MIC23030 Evaluation Board 8MHz PWM 400mA Buck Regulator with HyperLight Load™ General Description The MIC23030 is a 400mA 8MHz switching regulator featuring HyperLight Load™ mode. The MIC23030 is highly efficient throughout the entire output current range, drawing just 21µA of quiescent current in operation. The tiny 1.6 x 1.6mm MLF® package, in combination with the 8MHz switching frequency, enables a compact sub-1mm height solution with only three external components. The MIC23030 provides accurate output voltage regulation under the most demanding conditions and responds extremely quickly to a load transient with exceptionally small output voltage ripple. Factoring in the output current, the internal circuitry of the MIC23030 automatically selects between two modes of operation for optimum efficiency. Under light load conditions, the MIC23030 goes into HyperLight Load™ mode. HyperLight Load™ uses a Pulse-Frequency Modulation (PFM) control scheme that controls the off time at light load. This proprietary architecture reduces the amount of switching needed at light loads, thereby increasing operating efficiency. The MIC23030 attains up to 83% efficiency at 1mA output load. As the load current increases beyond approximately 100mA, the device operates using the Pulse-Width Modulation (PWM) method for up to 91% efficiency at higher loads. The two modes of operation ensure the highest efficiency across the entire load range. The MIC23030 operates from an input voltage range of 2.7V to 5.5V and features internal power MOSFETs that deliver up to 400mA of output current. This step-down regulator provides an output voltage accuracy of +/-2.5% across the junction temperature range of -40ºC to +125ºC. The MIC23030 is available in fixed or adjustable versions supporting an output voltage as low as 0.7V. Requirements The MIC23030 evaluation board requires an input power source that is able to deliver greater than 500mA at 2.7V to the MIC23030. The output load can either be an active (electronic) or passive (resistive) load. Getting Started 1. Connect an external supply to the VIN (J1) terminal. Apply the desired input voltage to VIN (J1) and ground (J2) terminals of the evaluation board, paying careful attention to polarity and supply 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, since the ammeter and/or power lead resistance can reduce the voltage supplied to the device. 2. Connect a load to the VOUT (J3) and ground terminal (J4). The load can be either passive (resistive) or active (electronic load). An ammeter may be placed between the load and the output terminal. Ensure the output voltage is monitored at the VOUT (J3) terminal. 3. Enable the MIC23030. The MIC23030 evaluation board has a pull-up resistor to VIN. To disable the device, apply a voltage below 0.5V to the EN (J5) terminal or place a jumper on JP1 to ground the enable. In the absence of the pull-up resistor, the device is enabled by applying a voltage greater than 1.2V to the EN (J5) terminal. The enable pin must be either pulled high or low for proper operation. Removing the pull-up resistor and leaving the pin floating will cause the regulator to operate in an indeterminable state. Output Voltage The MIC23030 evaluation board is available with the following output voltage options listed below: Ordering Information Part Number Description MIC23030-AYMT EV Adjustable Output Evaluation Board MIC23030-CYMT EV 1.0V Fixed Output Evaluation Board MIC23030-4YMT EV 1.2V Fixed Output Evaluation Board MIC23030-FYMT EV 1.5V Fixed Output Evaluation Board MIC23030-GYMT EV 1.8V Fixed Output Evaluation Board Note: Other voltage options available on request HyperLight Load is a trademark of Micrel, Inc. MLF is a registered trademark of Amkor Technology. 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 2008 M9999-072208-A Micrel, Inc. MIC23030 Evaluation Board continuous conduction mode (CCM) and switches at a frequency centered at 8MHz. The equation to calculate the load where the MIC23030 goes into continuous conduction mode is approximated by the following formula: Output Voltage (Adjustable Option Only) The output voltage of the MIC23030-AYMT regulator is determined by feedback resistors R1 and R2 whose values are calculated as follows: ⎛ (V − VOUT ) × D ⎞ ⎟⎟ I LOAD > ⎜⎜ IN 2L × f ⎝ ⎠ ⎛ R1 ⎞ VOUT = 0.62V × ⎜ + 1⎟ ⎝ R2 ⎠ As shown in the previous equation, the load at which MIC23030 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). This is illustrated in the graph below. Suitable inductors for the MIC23030 range from 0.47µH to 2.2µH. The device may be tailored to enter HyperLight Load™ mode or PWM mode at a specific load current by selecting the appropriate inductor. For example, if a 2.2µH inductor is selected in a 3.6VIN to 1.8VOUT application, the MIC23030 will transition into PWM mode at a load of approximately 30mA. If under the same condition a 0.47µH inductor is chosen, the MIC23030 will transition into PWM mode at approximately 120mA. The output on the evaluation board is by default set to 1.8V (R1=383kΩ, R2=200kΩ), but can easily be modified by removing R1 and replacing it with the value that yields the desired output voltage. ⎛V ⎞ R1 = ⎜⎜ OUT − 1⎟⎟ × R2 0.62V ⎝ ⎠ For optimum transient response performance, R2 should be in the range of 180kΩ to 220kΩ. HyperLight Load™ Mode MIC23030 uses a patented minimum on and off time control loop at light loads. When the output voltage falls below the lower 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. Once the output voltage rises to the higher regulation threshold, the error comparator turns the PMOS off for a minimum off time until the output drops down to the lower threshold. The NMOS acts as an ideal rectifier that conducts when the PMOS is off. Using a NMOS switch instead of a diode, reduces power dissipation as the current is sourced from ground. In discontinuous mode, the MIC23030 works in pulse frequency modulation (PFM) to regulate the output. As the output current increases, the off-time decreases, more energy is delivered to the output. This switching scheme improves the efficiency of MIC23030 during light load currents by activating the power FETs only as needed. As the load current increases, the MIC23030 goes into August 2008 SW Frequency vs. Inductance 2 M9999-072208-A Micrel, Inc. MIC23030 Evaluation Board MIC23030 Typical Application Circuit (Fixed) Bill of Materials Item C1, C2 R1 L1 Part Number C1608X5R0J475K CRCW06031003FT1 (1) TDK Description 4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2 100kΩ, 1%, Size 0603 1 (3) Vishay Murata 0.47µH, 0.9A, 90mΩ, L2mm x W1.25mm x H0.5mm LQH32CNR47M33 Murata(3) 0.47µH, 1.1A, 42mΩ, L3.2mm x W2.5mm x H2.0mm LQM31PNR47M00 (3) Murata 0.47µH, 1.4A, 80mΩ, L3.2mm x W1.6mm x H0.85mm (1) GLF251812T1R0M TDK MIPF2520D1R5 FDK(4) MIC23030-xYMT Qty. (2) LQM21PNR47M00 EPL2010-471 U1 Manufacturer Coilcraft 1 1µH, 0.8A, 100mΩ, L2.5mm x W1.8mm x H1.35mm 1.5µH, 1.5A, 70mΩ, L2.5mm x W2mm x H1.0mm (5) Micrel, Inc. (6) 0.47µH, 1.6A, 40mΩ, L2.0mm x W1.8mm x H1.0mm 8MHz 400mA Buck Regulator with HyperLight Load™ Mode 1 Notes: 1. TDK: www.tdk.com 2. Vishay: www.vishay.com 3. Murata: www.murata.com 4. FDK: www.fdk.co.jp 5. Coilcraft: www.coilcraft.com 6. Micrel, Inc.: www.micrel.com August 2008 3 M9999-072208-A Micrel, Inc. MIC23030 Evaluation Board MIC23030 Typical Application Circuit (Adjustable 1.8V) Bill of Materials Item C1, C2 Part Number C1608X5R0J475K Manufacturer (1) TDK Description Qty. 4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2 C3 OPEN (2) R1 CRCW06033833FT1 Vishay 383kΩ, 1%, Size 0603 1 R2 CRCW06032003FT1 Vishay(2) 200kΩ, 1%, Size 0603 1 CRCW06031003FT1 (2) 100kΩ, 1%, Size 0603 1 (3) R3 L1 LQM21PNR47M00 Murata 0.47µH, 0.9A, 90mΩ, L2mm x W1.25mm x H0.5mm LQH32CNR47M33 Murata(3) 0.47µH, 1.1A, 42mΩ, L3.2mm x W2.5mm x H2.0mm LQM31PNR47M00 (3) Murata TDK MIPF2520D1R5 FDK(4) MIC23030-AYMT 0.47µH, 1.4A, 80mΩ, L3.2mm x W1.6mm x H0.85mm (1) GLF251812T1R0M EPL2010-471 U1 Vishay 1.5µH, 1.5A, 70mΩ, L2.5mm x W2mm x H1.0mm Coilcraft(5) Micrel, Inc. 1 1µH, 0.8A, 100mΩ, L2.5mm x W1.8mm x H1.35mm (6) 0.47µH, 1.6A, 40mΩ, L2.0mm x W1.8mm x H1.0mm 8MHz 400mA Buck Regulator with HyperLight Load™ Mode 1 Notes: 1. TDK: www.tdk.com 2. Vishay: www.vishay.com 3. Murata: www.murata.com 4. FDK: www.fdk.co.jp 5. Coilcraft: www.coilcraft.com 6. Micrel, Inc.: www.micrel.com August 2008 4 M9999-072208-A Micrel, Inc. MIC23030 Evaluation Board PCB Layout Recommendations Fixed Top Layer Fixed Bottom Layer Adjustable Top Layer August 2008 Adjustable Bottom Layer 5 M9999-072208-A Micrel, Inc. MIC23030 Evaluation Board Package Information SIDE VIEW 6-pin 1.6mm x 1.6mm Thin MLF® (MT) 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 aplpiances, 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. © 2008 Micrel, Incorporated. August 2008 6 M9999-072208-A