MIC4720YMME

MIC4720 3mm x 3mm 2.0MHz 2A Integrated Switch Buck Regulator General Description Features The Micrel MIC4720 is a high efficiency PWM buck (stepdown) regulator that provides up to 2A of output current. The MIC4720 operates at 2.0MHz and has proprietary internal compensation that allows a closed loop bandwidth of over 200KHz. • • • • • • • • The low on-resistance internal p-channel MOSFET of the MIC4720 allows efficiencies over 92%, reduces external components count and eliminates the need for an expensive current sense resistor. The MIC4720 operates from 2.7V to 5.5V input and the output can be adjusted down to 1V. The devices can operate with a maximum duty cycle of 100% for use in lowdropout conditions. The MIC4720 is available in the exposed pad 12-pin 3mm x 3mm MLF® and 10-pin ePad MSOP package with a junction operating range from –40°C to +125°C. • • • • • • 2.7 to 5.5V supply voltage 2.0MHz PWM mode Output current to 2A Up to 94% efficiency 100% maximum duty cycle Adjustable output voltage option down to 1V Ultra-fast transient response Ultra-small external components Stable with a 1µH inductor and a 4.7µF output capacitor Fully integrated 2A MOSFET switch Micropower shutdown Thermal shutdown and current limit protection Pb-free 12-pin 3mm x 3mm MLF® package –40°C to +125°C junction temperature range Pb-free 10-pin ePad MSOP package Applications • • • • • • • • • FPGA/DSP/ASIC applications General point of load Broadband communications DVD/TV recorder Point of Sale Printers/Scanners Set Top Boxes Computing Peripherals Video Cards Typical Application MIC4720 3.3V OUT Efficiency 100 VIN = 4.5V MIC4720 EFFICIENCY (%) 95 90 V = 5.0V IN 85 V = 5.5V IN 80 75 2 1.8 1.6 1.4 1 1.2 0.8 0.6 0.4 0 65 0.2 70 OUTPUT CURRENT (A) 2A 2.0MHz Buck Regulator 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 May 2007 M9999-051707 Micrel, Inc. MIC4720 Ordering Information Part Number Voltage Junction Temp. Range Package MIC4720YML Adj. –40° to +125°C 12-Pin 3x3 MLF MIC4720YMME Adj. –40° to +125°C 10-Pin ePad MSOP Lead Finish ® Pb-Free Pb-Free Pin Configuration SW 1 12 SW VIN 2 11 VIN PGND 3 10 PGND SGND 4 9 PGOOD BIAS 5 FB 6 8 EN EP 1 10 SW VIN 2 9 VIN SGND 3 8 PGND BIAS 4 7 PGOOD FB 5 6 EN 7 NC 10-Pin ePad MSOP (MM) 12-Pin 3mm x 3mm MLF® (ML) May 2007 SW 2 M9999-051707 Micrel, Inc. MIC4720 Pin Description Pin Number ® MLF Pin Number MSOP Pin Name 1,12 1, 10 SW Switch (Output): Internal power P-Channel MOSFET output switch 2,11 2, 9 VIN Supply Voltage (Input): Supply voltage for the source of the internal P-channel MOSFET and driver. Pin Function Requires bypass capacitor to GND. 3,10 8 PGND Power Ground. Provides the ground return path for the high-side drive current. 4 3 SGND Signal (Analog) Ground. Provides return path for control circuitry and internal reference. 5 4 BIAS 6 5 FB Feedback. Input to the error amplifier, connect to the external resistor divider network to set the output voltage. 7 — NC No Connect. Not internally connected to die. This pin can be tied to any other pin if desired. 8 6 EN Enable (Input). Logic level low, will shutdown the device, reducing the current draw to less than 5µA. 9 7 PGOOD EP — GND May 2007 Internal circuit bias supply. Must be bypassed with a 0.1µF ceramic capacitor to SGND. Power Good. Open drain output that is pulled to ground when the output voltage is within +/- 7.5% of the set regulation voltage Connect to ground. 3 M9999-051707 Micrel, Inc. MIC4720 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) .......................................................+6V Output Switch Voltage (VSW). .........................................+6V Output Switch Current (SW).............................................11A Logic Input Voltage (VEN) .................................. –0.3V to VIN Storage Temperature (Ts) .........................–60°C to +150°C Supply voltage (VIN) ..................................... +2.7V to +5.5V Logic Input Voltage (VEN) ....................................... 0V to VIN Junction Temperature (TJ) ........................ –40°C to +125°C Junction Thermal Resistance 3mm×3mm MLF-12 (θJA) ...................................60°C/W 3mm×3mm MLF-12 (θJC)...................................10°C/W 10 pin ePad MSOP (θJA)....................................76°C/W 10 pin ePad MSOP (θJC)....................................28°C/W Electrical Characteristics(3) VIN = VEN = 3.6V; L = 1µH; COUT = 4.7µF; TA = 25°C, unless noted. Bold values indicate –40°C< TJ < +125°C. Parameter Condition Min (turn-on) 2.45 UVLO Hysteresis Quiescent Current Max 5.5 V 2.55 2.65 V 2.7 Supply Voltage Range Under-Voltage Lockout Threshold Typ 100 VFB = 0.9 × VNOM (not switching) Shutdown Current VEN = 0V [Adjustable] Feedback Voltage ± 2% (over temperature) ILOAD = 100mA 570 2 0.98 FB pin input current mV 900 µA 10 µA 1.02 V 1 nA 5 A Current Limit VFB = 0.9 × VNOM Output Voltage Line Regulation VOUT > 2V; VIN = VOUT+500mV to 5.5V; ILOAD= 100mA VOUT < 2V; VIN = 2.7V to 5.5V; ILOAD= 100mA 0.07 % Output Voltage Load Regulation 20mA < ILOAD < 2A 0.2 % Maximum Duty Cycle VFB ≤ 0.4V Switch ON-Resistance 3.5 Units 100 ISW = 200mA VFB = GND (High Side Switch) % 95 200 300 mΩ Oscillator Frequency 1.8 2.0 2.2 MHz Enable Threshold 0.5 0.85 1.3 V Enable Hysteresis 50 Enable Input Current 0.1 Power Good Range Power Good Resistance IPGOOD = 500µA mV 2.3 µA ±7 ±10 % 150 250 Ω Over-Temperature Shutdown 160 °C Over-Temperature Hysteresis 25 °C Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Specification for packaged product only. May 2007 4 M9999-051707 Micrel, Inc. MIC4720 1.8V 90 MIC4720 Efficiency OUT 95 EFFICIENCY (%) V = 5.0V V = 5.5V IN IN 75 70 85 80 OUTPUT CURRENT (A) 1.8 2 1.6 1.4 0.8 1 1.8 2 1.6 1.4 1.2 0.8 1 1.8 2 1.4 1.6 EFFICIENCY (%) IN V = 3.6V IN 65 60 1.8 2 1.6 1.4 1.2 0.8 1 0.6 0.4 0.2 50 0 1.8 2 1.6 1.4 1.2 66 OUTPUT CURRENT (A) 1.0010 Line Regulation 1.0008 1.0006 1.0004 1.0002 0.9996 0.9994 64 1.8 2 0.9992 1.6 62 60 V = 3.3V 1.0000 0.9998 68 1.4 1.8 2 1.6 1.4 1.2 0.8 1 0.6 0.4 0 0.2 69 IN 70 1.2 71 V = 5.5V IN 0.8 1 73 V = 5.0V 0.6 IN 74 72 0.4 75 IN 0.2 V =3.6V V = 4.5V 76 EFFICIENCY (%) IN IN 70 MIC4720 Efficiency OUT 78 0 V =3.3V 0.8 1 0 1.2V IN V = 3.0V 55 MIC4720 Efficiency V =3.0V MIC4720 1VOUT Efficiency 75 OUTPUT CURRENT (A) OUT 81 1.2 40 OUTPUT CURRENT (A) 83 0.8 1 45 35 30 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0 0.2 70 50 0.6 75 85 69 80 VIN = 5.5V 55 0.4 80 65 60 0.2 V = 5.5V IN 1.2V 0.6 0 EFFICIENCY (%) IN 71 85 IN VIN = 5.0V IN OUTPUT CURRENT (A) V = 4.5V 70 V = 5.5V 73 67 65 MIC4720 1VOUT Efficiency 75 IN 85 0.4 70 IN 0.6 75 V = 5.0V 75 0.4 IN 80 V = 4.5V V = 5.0V EFFICIENCY (%) V = 3.6V 79 77 0 IN OUTPUT CURRENT (A) MIC4720 3.3V OUT Efficiency 95 IN 81 V = 3.3V 0.2 EFFICIENCY (%) 80 65 1.8 2 1.6 1.4 1.2 0.8 1 0.6 0.4 0 0.2 EFFICIENCY (%) V = 3.6V V = 4.5V 83 IN 85 0.2 90 75 100 EFFICIENCY (%) 0.6 MIC4720 1.5V OUT Efficiency OUTPUT CURRENT (A) EFFICIENCY (%) 0.4 2 1.8 1.6 1.4 1 65 MIC4720 1.5V OUT Efficiency 80 May 2007 75 MIC4720 2.5V OUT Efficiency IN 67 65 IN 80 OUTPUT CURRENT (A) IN 79 77 V = 5.5V OUTPUT CURRENT (A) 85 65 IN OUTPUT CURRENT (A) V = 3.3V 90 V = 5.0V 70 0.8 65 85 0 80 0.6 2 1.8 1.6 1.4 1 1.2 0.8 IN 0.4 V = 3.6V 0.2 EFFICIENCY (%) IN 0 V = 3.3V 0.6 90 85 0.2 IN 0.4 IN IN V = 3.0V 70 V = 4.5V V = 4.5V V = 3.0V 95 90 MIC4720 2.5V OUT Efficiency 1.2 MIC4720 Efficiency OUT 1.2 1.8V 0.2 93 91 89 87 85 83 81 79 77 75 73 71 69 67 65 0 EFFICIENCY (%) Typical Characteristics OUTPUT CURRENT (A) 5 0.9990 2.7 3.2 3.7 4.2 4.7 5.2 SUPPLY VOLTAGE (V) M9999-051707 Micrel, Inc. MIC4720 Typical Characteristics (cont.) 1.010 Feedback Voltage vs. Temperature 1.008 2.5 2.4 1.006 1.004 2.3 2.2 1.002 1.000 2.1 2.0 0.998 1.9 1.8 0.996 0.994 Quiescent Current vs. Supply Voltage 500 400 300 200 0 0 1.2 RDSON vs. Supply Voltage VEN = VIN 1 2 3 4 5 SUPPLY VOLTAGE (V) Enable Threshold vs. Supply Voltage 6 0 0 160 80 75 20 0.6 0.6 0.4 0.4 0.2 0.2 0 R DSON vs. Temperature 80 40 70 2.7 0.8 1 2 3 4 5 SUPPLY VOLTAGE (V) 120 60 1.2 VEN = VIN 140 90 85 0.8 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 0.2 100 1.0 May 2007 0.4 100 95 1.0 0 2.7 0.6 110 105 600 100 0.8 120 115 700 1.2 Feedback Voltage vs. Supply Voltage 1.0 1.7 1.6 V = 3.3V IN 1.5 20 40 60 80 TEMPERATURE (°C) 0.992 V = 3.3V IN 0.990 20 40 60 80 TEMPERATURE (°C) 800 Frequency vs. Temperature 3.2 3.7 4.2 4.7 5.2 SUPPLY VOLTAGE (V) 0 VIN = 3.3V 20 40 60 80 TEMPERATURE (°C) Enable Threshold vs. Temperature VIN = 3.3V 20 40 60 80 TEMPERATURE (°C) 6 M9999-051707 Micrel, Inc. MIC4720 Functional Characteristics Load Transient Output Voltage (20mV/div) Inductor Current (500mA/div) Continuous Current VIN = 3.3V VOUT = 1V L = 1µH COUT = 4.7µF Output Current (1A/div) Switch Voltage (2V/div) IOUT = 1.3A Time (200ns/div) VIN = 3.3V VOUT = 1.0V Time (100µs/div) Output Current (2A/div) Output Voltage AC Coupled (10mV/div) Switch Voltage (2V/div) Output Ripple May 2007 VIN = 3.3V VOUT = 1.0V IOUT = 2A Time (200ns/div) 7 M9999-051707 Micrel, Inc. MIC4720 Functional Diagram VIN VIN P-Channel Current Limit BIAS HSD SW SW PWM Control EN Enable and Control Logic Bias, UVLO, Thermal Shutdown Soft Start EA FB 1.0V PGOOD 1.0V PGND SGND MIC4720 Block Diagram May 2007 8 M9999-051707 Micrel, Inc. MIC4720 Pin Description SW The switch (SW) pin connects directly to the inductor and provides the switching current necessary to operate in PWM mode. Due to the high speed switching on this pin, the switch node should be routed away from sensitive nodes. This pin also connects to the cathode of the free-wheeling diode. VIN Two pins for VIN provide power to the source of the internal P-channel MOSFET along with the current limiting sensing. The VIN operating voltage range is from 2.7V to 5.5V. Due to the high switching speeds, a 10µF capacitor is recommended close to VIN and the power ground (PGND) for each pin for bypassing. Please refer to layout recommendations. PGOOD Power good is an open drain pull down that indicates when the output voltage has reached regulation. For a power good low, the output voltage is within ±10% of the set regulation voltage. For output voltages greater or less than 10%, the PGOOD pin is high. This should be connected to the input supply through a pull up resistor. A delay can be added by placing a capacitor from PGOOD to ground. BIAS The bias (BIAS) provides power to the internal reference and control sections of the MIC4720. A 10Ω resistor from VIN to BIAS and a 0.1µF from BIAS to SGND is required for clean operation. EN The enable pin provides a logic level control of the output. In the off state, supply current of the device is greatly reduced (typically 100MHz bandwidth is more than sufficient for most power supplies (which includes both linear and switching) and are more common and significantly cheaper than the injection transformers previously mentioned. The one disadvantage to using the op-amp injection method; is the supply voltages need to below the maximum operating voltage of the op-amp. Also, the maximum output voltage for driving 50Ω inputs using the MIC922 is 3V. For measuring higher output voltages, 1MΩ input impedance is required for the A and R channels. Remember to always measure the output voltage with an oscilloscope to ensure the measurement is working properly. You should see a single sweeping sinusoidal waveform without distortion on the output. If there is distortion of the sinusoid, reduce the amplitude of the source signal. You could be overdriving the feedback causing a large signal response. Figure 7. Transformer Injection A 50Ω resistor allows impedance matching from the network analyzer source. This method allows the DC loop to maintain regulation and allow the network analyzer to insert an AC signal on top of the DC voltage. The network analyzer will then sweep the source while monitoring A and R for an A/R measurement. While this is the most common method for measuring the gain and phase of a power supply, it does have significant limitations. First, to measure low frequency gain and phase, the transformer needs to be high in inductance. This makes frequencies