point is provided to monitor the PGOOD function (available only on the YML evaluation board). Connect a voltage meter or an oscilloscope to the PGOOD pin. 7. Open and control the MIC23156 via the I C serial programmer interface Download the software package/kit found on the MIC23156 product page on Micrel’s website Open the 2 I C interface and follow the steps below: 2 2 a. Open the I C serial programmer interface and click Test. The status bar at the bottom of the window should change from value to Target OK. 6. Connect the I C serial programmer board (MICUSB 2 I C Dongle evaluation board) to JP1 of the MIC23156 evaluation board. 2 Make sure the switch on the I C serial programmer board is switched to “I2C” and not “NOM”. b. Click the Registers tab and then click Read. The PGOOD status box will automatically be checked if the output voltage regulation is above the PGOOD fault threshold. If the UVLO box is checked, it means the input voltage is too low. If the TSD box is checked, it means the internal die temperature is too high and the device is now in thermal shutdown to prevent damage. 2 Plug the 9-pin connector of the I C board to JP1 of the MIC23156 evaluation board. Take extra care when connecting the two boards together and make sure the 2 GND pins are matched (GND of I C board connects to 2 GND of MIC23156). Then connect the I C serial programmer board to a laptop or desktop using a USB to Mini-B USB type cable. c. August 27, 2013 2 Click Offline Mode once and it will toggle to Direct Editing Mode. In direct editing mode, any 2 modifications made in the I C interface, such as enabling/disabling the device, setting a long soft start, or changing the output voltage, will be recognized instantaneously at the VOUT terminal of the MIC23156 evaluation board. Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board Note: As soon as the input supply or enable pin on the MIC23156 evaluation board is powered down and up, the output voltage automatically returns to its default values. In the case of MIC23156-0YML and MIC23156-0YCS, the default output voltages are 0.8V (VSEL is high) and 1.0V (VSEL is low). August 27, 2013 3 Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board Evaluation Board The MIC23156 has the ability to switch from a high output to a low output voltage and vice versa in a matter of hundreds of microseconds. The default output voltage 2 setting for VSEL ≤ (0.3 × VI C) is 1.0V, and 0.8V for VSEL 2 ≥ (0.7 × VI C). The programmable output voltage ranges 2 from 0.7V to 2.4V and can be easily changed via I C programming. HyperLight Load Mode MIC23156 uses a minimum on and off time proprietary control loop (patented by Micrel). When the output voltage falls below the regulation threshold, the error comparator begins a switching cycle that turns the PMOS on and keeps it on for the duration of the minimum-on-time. This increases the output voltage. If the output voltage is over the regulation threshold, then the error comparator turns the PMOS off for a minimum-off-time until the output drops below the threshold. The NMOS acts as an ideal rectifier that conducts when the PMOS is off. Using an NMOS switch instead of a diode allows for lower voltage drop across the switching device when the NMOS is on. The synchronous switching combination between the PMOS and the NMOS allows the control loop to work in discontinuous mode for light load operations. In discontinuous mode, the MIC23156 works in pulse frequency modulation (PFM) to regulate the output. As the output current increases, the off-time decreases, thus providing more energy to the output. This switching scheme improves the efficiency of MIC23156 during light load currents by only switching when it is needed. Features Soft-Start Capacitor (C4) The MIC23156 has a nominal 820kΩ resistor charging the capacitor on the SS pin. This enables the output to follow a controlled soft-start characteristic. Setting C4 to 120pF sets the startup time to approximately 230µs. The start-up time can be determined by Equation 1: TSS = 820 × 10 3 × ln(10) × C SS As the load current increases, the MIC23156 goes into continuous conduction mode (CCM) and switches at a frequency centered at 3MHz. The equation to calculate the load when the MIC23156 goes into continuous conduction mode is approximated by Equation 2: Eq. 1 The action of the soft-start capacitor is to control the rise time of the internal reference voltage between 0% and 100% of its nominal steady state value. (V − VOUT ) × D ILOAD > IN 2L × f Power Good (PGOOD) The YML evaluation board has a test point provided for monitoring the power good (PGOOD) feature. This is an open-drain connection with an on-board pull-up resistor of 100kΩ to the output voltage. PGOOD is asserted high approximately 70µs after the output voltage passes 90% of the nominal set voltage. As shown in Equation 2, the load at which MIC23156 transitions from HyperLight Load mode to PWM mode is a function of the input voltage (VIN), output voltage (VOUT), duty cycle (D), inductance (L) and frequency (f). The “Switching Frequency vs. Output Current” graph in the Evaluation Board Performance section shows an example of how, when the output current increases, the switching frequency also increases, until the MIC23156 goes from HyperLight Load mode to PWM mode at approximately 180mA. The MIC23156 switches at a relatively constant frequency around 3MHz after the output current is over 180mA. The PGOOD signal will remain high as long as VOUT regulates within 14% of its nominal output voltage. When VOUT regulation drops below the threshold, the PGOOD signal will trip a fault condition and assert low. VSEL Selectable output voltage is a good feature to have in a power saving system design. August 27, 2013 Eq. 2 4 Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board Evaluation Board Performance Efficiency (VOUT = 1.8V) vs. Output Current Efficiency (VOUT = 2.4V) vs. Output Current Efficiency (VOUT = 1.0V) vs. Output Current 100 100 90 90 90 80 80 VIN = 4.2V VIN = 5V 60 50 40 30 80 VIN = 5V 70 COUT = 2.2µF L = 1µH 10 VIN = 2.7V 50 40 30 100 1000 10000 100 1000 10000 35 30 25 -40°C 20 NO SWITCHING VOUT > VOUTNOM × 1.2 COUT = 2.2µF 4.0 4.5 5.0 2.6 1.1 ENABLE RISING 1 0.9 ENABLE FALLING 0.8 0.7 3.5 4 4.5 INPUT VOLTAGE (V) Δ Output Voltage vs. DAC DNL VOUT Rise Time vs. CSS 5 5.5 0 10000 1000 VOUT = 1.0V COUT = 2.2µF 10 50 75 100 125 August 27, 2013 150 175 SWITCHING FREQUENCY (MHz) RISE TIME (µs) 100000 100 9 75 100 125 150 175 4.0 9.5 IOUT = 250mA COUT = 2.2µF 50 Switching Frequency vs. Output Current 10.5 10 25 DAC VOLTAGE CODE 1000000 DAC VOLTAGE CODE 1.4 0.6 3 10000000 25 1.8 IOUT = 250mA COUT = 2.2µF INPUT VOLTAGE (V) 11 0 2.2 1 2.5 5.5 10000 Output Voltage vs. DAC Linearity 0.5 3.5 1000 0.6 10 3.0 100 OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) ENABLE THRESHOLD (V) 125°C 2.5 COUT = 2.2µF L = 1µH 10 1.2 25°C VIN = 2.7V 30 Enable Threshold vs. Input Voltage 45 VIN = 3.6V 40 OUTPUT CURRENT (mA) Quiescent Current vs. Input Voltage 15 VIN = 5V 50 0 10 OUTPUT CURRENT (mA) 40 60 10 0 10 70 20 COUT = 2.2µF L = 1µH 10 0 QUIESCENT CURRENT (µA) VIN = 3.6V 60 20 20 Δ OUTPUT VOLTAGE (mV) VIN = 4.2V EFFICIENCY (%) VIN = 3.6V 70 EFFICIENCY (%) EFFICIENCY (%) 100 3.5 3.0 2.5 1.0µH 2.0 2.2µH 1.5 1.0 VOUT = 1.8V COUT = 2.2µF 0.5 0.0 100 1000 10000 CSS (pF) 5 100000 1000000 10 100 1000 10000 OUTPUT CURRENT (mA) Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board Evaluation Board Schematic – MIC23156-0YML August 27, 2013 6 Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board Evaluation Board Schematic – MIC23156-0YCS August 27, 2013 7 Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board Bill of Materials Item Part Name 06036D225KAT2A C1, C5 GRM188R60J225KE19D C1608X5R0J225KT 06036D106MAT2A C2 GRM188R60J106ME47D C1608X5R0J106M C3 ECA-1AHG221 06035A121JAT2A C4 GRM1885C1H121JA01D C1608C0G1H121JT L1 CDRH4D28CLDNP-1R0P LQH44PN1R0NJ0 Manufacturer Description Qty. (2) AVX Murata (3) 2.2µF, 6.3V, X5R, 0603 2 10µF, 6.3V, X5R, 0603 1 Aluminum capacitor, 220µF, 10V, 20%, radial 1 120pF, 50V, 0603 1 (4) TDK AVX Murata TDK Panasonic (5) AVX Murata TDK Sumida (6) 1µH, 3.0A, 14mΩ, L5.1mm × W5.1mm × H3.0mm 1 1µH, 2.0A, 48mΩ, L4.0mm × W4.0mm × H1.1mm Murata 4.7kΩ, 1%, 1/10W, 0603 2 Vishay/Dale 100kΩ, 1%, 1/10W, 0603 1 CRCW06030000Z0EA Vishay/Dale 0Ω, 1/10W, 0603 1 R5 CRCW060310R0FKEA Vishay/Dale 10Ω, 1%, 1/10W, 0603 1 U1 MIC23156-0YML 1.5A, 3MHz Synchronous Buck Regulator with 2 HyperLight Load and I C Control for Dynamic Voltage Scaling 1 R1, R2 CRCW06034K70FKEA R3 CRCW06031003FKEA R4 Vishay/Dale (7) (8) Micrel, Inc. Notes: 2. AVX: www.avx.com. 3. Murata: www.murata.com. 4. TDK: www.tdk.com. 5. Panasonic: www.industrial.panasonic.com. 6. Sumida: www.sumida.com. 7. Vishay: www.vishay.com. 8. Micrel, Inc.: www.micrel.com. August 27, 2013 8 Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board PCB Layout Recommendations (MLF Package) Top Layer Bottom Layer August 27, 2013 9 Revision 1.1 Micrel, Inc. MIC23156 Evaluation Board PCB Layout Recommendations (YCS Package) Top Layer Bottom Layer August 27, 2013 10 Revision 1.1 Micrel, Inc. MIC23156 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. August 27, 2013 11 Revision 1.1