MIC4722YML-TR

MIC4722 3mm x 3mm 2.7MHz 3A PWM Buck Regulator General Description Features The Micrel MIC4722 is a high efficiency PWM buck (stepdown) regulator that provides up to 3A of output current. The MIC4722 operates at 2.7MHz that makes it suitable for next generation XDSL modems requiring operating frequencies in excess of 2.4MHz and has proprietary internal compensation that allows a closed loop bandwidth of over 200KHz. The low on-resistance internal p-channel MOSFET of the MIC4722 allows efficiencies over 92%, reduces external components count and eliminates the need for an expensive current sense resistor. The MIC4722 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 MIC4722 is available in the exposed pad 12-pin 3mm x 3mm MLF® package with a junction operating range from –40°C to +125°C. • • • • • • • • • • • • • 2.7 to 5.5V supply voltage 2.7MHz PWM mode Output current to 3A >92% efficiency 100% maximum duty cycle Adjustable output voltage option down to 1V Ultra-fast transient response Ultra-small external components Stable with a 0.47µH inductor and a 4.7µF output capacitor Fully integrated 3A 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 Applications • • • • • 5V or 3.3V Point of Load Conversion Telecom/Networking Equipment Set Top Boxes Storage Equipment Video Cards Typical Application MIC4722 3A 2.7MHz 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 2010 M9999-051410-C Micrel, Inc. MIC4722 Ordering Information Part Number Voltage MIC4722YML Junction Temp. Range Adj. Package –40° to +125°C 12-Pin 3x3 MLF Lead Finish ® Pb-Free Note: MLF® is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen 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 7 NC 12-Pin 3mm x 3mm MLF® (ML) Pin Description Pin Number Pin Name Pin Function 1,12 SW Switch (Output): Internal power P-Channel MOSFET output switch 2,11 VIN Supply Voltage (Input): Supply voltage for the source of the internal P-channel MOSFET and driver. 3,10 PGND Power Ground. Provides the ground return path for the high-side drive current. 4 SGND Signal (Analog) Ground. Provides return path for control circuitry and internal reference. 5 BIAS 6 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 EN Enable (Input). Logic level low, will shutdown the device, reducing the current draw to less than 5µA. 9 PGOOD EP GND Requires bypass capacitor to GND. May 2010 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. 2 M9999-051410-C Micrel, Inc. MIC4722 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 Junction Temperature ................................................ 150°C EDS Rating(3) .................................................................. 2kV 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 3x3 MLF-12 (θJA) ...............................................60°C/W Electrical Characteristics(4) VIN = VEN = 3.6V; L = 0.47µH; COUT = 4.7µF; TA = 25°C, unless noted. Bold values indicate –40°C< TJ < +125°C. Parameter Condition Min (turn-on) 2.45 Supply Voltage Range Under-Voltage Lockout Threshold Typ Max Units 5.5 V 2.55 2.65 V 2.7 UVLO Hysteresis 100 Quiescent Current VFB = 0.9 * VNOM (not switching) Shutdown Current VEN = 0V [Adjustable] Feedback Voltage ± 1% ILOAD = 100mA ± 2% (over temperature) ILOAD = 100mA Current Limit VFB = 0.9 * VNOM Output Voltage Line Regulation mV 570 900 µA 2 10 µA 0.99 0.98 1 1.01 1.02 V 1 nA 3.5 5 A 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 < 3A 0.2 % Maximum Duty Cycle VFB ≤ 0.4V FB pin input current Switch ON-Resistance % 100 ISW = 50mA VFB = 0.7VFB_NOM (High Side Switch) 95 200 300 mΩ Oscillator Frequency 2.4 2.7 3.0 MHz Enable Threshold 0.5 0.85 1.3 V Enable Hysteresis 50 Enable Input Current 0.1 2 µA Power Good Range ±7 ±10 % 145 250 Ω Power Good Resistance IPGOOD = 500µA mV Over-Temperature Shutdown 150 °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. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. 4. Specification for packaged product only. May 2010 3 M9999-051410-C Micrel, Inc. MIC4722 Typical Characteristics 94 4.5VIN 92 90 88 94 5VIN 92 5.5VIN 86 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 90 88 4.5VIN 5VIN 86 84 82 80 5.5VIN 78 76 74 72 70 68 66 64 62 60 0 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 3 92 90 3VIN 88 3.3VIN 86 84 82 3.6VIN 80 78 76 74 72 70 68 66 64 0 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 3 3 MIC4722 1V OUT Efficiency 80 0 90 88 86 84 82 80 78 76 74 72 70 68 66 64 62 60 0 MIC4722 2.5V OUT Efficiency 3VIN 3.3VIN 3.6VIN 84 82 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 80 0 3 86 84 82 80 78 76 74 72 70 68 66 64 0 3 MIC4722 1.2V OUT Efficiency 4.5VIN 3 MIC4722 1.5V OUT Efficiency 4.5VIN 5VIN 5.5VIN 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 3 MIC4722 1.2V OUT Efficiency 90 88 86 3VIN 84 3.3VIN 82 80 78 76 3.6VIN 74 72 70 68 66 64 62 60 0 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 5VIN 5.5VIN 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 3 MIC4722 1V OUT Efficiency 1.010 3 Load Regulation 82 80 78 5VIN 3VIN 3.3VIN 76 74 72 5.5VIN 66 64 70 68 62 66 60 0 64 0 May 2010 88 86 96 94 92 3VIN 3.3VIN 90 88 86 84 3.6VIN 82 80 78 76 74 72 70 68 66 0 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 84 4.5VIN 72 68 5.5VIN MIC4722 1.8V OUT Efficiency MIC4722 1.5V OUT Efficiency 70 92 90 82 MIC4722 1.8V OUT Efficiency 74 96 94 5VIN 84 78 76 100 98 88 82 80 78 4.5VIN 90 86 84 76 0 MIC4722 2.5V OUT Efficiency OUTPUT VOLTAGE (V) 96 MIC4722 3.3V OUT Efficiency 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 3 3.6VIN 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 4 3 1.005 1.000 0.995 0.990 0 3.3V VIN = 3.3V 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A) 3 M9999-051410-C Micrel, Inc. MIC4722 Typical Characteristics (cont.) Line Regulation 1.0010 1.010 Feedback Voltage vs. Temperature 1.0008 1.008 3.2 3.1 1.0006 1.0004 1.006 1.004 3.0 2.9 1.0002 1.002 1.000 2.8 2.7 0.998 2.6 2.5 1.0000 0.9998 Frequency vs. Temperature 0.9996 0.9994 0.996 0.994 0.9992 0.992 V = 3.3V IN 0.990 20 40 60 80 TEMPERATURE (°C) 2.4 2.3 V = 3.3V IN 2.2 20 40 60 80 TEMPERATURE (°C) Quiescent Current vs. Supply Voltage R DSON vs. Supply Voltage 0.9990 2.7 3.2 3.7 4.2 4.7 5.2 SUPPLY VOLTAGE (V) Feedback Voltage vs. Supply Voltage 1.2 800 700 1.0 110 600 0.8 0.6 0.4 105 500 100 400 95 300 90 85 200 0.2 VEN = VIN 0 012345 SUPPLY VOLTAGE (V) R DSON vs. Temperature 160 140 120 115 80 100 VEN = VIN 0 0123456 SUPPLY VOLTAGE (V) 1.2 Enable Threshold vs. Supply Voltage 75 70 2.7 1.2 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 3.2 3.7 4.2 4.7 5.2 SUPPLY VOLTAGE (V) Enable Threshold vs. Temperature 120 100 80 60 40 20 0 VIN = 3.3V May 2010 20 40 60 80 TEMPERATURE (°C) 0 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 5 0 VIN = 3.3V 20 40 60 80 TEMPERATURE (°C) M9999-051410-C Micrel, Inc. MIC4722 Functional Characteristics Discontinuous Current VIN = 3.3V VOUT = 1V L = 1µH 0A VIN = 3.3V Inductor Current (200mA/div) Inductor Current (500mA/div) Continuous Current VOUT = 1V L = 1µH COUT = 4.7µF 0A IOUT = 300mA COUT = 4.7µF Switch Voltag e (2V/div) Switch Voltag e (2V/div) IOUT = 1A Time (200ns/div ) Time (200ns/div ) Load Transient Output Voltag e AC Coupled (10mV/div) Output Current (2A/div) Output Ripple Switch Voltage (2V/div) Output Voltag e (20mV/div) 0A VIN = 3.3V VOUT = 1.8V Time (400µs/div ) IOUT = 3A Time (400ns/div ) Inductor Current (2A/div) Feedback Voltag e (1V/div) Enable Voltag e (2V/div) Input Current (1A/div) Start-Up Waveforms May 2010 Time (40µs/div ) 6 M9999-051410-C Micrel, Inc. MIC4722 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 MIC4722 Block Diagram May 2010 7 M9999-051410-C Micrel, Inc. MIC4722 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 MIC4722. 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 that the supply voltages need to be 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