MIC2164/-2/-3/C Synchronous Buck Controllers Featuring Adaptive On-Time Control 28V Input, Constant Frequency Hyper Speed Control™ Family General Description Features The Micrel MIC2164/-2/-3/C are constant-frequency, synchronous buck controllers featuring adaptive on-time control. The MIC2164/-2/-3/C are the first products in the new Hyper Speed Control™ family of buck controllers introduced by Micrel. The MIC2164/-2/-3/C controllers operate over an input supply range of 3V to 28V, and are independent of the IC supply voltage. The devices are capable of supplying 25A output current. While the MIC2164 operates at 300kHz, the MIC2164-2 operates at 600kHz, and the MIC2164-3 operates at 1MHz. A unique Hyper Speed Control™ architecture allows for ultrafast transient response while reducing the output capacitance and also makes High VIN/Low VOUT operation possible. The MIC2164/-2/-3/C controllers utilizes an architecture which is adaptive TON ripple controlled. A UVLO feature is provided to ensure proper operation under power-sag conditions to prevent the external power MOSFET from overheating. A soft start feature is provided to reduce the inrush current. Foldback current limit and “hiccup” mode short-circuit protection ensure FET and load protection. The MIC2164/-2/-3/C controllers are available in a 10-pin MSOP (MAX1954A-compatible) package with a junction operating range from –40°C to +125°C. All support documentation can be found on Micrel’s web site at: www.micrel.com. • • • • • • • • • • • • • • Hyper Speed Control™ architecture enables - High delta V operation (VHSD = 28V and VOUT = 0.8V) - Smaller output capacitors than competitors 3V to 28V input voltage Any CapacitorTM stable - Zero ESR to high ESR 25A output current capability 300kHz/600kHz/1MHz switching frequency Adaptive on-time mode control Adjustable output from 0.8V to 5.5V with ±1% (MIC2164/-2/-3) or ±3% (MIC2164C) FB accuracy Up to 95% efficiency Foldback current-limit and “hiccup” mode short-circuit protection 6ms Internal soft start Thermal shutdown Safe start-up into pre-biased loads –40°C to +125°C junction temperature range Available in 10-pin MSOP package Applications • • • Set-top box, gateways and routers Printers, scanners, graphic cards and video cards Telecommunication, PCs and servers ________________________________________________________________________________________________________________________ Typical Application MIC2164 12V to 3.3V Efficiency 100 95 EFFICIENCY (%) 90 85 80 75 70 65 60 VIN=5V 55 50 MIC2164/-2/-3/C Synchronous Controllers Featuring Adaptive On-Time Control 0 4 8 12 16 20 OUTPUT CURRENT (A) Hyper Speed Control and Any Capacitor 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 September 2010 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Ordering Information Part Number Voltage Switching Frequency Accuracy Junction Temperature Range Package Lead Finish MIC2164YMM Adjustable 300kHz ±1% –40° to +125°C 10-pin MSOP Pb-Free MIC2164-2YMM Adjustable 600kHz ±1% –40° to +125°C 10-pin MSOP Pb-Free MIC2164-3YMM Adjustable 1MHz ±1% –40° to +125°C 10-pin MSOP Pb-Free MIC2164CYMM Adjustable 270kHz ±3% –40° to +125°C 10-pin MSOP Pb-Free Pin Configuration 10-Pin MSOP (MM) Pin Description Pin Number Pin Name 1 HSD High-Side N-MOSFET Drain Connection (input): Power to the drain of the external high-side N-channel MOSFET. The HSD operating voltage range is from 3V to 28V. Input capacitors between HSD and the power ground (PGND) are required. 2 EN Enable (input): A logic level control of the output. The EN pin is CMOS-compatible. Logic high or floating = enable, logic low = shutdown. In the off state, supply current of the device is greatly reduced (typically 0.8mA). 3 FB Feedback (input): Input to the transconductance amplifier of the control loop. The FB pin is regulated to 0.8V. A resistor divider connecting the feedback to the output is used to adjust the desired output voltage. 4 GND 5 IN Input Voltage (input): Power to the internal reference and control sections of the MIC2164/-2/-3. The IN operating voltage range is from 3V to 5.5V. A 1µF and 0.1µF ceramic capacitors from IN to GND are recommended for clean operation. 6 DL Low-Side Drive (output): High-current driver output for external low-side MOSFET. The DL driving voltage swings from ground-to-IN. 7 PGND 8 September 2010 DH Pin Function Signal ground. GND is the ground path for the device input voltage VIN and the control circuitry. The loop for the signal ground should be separate from the power ground (PGND) loop. Power Ground. PGND is the ground path for the MIC2164/-2/-3 buck converter power stage. The PGND pin connects to the sources of low-side N-Channel MOSFETs, the negative terminals of input capacitors, and the negative terminals of output capacitors. The loop for the power ground should be as small as possible and separate from the Signal ground (GND) loop. High-Side Drive (output): High-current driver output for external high-side MOSFET. The DH driving voltage is floating on the switch node voltage (LX). It swings from ground to VIN minus the diode drop. Adding a small resistor between DH pin and the gate of the high-side N-channel MOSFETs can slow down the turn-on and turn-off time of the MOSFETs. 2 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Pin Description (Continued) Pin Number Pin Name 9 10 September 2010 LX BST Pin Function Switch Node and Current Sense input: High current output driver return. The LX pin connects directly to the switch node. Due to the high speed switching on this pin, the LX pin should be routed away from sensitive nodes. LX pin also senses the current by monitoring the voltage across the low-side MOSFET during OFF time. In order to sense the current accurately, connect the low-side MOSFET drain to LX using a Kelvin connection. Boost (output): Bootstrapped voltage to the high-side N-channel MOSFET driver. A Schottky diode is connected between the IN pin and the BST pin. A boost capacitor of 0.1μF is connected between the BST pin and the LX pin. Adding a small resistor in series with the boost capacitor can slow down the turn-on time of high-side N-Channel MOSFETs. 3 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Absolute Maximum Ratings(1) Operating Ratings(2) IN, FB, EN to GND .......................................... −0.3V to +6V BST to LX ....................................................... −-0.3V to +6V BST to GND .................................................. −0.3V to +37V DH to LX............................................−0.3V to (VBST + 0.3V) DL, COMP to GND.............................. −0.3V to (VIN + 0.3V) HSD to GND.................................................... −0.3V to 31V PGND to GND .............................................. −0.3V to +0.3V Junction Temperature .............................................. +150°C Storage Temperature (TS).........................−65°C to +150°C Lead Temperature (soldering, 10sec)........................ 260°C Input Voltage (VIN)............................................ 3.0V to 5.5V Supply Voltage (VHSD) ....................................... 3.0V to 28V Operating Temperature Range ................. −40°C to +125°C Junction Temperature (TJ) ........................ −40°C to +125°C Junction Thermal Resistance MSOP (θJA) ..................................................130.5°C/W Continuous Power Dissipation (TA = 70°C)..............421mW (derate 5.6mW/°C above 70°C) Electrical Characteristics(4) VBST − VLX = 5V; TA = +25°C, unless noted. Bold values indicate −40°C ≤ TJ ≤ +125°C. Parameter Condition Min. Typ. Max. Units General Operating Input Voltage (VIN) (5) 3.0 5.5 V HSD Voltage Range (VHSD) 3.0 28 V Quiescent Supply Current (VFB = 1.5V, output switching but excluding external MOSFET gate current) 1.4 3.0 mA Standby Supply Current (6) VIN = VBST = 5.5V, VHSD = 28, LX = unconnected, EN = GND 0.8 2 mA 2.7 3 V Under-Voltage Lockout Trip Level 2.4 UVLO Hysteresis 50 mV DC-DC Controller Output-Voltage Adjust Range (VOUT) 0.8 5.5 0°C ≤ TJ ≤ 85°C -1 1 −40°C ≤ TJ ≤ 125°C -2 2 TJ = 25°C (MIC2164C) -3 V Error Amplifier FB Regulation Voltage FB Input Leakage Current Current-Limit Threshold % 3 5 500 VFB = 0.8V 103 130 162 VFB = 0V 19 48 77 VFB = 0.8V (MIC2164C) 95 130 170 VFB = 0V (MIC2164C) 15 48 80 nA mV Soft-Start Soft-Start Period 6 ms Oscillator Switching Frequency (8) September 2010 MIC2164C 0.202 0.27 0.338 MIC2164 0.225 0.3 0.375 MIC2164-2 0.45 0.6 0.75 MIC2164-3 0.75 1 1.25 4 MHz M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Electrical Characteristics(4) (Continued) VBST − VLX = 5V; TA = +25°C, unless noted. Bold values indicate −40°C ≤ TJ ≤ +125°C. Parameter Maximum Duty Cycle Condition (9) Minimum Duty Cycle Min. Typ. MIC2164/ MIC2164C 87 MIC2164-2 74 MIC2164-3 66 Measured at DH, VFB = 1V 0 Max. Units % % FET Drives DH, DL Output Low Voltage ISINK = 10mA DH, DL Output High Voltage ISOURCE = 10mA 0.1 VIN − 0.1V or VBST − 0.1V V V DH On-Resistance, High State 2.1 3.3 Ω DH On-Resistance, Low State 1.8 3.3 Ω DL On-Resistance, High State 1.8 3.3 Ω DL On-Resistance, Low State 1.2 2.3 Ω LX Leakage Current VLX = 28V, VIN = 5.5V,VBST = 33.5V 50 µA HSD Leakage Current VLX = 28V, VIN = 5.5V,VBST = 33.5V 20 µA Thermal Protection Over-Temperature Shutdown 155 °C Over-Temperature Shutdown Hysteresis 10 °C 0.8 V Shutdown Control EN Logic Level Low 3V < VIN <5.5V EN Logic Level High 3V < VIN <5.5V 0.4 0.9 EN Pull-Up Current 1.2 50 V µA Note: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. 4. Specification for packaged product only. 5. The application is fully functional at low IN (supply of the control section) if the external MOSFETs have enough low voltage VTH. 6. The current will come only from the internal 100kΩ pull-up resistor sitting on the EN Input and tied to IN. 8. Measured in test mode. 9. Measured at DH. The maximum duty cycle is limited by the fixed mandatory off time TOFF of typical 363ns. September 2010 5 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Typical Characteristics MIC2164 12V to 1.5V Efficiency 100 95 90 90 90 80 75 70 65 60 85 80 75 70 65 60 VIN=5V 55 EFFICIENCY (%) 95 85 75 70 65 60 VIN=5V 4 8 12 16 50 0 20 4 8 12 16 0 20 MIC2164-3 12V to 1.5V Efficiency 100 90 80 75 70 65 EFFICIENCY (%) 90 EFFICIENCY (%) 95 90 85 85 80 75 70 65 60 VIN=5V 55 50 6 9 12 15 75 70 65 60 2 4 6 8 10 0 Feedback Voltage vs. Input Voltage 0.84 0.81 0.80 0.79 0.78 VHSD=12V VIN=5V FEEDBACK VOLTAGE (V) 0.85 0.84 FEEDBACK VOLTAGE (V) 0.85 0.82 0.83 0.82 0.81 0.80 0.79 0.78 0.77 VHSD=12V 0.76 4 8 12 16 3.5 Feedback Voltage vs. Temperature 0.82 0.81 0.80 0.79 0.78 4 4.5 5 5.5 3 680 0.796 0.794 VIN=5V 0.792 0.790 -40 -20 0 20 40 60 80 TEMPERATURE (°C) 100 120 330 320 310 300 290 280 VHSD=12V VIN=5V 270 260 250 23 28 660 640 620 600 580 560 540 VHSD=12V VIN=5V 520 500 0 4 8 12 OUTPUT CURRENT (A) September 2010 SWITCHING FREQUENCY (kHz) 700 0.798 18 MIC2164-2 Switching Frequency vs. Load 340 0.800 13 MIC2164 Switching Frequency vs. Load 350 0.802 8 HSD VOLTAGE (V) 0.808 0.804 VIN=5V 0.77 0.810 SWITCHING FREQUENCY (kHz) FEEDBACK VOLTAGE (V) 0.83 INPUT VOLTAGE (V) OUTPUT CURRENT (A) 0.806 10 0.75 3 20 8 0.76 0.75 0.75 6 Feedback Voltage vs. HSD Voltage 0.84 0 4 OUTPUT CURRENT (A) 0.85 0.76 2 OUTPUT CURRENT (A) Feedback Voltage vs. Load 0.77 VIN=5V 55 50 0 OUTPUT CURRENT (A) 0.83 15 80 50 3 12 85 VIN=5V 55 9 MIC2164-3 12V to 3.3V Efficiency 100 95 0 6 OUTPUT CURRENT (A) 95 60 3 OUTPUT CURRENT (A) MIC2164-2 12V to 3.3V Efficiency 100 VIN=5V 55 OUTPUT CURRENT (A) EFFICIENCY (%) 80 50 0 FEEDBACK VOLTAGE (V) 85 55 50 MIC2164-2 12V to 1.5V Efficiency 100 95 EFFICIENCY (%) EFFICIENCY (%) 100 MIC2164 12V to 3.3V Efficiency 6 16 20 0 3 6 9 12 15 OUTPUT CURRENT (A) M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Typical Characteristics (Continued) MIC2164 Switching Frequency vs. VIN 700 340 680 1090 1060 1030 1000 970 940 VHSD=12V VIN=5V 910 880 330 320 310 300 290 280 VHSD=12V 270 260 250 2 4 6 10 8 3.5 1120 1090 1060 1030 1000 970 VHSD=12V 910 880 4.5 5 4 4.5 600 580 560 520 3 5 VIN=5V 320 310 300 290 280 270 260 3 5.5 8 13 18 23 620 600 580 560 540 520 500 28 3 HSD VOLTAGE (V) 970 940 910 880 850 SWITCHING FREQUENCY (kHz) SWITCHING FREQUENCY (kHz) 680 1000 330 320 310 300 290 280 270 VIN=5V 260 250 23 28 -20 150 1120 135 CURRENT LIMIT THRESHOLD (mV) 1150 1030 1000 970 940 VIN=5V 0 40 60 80 TEMPERATURE (°C) September 2010 80 100 620 600 580 560 540 VIN=5V 520 120 -40 -20 0 20 100 120 40 60 80 100 120 TEMPERATURE (°C) Current Limit Threshold vs. Feedback Voltage Percentage Current Limit Threshold vs. Temperature 150 75 60 45 30 0 20 60 90 850 0 40 105 15 -20 20 120 880 -40 28 640 CURRENT LIMIT THRESHOLD (mV) MIC2164-3 Switching Frequency vs. Temperature 1060 23 660 TEMPERATURE (°C) 1090 18 500 -40 HSD VOLTAGE (V) 910 13 MIC2164-2 Switching Frequency vs. Temperature 340 18 8 HSD VOLTAGE (V) 1120 13 VIN=5V VOUT=2.5V 640 700 1030 5.5 660 MIC2164 Switching Frequency vs. Temperature VIN=5V 5 680 350 1090 4.5 700 330 MIC2164-3 Switching Frequency vs. VHSD 8 4 MIC2164-2 Switching Frequency vs. VHSD 1150 3 3.5 INPUT VOLTAGE (V) 340 INPUT VOLTAGE (V) 1060 VHSD=12V 540 5.5 250 850 3.5 620 MIC2164 Switching Frequency vs. VHSD SWITCHING FREQUENCY (kHz) SWITCHING FREQUENCY (kHz) 4 350 1150 3 640 INPUT VOLTAGE (V) MIC2164-3 Switching Frequency vs. VIN 940 660 500 3 OUTPUT CURRENT (A) SWITCHING FREQUENCY (kHz) 0 SWITCHING FREQUENCY (kHz) SWITCHING FREQUENCY (kHz) 350 1120 850 SWITCHING FREQUENCY (kHz) MIC2164-2 Switching Frequency vs. VIN 1150 SWITCHING FREQUENCY (kHz) SWITCHING FREQUENCY (kHz) MIC2164-3 Switching Frequency vs. Load VIN=5V 135 120 105 90 VFB=0.8V 75 VFB=0V 60 45 30 15 0 0 10 20 30 40 50 60 70 80 90 Feedback Voltage Percentage (%) 7 100 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Typical Characteristics (Continued) Quiescent Supply Current vs. Input Voltage 2 QUIESCENT SUPPLY CURRENT (mA) 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE (V) September 2010 8 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Functional Characteristics MIC2164-2 Load Transient L = 1.0μH Cout = 1100μF Vout (200mV/div) AC-coupled Vhsd = 12V Vin = 5V Vout = 3.3V Iout (5A/div) Time 200μs/div MIC2164-3 Load Transient L = 1.0μH Cout = 660μF Vout (200mV/div) AC-coupled Vhsd = 12V Vin = 5V Vout = 3.3V Iout (5A/div) Time 200μs/div September 2010 9 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Functional Characteristics (Continued) September 2010 10 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Functional Characteristics (continue) MIC2164-2 Output Voltage Ripple IL (5A/div) L = 1.0μH Cout = 1100μF VOUT (50mV/div) AC-coupled Vhsd = 12V Vin = 5V Vout = 3.3V Iout = 15A Time 2μs/div September 2010 11 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Functional Diagram Figure 1. MIC2164/-2/-3 Block Diagram September 2010 12 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C The maximum duty cycle is obtained from the 363ns TOFF(min): Functional Description The MIC2164/-2/-3 is an adaptive on-time synchronous buck controller family built for low cost and high performance. They are designed for a wide input voltage range from 3V to 28V and for high output power buck converters. An estimated-ON-time method is applied in MIC2164/-2/-3 to obtain a constant switching frequency and to simplify the control compensation. The overcurrent protection is implemented without the use of an external sense resistor. It includes an internal soft-start function which reduces the power supply input surge current at start-up by controlling the output voltage rise time. Dmax = VOUT VHSD × f sw (1) where VOUT is the output voltage, VHSD is the power stage input voltage, and fSW is the switching frequency (300kHz for MIC2164, 600kHz for MIC2164-2, and 1MHz for MIC2164-3). After ON-time period, the MIC2164/-2/-3 goes into the OFF-time period, in which DH pin is logic low and DL pin is logic high. The OFF-time period length is depending on the FB voltage in most cases. When the FB voltage decreases and the output of the gm amplifier is below 0.8V, then the ON-time period is trigger and the OFFtime period ends. If the OFF-time period decided by the FB voltage is less than the minimum OFF time TOFF(min), which is about 363ns typical, then the MIC2164/-2/-3 control logic will apply the TOFF(min) instead. TOFF(min) is required by the BST charging. September 2010 TS = 1− 363ns TS where Ts = 1/fSW. It is not recommended to use MIC2164/-2/-3 with a OFF time close to TOFF(min) at the steady state. Also, as VOUT increases, the internal ripple injection will increase and reduce the line regulation performance. Therefore, the maximum output voltage of the MIC2164/-2/-3 should be limited to 5.5V. If a higher output voltage is required, use the MIC2176 instead. Please refer to “Setting Output Voltage” subsection in “Application Information” for more details. The estimated-ON-time method results in a constant switching frequency in MIC2164/-2/-3. The actual ON time is varied with the different rising and falling time of the external MOSFETs. Therefore, the type of the external MOSFETs, the output load current, and the control circuitry power supply VIN will modify the actual ON time and the switching frequency. Also, the minimum TON results in a lower switching frequency in the high VHSD and low VOUT applications, such as 24V to 1.0V MIC2164-3 application. The minimum TON measured on the MIC2164 evaluation board is about 138ns. During the load transient, the switching frequency is changed due to the varying OFF time. To illustrate the control loop, the steady-state scenario and the load transient scenario are analyzed. For easy analysis, the gain of the gm amplifier is assumed to be 1. With this assumption, the inverting input of the error comparator is the same as the FB voltage. Figure 2 shows the MIC2164/-2/-3 control loop timing during the steady-state. During the steady-state, the gm amplifier senses the FB voltage ripple, which is proportional to the output voltage ripple and the inductor current ripple, to trigger the ON-time period. The ON time is predetermined by the estimation. The ending of OFF time is controlled by the FB voltage. At the valley of the FB voltage ripple, which is below than VREF, OFF period ends and the next ON-time period is triggered through the control logic circuitry. Theory of Operation The MIC2164/-2/-3 is a adaptive on-time buck controller family. Figure 1 illustrates the block diagram for the control loop. The output voltage variation will be sensed by the MIC2164/-2/-3 feedback pin FB via the voltage divider R1 and R2, and compared to a 0.8V reference voltage VREF at the error comparator through a low gain transconductance (gm) amplifier, the amplifier improves the MIC2164/-2/-3 converter output voltage regulation. If the FB voltage decreases and the output of the gm amplifier is below 0.8V, The error comparator will trigger the control logic and generate an ON-time period, in which DH pin is logic high and DL pin is logic low. The ON-time period length is predetermined by the “FIXED TON ESTIMATION” circuitry: TON(estimated) = TS − TOFF(min) 13 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C The MIC2164/-2/-3 family has its own stability concern: the FB voltage ripple should be in phase with the inductor current ripple and large enough to be sensed by the gm amplifier and the error comparator. The recommended minimum FB voltage ripple is 20mV. If a low ESR output capacitor is selected, then the FB voltage ripple may be too small to be sensed by the gm amplifier and the error comparator. Also, the output voltage ripple and the FB voltage ripple are not in phase with the inductor current ripple if the ESR of the output capacitor is very low. Therefore, the ripple injection is required for a low ESR output capacitor. Please refer to “Ripple Injection” subsection in “Application Information” for more details about the ripple injection. Soft-Start Soft-start reduces the power supply input surge current at startup by controlling the output voltage rise time. The input surge appears while the output capacitor is charged up. A slower output rise time will draw a lower input surge current. MIC2164/-2/-3 implements an internal digital soft-start by making the 0.8V reference voltage VREF ramp from 0 to 100% in about 6ms with a 9.7mV step. Therefore, the output voltage is controlled to increase slowly by a staircase VREF ramp. Once the soft-start ends, the related circuitry is disabled to reduce the current consumption. VIN should be powered up no earlier than VHSD to make the soft-start function behavior correctly. Figure 2. MIC2164/-2/-3 Control Loop Timing Figure 3 shows the load transient scenario of the MIC2164/-2/-3 converter. The output voltage drops due to the sudden load increasing, which would cause the FB voltage to be less than VREF. This will cause the error comparator to trigger ON-time period. At the end of the ON-time period, a minimum OFF time TOFF(min) is generated to charge BST since the FB voltage is still below the VREF. Then, the next ON-time period is triggered due to the low FB voltage. Therefore, the switching frequency changes during the load transient. With the varying duty cycle and switching frequency, the output recovery time is fast and the output voltage deviation is small in MIC2164/-2/-3 converter. Current Limit The MIC2164/-2/-3 uses the RDS(ON) of the low-side power MOSFET to sense over-current conditions. The lower-side MOSFET is used because it displays much lower parasitic oscillations during switching then the high-side MOSFET. Using the low-side MOSFET RDS(ON) as a current sense is an excellent method for circuit protection. This method will avoid adding cost, board space and power losses taken by discrete current sense resistors. In each switching cycle of the MIC2164/-2/-3 converter, the inductor current is sensed by monitoring the low-side MOSFET in the OFF period. The sensed voltage is compared with a current-limit threshold voltage VCL after a blanking time of 150ns. If the sensed voltage is over VCL, which is 130mV typical at 0.8V feedback voltage, the MIC2164/-2/-3 turns off the high-side MOSFET and a soft-start sequence is trigged. This mode of operation is called the “hiccup mode” and its purpose is to protect the down stream load in case of a hard short. The current limit threshold VCL has a fold back characteristics related to the FB voltage. Please refer to the “Typical Characteristics” for the curve of VCL vs. FB voltage. The circuit in Figure 4 illustrates the MIC2164/-2/-3 current limiting circuit. Figure 3. MIC2164/-2/-3 Load-Transient Response Unlike the current-mode control, MIC2164/-2/-3 uses the output voltage ripple, which is proportional to the inductor current ripple if the ESR of the output capacitor is large enough, to trigger an ON-time period. The predetermined ON time makes MIC2164/-2/-3 control loop has the advantage as the adaptive on-time mode control. Therefore, the slope compensation, which is necessary for the current-mode control, is not required in the MIC2164/-2/-3 family. September 2010 14 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C MOSFET Gate Drive The MIC2164/-2/-3 high-side drive circuit is designed to switch an N-Channel MOSFET. The block diagram of Figure 1 shows a bootstrap circuit, consisting of D1 (a Schottky diode is recommended) and CBST. This circuit supplies energy to the high-side drive circuit. Capacitor CBST is charged while the low-side MOSFET is on and the voltage on the LX pin is approximately 0V. When the high-side MOSFET driver is turned on, energy from CBST is used to turn the MOSFET on. As the high-side MOSFET turns on, the voltage on the LX pin increases to approximately VHSD. Diode D1 is reversed biased and CBST floats high while continuing to keep the high-side MOSFET on. The bias current of the high-side driver is less than 10mA so a 0.1μF to 1μF is sufficient to hold the gate voltage with minimal droop for the power stroke (high-side switching) cycle, i.e. ΔBST = 10mA x 3.33μs/0.1μF = 333mV for MIC2164. When the low-side MOSFET is turned back on, CBST is recharged through D1. A small resistor RG, which is in series with CBST, can slow down the turn-on time of the high-side N-channel MOSFET. The drive voltage is derived from the supply voltage VIN. The nominal low-side gate drive voltage is VIN and the nominal high-side gate drive voltage is approximately VIN – VDIODE, where VDIODE is the voltage drop across D1. An approximate 30ns delay between the high-side and lowside driver transitions is used to prevent current from simultaneously flowing unimpeded through both MOSFETs. Figure 4. MIC2164/-2/-3 Current Limiting Circuit Using the typical VCL value of 130mV, the current limit value is roughly estimated as: ICL ≈ 130mV R DS(ON) For designs where the current ripple is significant compared to the load current IOUT, or for low duty cycle operation, calculating the current limit ICL should take into account that one is sensing the peak inductor current and that there is a blanking delay of approximately 150ns. ICL = V * TDLY ΔIL(pp) 130mV + OUT − R DS(ON) L 2 ΔIL(pp) = VOUT ⋅ (1 − D) f SW ⋅L (2) (3) where VOUT = The output voltage TDLY = Current limit blanking time, 150ns typical ΔIL(pp) = Inductor current ripple peak-to-peak value D = Duty Cycle fSW = Switching frequency The MOSFET RDS(ON) varies 30 to 40% with temperature; therefore, it is recommended to add a 50% margin to ICL in the above equation to avoid false current limiting due to increased MOSFET junction temperature rise. It is also recommended to connect LX pin directly to the drain of the low-side MOSFET to accurately sense the MOSFETs RDS(ON). September 2010 15 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C The low-side MOSFET is turned on and off at VDS = 0 because an internal body diode or external freewheeling diode is conducting during this time. The switching loss for the low-side MOSFET is usually negligible. Also, the gate-drive current for the low-side MOSFET is more accurately calculated using CISS at VDS = 0 instead of gate charge. For the low-side MOSFET: Application Information MOSFET Selection The MIC2164/-2/-3 controller works from power stage input voltages of 3V to 28V and has an external 3V to 5.5V VIN to provide power to turn the external N-Channel power MOSFETs for the high- and low-side switches. For applications where VIN < 5V, it is necessary that the power MOSFETs used are sub-logic level and are in full conduction mode for VGS of 2.5V. For applications when VIN > 5V; logic-level MOSFETs, whose operation is specified at VGS = 4.5V must be used. There are different criteria for choosing the high-side and low-side MOSFETs. These differences are more significant at lower duty cycles such as 12V to 1.8V conversion. In such an application, the high-side MOSFET is required to switch as quickly as possible to minimize transition losses, whereas the low-side MOSFET can switch slower, but must handle larger RMS currents. When the duty cycle approaches 50%, the current carrying capability of the high-side MOSFET starts to become critical. It is important to note that the on-resistance of a MOSFET increases with increasing temperature. A 75°C rise in junction temperature will increase the channel resistance of the MOSFET by 50% to 75% of the resistance specified at 25°C. This change in resistance must be accounted for when calculating MOSFET power dissipation and in calculating the value of current limit. Total gate charge is the charge required to turn the MOSFET on and off under specified operating conditions (VDS and VGS). The gate charge is supplied by the MIC2164/-2/-3 gate-drive circuit. At 300kHz switching frequency and above, the gate charge can be a significant source of power dissipation in the MIC2164/2/-3. At low output load, this power dissipation is noticeable as a reduction in efficiency. The average current required to drive the high-side MOSFET is: IG[high-side] (avg) = Q G × f SW IG[low -side] (avg) = C ISS × VGS × f SW (5) Since the current from the gate drive comes from the VIN, the power dissipated in the MIC2164/-2/-3 due to gate drive is: PGATEDRIVE = VIN .(IG[high-side] (avg) + IG[low -side] (avg)) (6) A convenient figure of merit for switching MOSFETs is the on resistance times the total gate charge RDS(ON) × QG. Lower numbers translate into higher efficiency. Low gate-charge logic-level MOSFETs are a good choice for use with the MIC2164/-2/-3. Also, the RDS(ON) of the lowside MOSFET will determine the current limit value. Please refer to “Current Limit” subsection is “Functional Description” for more details. Parameters that are important to MOSFET switch selection are: • Voltage rating • On-resistance • Total gate charge The voltage ratings for the high-side and low-side MOSFETs are essentially equal to the power stage input voltage VHSD. A safety factor of 20% should be added to the VDS(max) of the MOSFETs to account for voltage spikes due to circuit parasitic elements. The power dissipated in the MOSFETs is the sum of the conduction losses during the on-time (PCONDUCTION) and the switching losses during the period of time when the MOSFETs turn on and off (PAC). (4) where: IG[high-side](avg) = Average high-side MOSFET gate current QG = Total gate charge for the high-side MOSFET taken from the manufacturer’s data sheet for VGS = VIN. fSW = Switching Frequency PSW = PCONDUCTION + PAC (7) 2 PCONDUCTION = ISW(RMS) * R DS(ON) (8) PAC = PAC(off ) + PAC(on) (9) where: RDS(ON) = on-resistance of the MOSFET switch D = Duty Cycle = VOUT / VHSD September 2010 16 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Making the assumption that the turn-on and turn-off transition times are equal; the transition times can be approximated by: tT The peak-to-peak inductor current ripple is: ΔIL(PP ) = C × VIN + C OSS × VHSD = ISS IG (10) IL(PK) = IOUT(max) + 0.5 × ΔIL(PP) (11) IL(RMS) = IOUT(max)2 + ) (15) 12 PINDUCTORCu=IL(RMS)2 × RWINDING (12) (16) The resistance of the copper wire, RWINDING, increases with the temperature. The value of the winding resistance used should be at the operating temperature. where: fSW = switching frequency 20% = ratio of AC ripple current to DC output current VHSD(max) = maximum power stage input voltage September 2010 ΔIL(PP)2 Maximizing efficiency requires both the proper selection of core material and the minimizing of the winding resistance. The high frequency operation of the MIC2164/-2/-3 requires the use of ferrite materials for all but the most cost sensitive applications. Lower cost iron powder cores may be used but the increase in core loss will reduce the efficiency of the power supply. This is especially noticeable at low output power. The winding resistance decreases efficiency at the higher output current levels. The winding resistance must be minimized although this usually comes at the expense of a larger inductor. The power dissipated in the inductor is equal to the sum of the core and copper losses. At higher output loads, the core losses are usually insignificant and can be ignored. At lower output currents, the core losses can be a significant contributor. Core loss information is usually available from the magnetics vendor. Copper loss in the inductor is calculated by the equation below: Inductor Selection Values for inductance, peak, and RMS currents are required to select the output inductor. The input and output voltages and the inductance value determine the peak-to-peak inductor ripple current. Generally, higher inductance values are used with higher input voltages. Larger peak-to-peak ripple currents will increase the power dissipation in the inductor and MOSFETs. Larger output ripple currents will also require more output capacitance to smooth out the larger ripple current. Smaller peak-to-peak ripple currents require a larger inductance value and therefore a larger and more expensive inductor. A good compromise between size, loss and cost is to set the inductor ripple current to be equal to 20% of the maximum output current. The inductance value is calculated by the equation below: ( (14) The RMS inductor current is used to calculate the I2R losses in the inductor. where: tT = Switching transition time VD = Body diode drop (0.5v) fSW = Switching Frequency The high-side MOSFET switching losses increase with the switching frequency and the input voltage VHSD. The low-side MOSFET switching losses are negligible and can be ignored for these calculations. VOUT × VHSD(max) − VOUT L= VHSD(max) × f SW × 20% × IOUT(max) (13) VHSD(max) × f SW × L The peak inductor current is equal to the average output current plus one half of the peak-to-peak inductor current ripple. where: CISS and COSS are measured at VDS = 0 IG = gate-drive current The total high-side MOSFET switching loss is: PAC = (VHSD + VD ) × IPK × t T × f SW VOUT × ( VHSD(max) − VOUT ) 17 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C The voltage rating of the capacitor should be twice the output voltage for a tantalum and 20% greater for aluminum electrolytic or OS-CON. The output capacitor RMS current is calculated below: RWINDING = RWINDING(20°c) × (1 + 0.0042 × (TH – T20°C)) (17) where: TH = temperature of wire under full load T20°C = ambient temperature RWINDING(20°C) = room temperature winding resistance (usually specified by the manufacturer) ICOUT (RMS) = Output Capacitor Selection The type of the output capacitor is usually determined by its ESR (equivalent series resistance). Voltage and RMS current capability are two other important factors for selecting the output capacitor. Recommended capacitors are tantalum, low-ESR aluminum electrolytic, OS-CON and POSCAPS. The output capacitor’s ESR is usually the main cause of the output ripple. The output capacitor ESR also affects the control loop from a stability point of view. The maximum value of ESR is calculated: ESR COUT ≤ ΔVOUT(pp) 2 PDISS(COUT ) = ICOUT (RMS) ⋅ ESR COUT ΔVOUT(pp) ΔVIN = IL(PK ) × ESR CIN ) where: D = duty cycle COUT = output capacitance value fSW = switching frequency As described in the “Theory of Operation” subsection in “Functional Description”, MIC2164/-2/-3 requires at least 20mV peak-to-peak ripple at the FB pin to make the gm amplifier and the error comparator to behavior properly. Also, the output voltage ripple should be in phase with the inductor current. Therefore, the output voltage ripple caused by the output capacitor COUT should be much smaller than the ripple caused by the output capacitor ESR. If low ESR capacitors are selected as the output capacitors, such as ceramic capacitors, a ripple injection method is applied to provide the enough FB voltage ripples. Please refer to the “Ripple Injection” subsection for more details. September 2010 (22) The input capacitor must be rated for the input current ripple. The RMS value of input capacitor current is determined at the maximum output current. Assuming the peak-to-peak inductor current ripple is low: ΔIL(PP) ⎞ ⎛ 2 ⎟ + ΔIL(PP) ⋅ ESR C = ⎜⎜ OUT ⎟ ⎝ C OUT ⋅ f SW ⋅ 8 ⎠ (19) ( (21) Input Capacitor Selection The input capacitor for the power stage input VHSD should be selected for ripple current rating and voltage rating. Tantalum input capacitors may fail when subjected to high inrush currents, caused by turning the input supply on. A tantalum input capacitor’s voltage rating should be at least two times the maximum input voltage to maximize reliability. Aluminum electrolytic, OS-CON, and multilayer polymer film capacitors can handle the higher inrush currents without voltage derating. The input voltage ripple will primarily depend upon the input capacitor’s ESR. The peak input current is equal to the peak inductor current, so: where: ΔVOUT(pp) = peak-to-peak output voltage ripple ΔIL(PP) = peak-to-peak inductor current ripple The total output ripple is a combination of the ESR and output capacitance. The total ripple is calculated below: 2 (20) 12 The power dissipated in the output capacitor is: (18) ΔIL(PP) ΔIL(PP) ICIN(RMS ) ≈ IOUT(max) × D × (1 − D ) (23) The power dissipated in the input capacitor is: PDISS(CIN) = ICIN(RMS)2×ESRCIN 18 (24) M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C External Schottky Diode (Optional) An external freewheeling diode, which is generally not necessary, can be used to keep the inductor current flow continuous while both MOSFETs are turned off. This dead time prevents current from flowing unimpeded through both MOSFETs and is typically 30ns. The diode conducts twice during each switching cycle. Although the average current through this diode is small, the diode must be able to handle the peak current. ID(avg) = IOUT ⋅ 2 ⋅ 30ns ⋅ f SW Ripple Injection The minimum FB voltage ripple requested by the MIC2164/-2/-3 gm amplifier and error comparator is 20mV (100mV maximum). However, the output voltage ripple is generally designed as 1% to 2% of the output voltage. For a low output voltage, such as 1V output, the output voltage ripple is only 10mV to 20mV, and the FB voltage ripple is less than 20mV. If the FB voltage ripple is so small that the gm amplifier and error comparator could not sense it, then the MIC2164/-2/-3 will lose control and the output voltage will not be regulated. In order to have some amount of FB voltage ripple, the ripple injection method is applied for low output voltage ripple applications. The applications are divided into three situations according to the amount of the FB voltage ripple: 1) Enough ripple at the FB voltage due to the large ESR of the output capacitors. As shown in Figure 5a, the converter is stable without any adding in this situation. The FB voltage ripple is: (25) The reverse voltage requirement of the diode is: VDIODE(rrm) = VHSD The power dissipated by the Schottky diode is: PDIODE = ID(avg) × VF (26) ΔVFB(pp) = where, VF = forward voltage at the peak diode current. The external Schottky diode is not necessary for the circuit operation since the low-side MOSFET contains a parasitic body diode. The external diode will improve efficiency and decrease the high frequency noise. If the MOSFET body diode is then used, it must be rated to handle the peak and average current. The body diode has a relatively slow reverse recovery time and a relatively high forward voltage drop. The power lost in the diode is proportional to the forward voltage drop of the diode. As the high-side MOSFET starts to turn on, the body diode becomes a short circuit for the reverse recovery period, dissipating additional power. The diode recovery and the circuit inductance will cause ringing during the high-side MOSFET turn-on. An external Schottky diode conducts at a lower forward voltage preventing the body diode in the MOSFET from turning on. The lower forward voltage drop dissipates less power than the body diode. The lack of a reverse recovery mechanism in a Schottky diode causes less ringing and less power loss. Depending upon the circuit components and operating conditions, an external Schottky diode will give a ½ to 1% improvement in efficiency. September 2010 R2 ⋅ ESR COUT ⋅ ΔIL (pp) R1 + R2 (27) where ΔIL(pp) is the peak-to-peak value of the inductor current ripple. 2) Inadequate ripple at the FB voltage due to the small ESR of the output capacitors. The output voltage ripple is fed into the FB pin through a feedforward capacitor Cff in this situation, as shown in Figure 5b. The typical Cff value is between 1nF to 100nF. With the feedforward capacitor, the FB voltage ripple is very close to the output voltage ripple: ΔVFB(pp) ≈ ESR ⋅ ΔIL (pp) (28) 3) Invisible ripple at the FB voltage is due to the very low ESR of the output capacitors. 19 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C In the formula (29) and (30), it is assumed that the time constant associated with Cff must be much greater than the switching period: 1 T = << 1 fsw × τ τ Figure 5a. Enough Ripple at FB If the voltage divider resistors R1 and R2 are in the kΩ range, a Cff of 1nF to 100nF can easily satisfy the large time constant consumption. Also, a 100nF injection capacitor Cinj is used in order to be considered as short for a wide range of the frequencies. The process of sizing the ripple injection resistor and capacitors is: Step 1. Select Cff to feed all output ripples into the feedback pin and make sure the large time constant assumption is satisfied. Typical choice of Cff is 1nF to 100nF if R1 and R2 are in kΩ range. Step 2. Select Rinj according to the expected feedback voltage ripple. According to the equation (30): Figure 5b. Inadequate Ripple at FB K div = ΔVFB(pp ) VHSD ⋅ fSW ⋅ τ D ⋅ (1 − D) (31) Then the value of Rinj is obtained as: R inj = (R1 // R2) ⋅ ( Figure 5c. Invisible Ripple at FB In this situation, the output voltage ripple is less than 20mV. Therefore, additional ripple is injected into the FB pin from the switching node LX via a resistor Rinj and a capacitor Cinj, as shown in Figure 5c. The injected ripple is: ΔVFB(pp) = VHSD × K div × D × (1- D) × K div = 1 f SW × τ R1//R2 Rinj + R1//R2 1 K div − 1) (32) Step 3. Select Cinj as 100nF, which could be considered as short for a wide range of the frequencies. (29) (30) where VHSD = Power stage input voltage at HSD pin D = Duty Cycle fSW = switching frequency τ = (R1// R2 // Rinj) ⋅ Cff September 2010 20 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Setting Output Voltage The MIC2164/-2/-3 requires two resistors to set the output voltage, as shown in Figure 6: In addition to the external ripple injection added at the FB pin, internal ripple injection is added at the inverting input of the comparator inside the MIC2164/-2/-3, as shown in Figure 7. The inverting input voltage VINJ is clamped to 1.2V. As VOUT is increased, the swing of VINJ will be clamped. The clamped VINJ reduces the line regulation because it is reflected back as a DC error on the FB terminal. Therefore, the maximum output voltage of the MIC2164/-2/-3 should be limited to 5.5V to avoid this problem. If a higher output voltage is required, use the MIC2176 instead. Figure 6. Voltage-Divider Configuration The output voltage is determined by the equation: VOUT = VREF × (1 + R1 ) R2 (33) Figure 7. Internal Ripple Injection where VREF = 0.8V. A typical value of R1 can be between 3kΩ and 10kΩ. If R1 is too large, it may allow noise to be introduced into the voltage feedback loop. If R1 is too small, it will decrease the efficiency of the power supply, especially at light loads. Once R1 is selected, R2 can be calculated using: R2 = September 2010 VREF × R1 VOUT − VREF (34) 21 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C capacitor is very critical. Connections must be made with wide trace. PCB Layout Guideline Warning!!! To minimize EMI and output noise, follow these layout recommendations. PCB Layout is critical to achieve reliable, stable and efficient performance. A ground plane is required to control EMI and minimize the inductance in power, signal and return paths. The following guidelines should be followed to insure proper operation of the MIC2164/-2/-3 converter. Inductor IC • Keep the inductor connection to the switch node (LX) short. • Do not route any digital lines underneath or close to the inductor. • Keep the switch node (LX) away from the feedback (FB) pin. • The LX pin should be connected directly to the drain of the low-side MOSFET to accurate sense the voltage across the low-side MOSFET. To minimize noise, place a ground plane underneath the inductor. • Place the IC and MOSFETs close to the point of load (POL). • Use fat traces to route the input and output power lines. • • Signal and power grounds should be kept separate and connected at only one location. Output Capacitor • Use a wide trace to connect the output capacitor ground terminal to the input capacitor ground terminal. • Phase margin will change as the output capacitor value and ESR changes. Contact the factory if the output capacitor is different from what is shown in the BOM. • The feedback trace should be separate from the power trace and connected as close as possible to the output capacitor. Sensing a long high current load trace can degrade the DC load regulation. Input Capacitor • Place the HSD input capacitor next. • Place the HSD input capacitors on the same side of the board and as close to the MOSFETs as possible. • Keep both the HSD and PGND connections short. • Place several vias to the ground plane close to the HSD input capacitor ground terminal. • Use either X7R or X5R dielectric input capacitors. Do not use Y5V or Z5U type capacitors. • Do not replace the ceramic input capacitor with any other type of capacitor. Any type of capacitor can be placed in parallel with the input capacitor. • If a Tantalum input capacitor is placed in parallel with the input capacitor, it must be recommended for switching regulator applications and the operating voltage must be derated by 50%. • Schottky Diode (Optional) In “Hot-Plug” applications, a Tantalum or Electrolytic bypass capacitor must be used to limit the overvoltage spike seen on the input supply with power is suddenly applied. • An additional Tantalum or Electrolytic bypass input capacitor of 22uF or higher is required at the input power connection. • The 1µF and 0.1µF capacitors, which connect to the VIN terminal, must be located right at the IC. The VIN terminal is very noise sensitive and placement of the September 2010 • Place the Schottky diode on the same side of the board as the MOSFETs and HSD input capacitor. • The connection from the Schottky diode’s Anode to the input capacitors ground terminal must be as short as possible. • The diode’s cathode connection to the switch node (LX) must be keep as short as possible. RC Snubber • 22 Place the RC snubber on the same side of the board and as close to the MOSFETs as possible. M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Evaluation Board Schematics Figure 8. Schematic of MIC2164 20A Evaluation Board September 2010 23 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Bill of Materials Item C1 Part Number EPCOS 222215095001E3 Vishay C6,C9,C10, C14,C16 C7 GRM32ER61C226KE20L C11 C12 C13,C15 C17 L1 Q1,Q4 Q2,Q3 Murata(4) TDK 0805ZD105KAT2A AVX(3) Murata(4) TDK 0805ZC225MAT2A AVX(3) Murata(4) 2 0.1µF Ceramic Capacitor, X7R, Size 0603, 50V 5 1µF Ceramic Capacitor, X5R, Size 0805, 10V 1 2.2µF Ceramic Capacitor, X7R, Size 0805, 10V 1 1nF Ceramic Capacitor, X7R, Size 0603, 50V 1 22nF Ceramic Capacitor, X7R, Size 0603, 50V 1 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V 2 1000µF Aluminum Capacitor, 16V 1 Small Signal Schottky Diode 1 (5) C2012X7R1A225K TDK 06035C102KAT2A AVX(3) Murata(4) (5) C1608X7R1H102K TDK 06035C223KAZ2A AVX(3) GRM188R71H223K Murata(4) (5) C1608X7R1H223K TDK 12106D107MAT2A AVX(3) GRM32ER60J107ME20L Murata(4) 16ME1000WG SANYO(6) Diodes Inc (7) SD103BWS Vishay(2) CDEP147NP-1R5M Sumida(8) FDS8672S 22µF Ceramic Capacitor, X5R, Size 1210, 16V (5) C2012X5R1A105K FDMS7672 1 (5) C1608X7R1H104K GRM188R71H102KA01D 220µF Aluminum Capacitor, SMD, 35V (5) AVX(3) SD103BWS-7 D1 Murata(4) 06035C104KAT2A GRM21BR71A225KA01L Qty. AVX(3) TDK GRM219R61A105KC01D C8 (2) C3225X5R1C226K GRM188R71H104KA93D Description (1) B41125A7227M 1210YD226KAT2A C2,C3 Manufacturer Fairchild 1.5µH Inductor, 27.2A Saturation Current 1 (9) 30V N-Channel MOSFET 6.9mΩ RDS(ON) @ 4.5V 2 (9) 30V N-Channel MOSFET 7mΩ RDS(ON) @ 4.5V 2 Fairchild Notes: 1. EPCOS: www.epcos.com. 2. Vishay: www.vishay.com. 3. AVX: www.avx.com. 4. Murata: www.murata.com. 5. TDK: www.tdk.com. 6. Sanyo: www.sanyo.com. 7. Diodes Inc: www.diodes.com. 8. Sumida: www.sumida.com. 9. Fairchild: www.fairchildsemi.com. September 2010 24 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Bill of Materials (Continued) Item R1 Part Number CRCW06032R21FKEA Manufacturer Description (2) 2.21Ω Resistor, Size 0603, 1% (2) Vishay/Dale Qty. 1 R2 CRCW06031R21FKEA Vishay/Dale 1.21Ω Resistor, Size 0603, 1% 1 R3,R4 CRCW060310K0FKEA Vishay/Dale(2) 10kΩ Resistor, Size 0603, 1% 2 R5 CRCW060320R0FKEA Vishay/Dale(2) 20Ω Resistor, Size 0603, 1% 1 CRCW06033K24FKEA (2) 3.24kΩ Resistor, Size 0603, 1% 1 (10) 300kHz Buck Controller 1 (10) LDO 1 R6 U1 (11) U2 MIC2164YMM MIC5233-5.0YM5 Vishay/Dale MICREL INC MICREL INC Notes: 10. Micrel, Inc.: www.micrel.com. 11. Optional: Required if 5V supply is not available in the system. September 2010 25 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C PCB Layout Recommendations Figure 9. MIC2164 20A Evaluation Board Top Layer Figure 10. MIC2164 20A Evaluation Board Bottom Layer September 2010 26 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C PCB Layout Recommendations (Continued) Figure 11. MIC2164 20A Evaluation Board Mid-Layer 1 Figure 12. MIC2164 20A Evaluation Board Mid-Layer 2 September 2010 27 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Application Schematics and Bill of Materials Figure 13. MIC2164 12V to 3.3V @ 20A Buck Converter September 2010 28 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Bill of Materials (MIC2164 12V to 3.3V @ 20A) Item C1, C8, C17, C19 Part Number 06035C104KAT C2 0805ZD225MAT C3 222215095001 C4, C5, C6 1210YD226MAT C9 0805ZD105KAT C10 C11 C12 C15 D1 06035C223KAT 16ME1000WGL 12106D107MAT 06035C102KAT SD103BWS L1 CDEP147NP-1R5M Manufacturer (1) AVX Description Qty. 0.1µF Ceramic Capacitor, X7R, Size 0603, 50V (1) AVX Vishay(2) AVX(1) 4 2.2µF Ceramic Capacitor, X5R, Size 0805, 10V 1 220µF Aluminum Capacitor, SMD, 35V 1 22µF Ceramic Capacitor, X5R, Size 1210, 16V 3 (1) 1µF Ceramic Capacitor, X5R, Size 0805, 10V 1 (1) 22nF Ceramic Capacitor, X7R, Size 0603, 50V 1 AVX AVX Sanyo (3) 1000µF Aluminum Capacitor, 16V 1 (1) 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V 1 (1) 1nF Ceramic Capacitor, X7R, Size 0603, 50V 1 Small Signal Schottky Diode 1 1.5µH Inductor, 27.2A Saturation Current 1 AVX AVX (2) Vishay Sumida (4) (5) Q1, Q4 FDMS7672 Fairchild 30V N-Channel MOSFET 6.9mΩ RDS(ON) @ 4.5V 2 Q2, Q3 FDS8672S Fairchild(5) 30V N-Channel MOSFET 7mΩ RDS(ON) @ 4.5V 2 R1 CRCW06032R21FKEY3 Vishay Dale(2) 2.21Ω Resistor, Size 0603, 1% 1 CRCW06031R21FKEY3 (2) 1.21Ω Resistor, Size 0603, 1% 1 (2) 10k Resistor, Size 0603, 1% 2 (2) 3.24k Resistor, Size 0603 1% 1 (6) 300kHz Buck Controller 1 (6) LDO 1 R5 R6, R9 R15 U1 CRCW06031002FKEY3 CRCW06033241FKEY3 MIC2164YMM U2 MIC5233-5.0YM5 Vishay Dale Vishay Dale Vishay Dale Micrel. Inc. Micrel. Inc. Notes: 1. AVX: www.avx.com. 2. Vishay: www.vishay.com. 3. Sanyo: www.sanyo.com. 4. Sumida: www.sumida.com. 5. Fairchild: www.fairchildsemi.com. 6. Micrel, Inc: www.micrel.com. September 2010 29 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Figure 14. MIC2164 12V to 1.8V @ 10A Buck Converter September 2010 30 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Bill of Materials (MIC2164 12V to 1.8V @ 10A) Item C1, C8, C17, C19 Part Number 06035C104KAT C2 0805ZD225MAT C3 222215095001 C4, C5 1210YD106MAT C9 0805ZD105KAT C10 C11 C12 C15 D1 06035C223KAT 6SEPC560MX 12106D107MAT 06035C102KAT SD103BWS L1 CDEP105-2R0MC-32 Manufacturer (1) AVX Description Qty. 0.1µF Ceramic Capacitor, X7R, Size 0603, 50V (1) AVX Vishay(2) AVX(1) 4 2.2µF Ceramic Capacitor, X5R, Size 0805, 10V 1 220µF Aluminum Capacitor, SMD, 35V 1 10µF Ceramic Capacitor, X5R, Size 1210, 16V 2 (1) 1µF Ceramic Capacitor, X5R, Size 0805, 10V 1 (1) 22nF Ceramic Capacitor, X7R, Size 0603, 50V 1 AVX AVX Sanyo (3) 560µF OSCON Capacitor, 6.3V 1 (1) 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V 1 (1) 1nF Ceramic Capacitor, X7R, Size 0603, 50V 1 AVX AVX (2) Vishay Sumida Small Signal Schottky Diode 1 (4) 2.0µH Inductor, 15.8A Saturation Current 1 (5) Q1, Q2 FDS7764A 30V N-Channel MOSFET 7.5mΩ RDS(ON) @ 4.5V 2 R1 CRCW06032R21FKEY3 Vishay Dale(2) 2.21Ω Resistor, Size 0603, 1% 1 CRCW06031R21FKEY3 (2) 1.21Ω Resistor, Size 0603, 1% 1 (2) 10k Resistor, Size 0603, 1% 2 (2) 8.06k Resistor, Size 0603, 1% 1 (6) 300kHz Buck Controller 1 (6) LDO 1 R5 R6, R9 R15 U1 CRCW06031002FKEY3 CRCW06038061FKEY3 MIC2164YMM U2 MIC5233-5.0YM5 Fairchild Vishay Dale Vishay Dale Vishay Dale Micrel. Inc. Micrel. Inc. Notes: 1. AVX: www.avx.com. 2. Vishay: www.vishay.com. 3. Sanyo: www.sanyo.com. 4. Sumida: www.sumida.com. 5. Fairchild: www.fairchildsemi.com. 6. Micrel, Inc: www.micrel.com. September 2010 31 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Figure 15. MIC2164 12V to 1.0V @ 5A Buck Converter September 2010 32 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Bill of Materials (MIC2164 12V to 1.0V @ 5A) Item Part Number C1, C8, C17, C19 06035C104KAT C2 0805ZD225MAT C3 222215095001 C4 1210YD106MAT C9 Manufacturer Description (1) AVX 0.1µF Ceramic Capacitor, X7R, Size 0603, 50V 4 2.2µF Ceramic Capacitor, X5R, Size 0805, 10V 1 220µF Aluminum Capacitor, SMD, 35V 1 AVX 10µF Ceramic Capacitor, X5R, Size 1210, 16V 1 0805ZD105KAT AVX 1µF Ceramic Capacitor, X5R, Size 0805, 10V 1 C10 06035C223KAT AVX 22nF Ceramic Capacitor, X7R, Size 0603, 50V 1 C11, C12, C13 12106D107MAT AVX 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V 3 C15 06035C102KAT AVX 1nF Ceramic Capacitor, X7R, Size 0603, 50V 1 D1 SD103BWS Small Signal Schottky Diode 1 3.8µH Inductor, 6A Saturation Current 1 Dual 30V N-Channel MOSFET 17mΩ RDS(ON) @ 4.5V 1 L1 CDRH104RNP-3R8 Q1 FDS6910 AVX Qty. Vishay(2) Vishay Sumida (4) Fairchild (5) (2) R1 CRCW06032R21FKEY3 Vishay Dale 2.21Ω Resistor, Size 0603, 1% 1 R5 CRCW06031R21FKEY3 Vishay Dale 1.21Ω Resistor, Size 0603, 1% 1 R6, R9 CRCW06031002FKEY3 Vishay Dale 10k Resistor, Size 0603, 1% 2 R15 CRCW06034022FKEY3 Vishay Dale 40.2k Resistor, Size 0603, 1% 1 300kHz Buck Controller 1 LDO 1 U1 MIC2164YMM U2 MIC5233-5.0YM5 (6) Micrel. Inc. Micrel. Inc. Notes: 1. AVX: www.avx.com. 2. Vishay: www.vishay.com. 3. Sanyo: www.sanyo.com. 4. Sumida: www.sumida.com. 5. Fairchild: www.fairchildsemi.com. 6. Micrel, Inc: www.micrel.com. September 2010 33 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Figure 16. MIC2164-2 12V to 3.3V @ 15A Buck Converter September 2010 34 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Bill of Materials (MIC2164-2 12V to 3.3V @ 15A) Item Part Number C1, C8, C17, C19 06035C104KAT C2 0805ZD225MAT C3 222215095001 C4, C5 1210YD226MAT C9 0805ZD105KAT C10 C11 C12 C15 D1 06035C472KAT 16ME1000WGL 12106D107MAT 06035C102KAT SD103BWS L1 HCP1305-1R0 Manufacturer 0.1µF Ceramic Capacitor, X7R, Size 0603, 50V 2.2µF Ceramic Capacitor, X5R, Size 0805, 10V 1 220µF Aluminum Capacitor, SMD, 35V 1 AVX Vishay(2) AVX(1) 22µF Ceramic Capacitor, X5R, Size 1210, 16V 2 1µF Ceramic Capacitor, X5R, Size 0805, 10V 1 (1) 4.7nF Ceramic Capacitor, X7R, Size 0603, 50V 1 AVX AVX Sanyo (3) 1000µF Aluminum Capacitor, 16V 1 (1) 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V 1 (1) 1nF Ceramic Capacitor, X7R, Size 0603, 50V 1 Small Signal Schottky Diode 1 AVX AVX (2) Vishay (4) Cooper Bussmann 1.0µH Inductor, 29A DC Current 1 (5) 30V N-Channel MOSFET 6.9mΩ RDS(ON) @ 4.5V 1 30V N-Channel MOSFET 7.0mΩ RDS(ON) @ 4.5V 2 (2) 2.21Ω Resistor, Size 0603, 1% 1 (2) 1.21Ω Resistor, Size 0603, 1% 1 (2) 10k Resistor, Size 0603, 1% 1 (2) 4.02k Resistor, Size 0603, 1% 1 (2) 3.24k Resistor, Size 0603 1% 1 Micrel. Inc. (6) 600kHz Buck Controller 1 Micrel. Inc. (6) LDO 1 FDMS7672 Fairchild FDS8874 Fairchild(5) R5 CRCW06031R21FKEY3 R6 CRCW06031002FKEY3 R9 CRCW06034021FKEY3 R15 U1 CRCW06033241FKEY3 MIC2164-2YMM U2 MIC5233-5.0YM5 4 (1) Q1 CRCW06032R21FKEY3 Qty. (1) AVX Q2, Q3 R1 Description (1) Vishay Dale Vishay Dale Vishay Dale Vishay Dale Vishay Dale Notes: 1. AVX: www.avx.com. 2. Vishay: www.vishay.com. 3. Sanyo: www.sanyo.com. 4. Sumida: www.sumida.com. 5. Fairchild: www.fairchildsemi.com. 6. Micrel, Inc: www.micrel.com. September 2010 35 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Figure 17. MIC2164-3 12V to 1.8V @ 10A Buck Converter September 2010 36 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Bill of Materials (MIC2164-3 12V to 1.8V @ 10A) Item Part Number C1, C8, C17, C19 06035C104KAT C2 0805ZD225MAT C3 222215095001 C4 1210YD106MAT C9 0805ZD105KAT C10 C11 C12 C15 D1 06035C222KAT 6SEPC560MX 12106D107MAT 06035C102KAT SD103BWS L1 HCF1305-1R0 Manufacturer Description Qty. (1) 0.1µF Ceramic Capacitor, X7R, Size 0603, 50V (1) 2.2µF Ceramic Capacitor, X5R, Size 0805, 10V 1 220µF Aluminum Capacitor, SMD, 35V 1 AVX AVX Vishay(2) AVX(1) 4 10µF Ceramic Capacitor, X5R, Size 1210, 16V 1 (1) 1µF Ceramic Capacitor, X5R, Size 0805, 10V 1 (1) 2.2nF Ceramic Capacitor, X7R, Size 0603, 50V 1 AVX AVX Sanyo (3) 560µF OSCON Capacitor, 6.3V 1 (1) 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V 1 (1) 1nF Ceramic Capacitor, X7R, Size 0603, 50V 1 Small Signal Schottky Diode 1 1.0µH Inductor, 20A Saturation Current 1 AVX AVX (2) Vishay (4) Cooper Bussmann (5) Q1, Q2 FDS7764A 30V N-Channel MOSFET 7.5mΩ Rds(on) @ 4.5V 2 R1 CRCW06032R21FKEY3 Vishay Dale(2) 2.21Ω Resistor, Size 0603, 1% 1 CRCW06031R21FKEY3 (2) 1.21Ω Resistor, Size 0603, 1% 1 (2) 10k Resistor, Size 0603, 1% 1 (2) 2k Resistor, Size 0603, 1% 1 (2) 8.06k Resistor, Size 0603, 1% 1 Micrel. Inc. (6) 1MHz Buck Controller 1 Micrel. Inc. (6) LDO 1 R5 R6 CRCW06031002FKEY3 R9 CRCW06032001FKEY3 R15 U1 CRCW06038061FKEY3 MIC2164-3YMM U2 MIC5233-5.0YM5 Fairchild Vishay Dale Vishay Dale Vishay Dale Vishay Dale Notes: 1. AVX: www.avx.com. 2. Vishay: www.vishay.com. 3. Sanyo: www.sanyo.com. 4. Sumida: www.sumida.com. 5. Fairchild: www.fairchildsemi.com. 6. Micrel, Inc: www.micrel.com. September 2010 37 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Recommended Land Pattern 10-Pin MSOP (MM) September 2010 38 M9999-091310-D Micrel, Inc. MIC2164/-2/-3/C Package Information 10-Pin MSOP (MM) 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. © 2009 Micrel, Incorporated. September 2010 39 M9999-091310-D