MIC38300 3A SuperLNR™ Low Noise High Efficiency Regulator ADVANCED INFORMATION General Description Features The MIC38300 is a 3A peak, 2.2A continuous output • 3A peak output current current step down converter and the first device in a new • 2.2A continuous operating current generation of SuperLNR™ providing the benefits of LDOs • Input voltage range: 3.0V to 5.5V in respect to ease of use, fast transient performance, high • Adjustable output voltage down to 1.0V PSRR and low noise while offering the efficiency of a • Output noise less than 5mV switching regulator. • Ultra fast transient performance As output voltages move lower, the output noise and transient response of a switching regulator become an • Unique switcher plus LDO architecture increasing challenge for designers. By combining a • Fully integrated MOSFET switches switcher whose output is slaved to the input of a high • Micro-power shutdown performance LDO, high efficiency is achieved with a clean • Easy upgrade from LDO as power dissipation low noise output. The MIC38300 is designed to provide becomes an issue less than 5mV of peak to peak noise and over 70dB of PSRR at 1kHz. Furthermore, the architecture of the • Thermal shutdown and current limit protection MIC38300 is optimized for fast load transients allowing to • 4mm × 6mm × 0.9mm MLF® package maintain less than 30mV of output voltage deviation even during ultra fast load steps, making the MIC38300 an ideal Applications choice for low voltage ASICs and other digital ICs. The MIC38300 features a fully integrated switching • Point-of-load applications regulator and LDO combo, operates with input voltages • Networking, server, industrial power from 3.0V to 5.5V input and offers adjustable output • Wireless base-stations voltages down to 1.0V. • Sensitive RF applications The MIC38300 is offered in the small 28-pin 4×6×0.9mm ® MLF package and can operate from –40°C to +125°C. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com ___________________________________________________________________________________________________________ Typical Application MIC38300 PSRR 90 80 70 60 50 40 30 20 10 0 10 100 1k 10k FREQUENCY (Hz) 100k SuperLNR is a trademark of Micrel, Inc. MLF and MicroLeadFrame are registered trademark of Amkor Technologies Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com July 2007 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Block Diagram PVIN Switch Control AVIN SW SWO PGND LPF LDOIN VREF Voltage Reference VEN LDOOUT FB EN AGND MIC38300 Ordering Information Part Number MIC38300HYHL Output Current Voltage(1) Junction Temperature Range 3.0A ADJ –40°C to +125°C Package PB-Free 28-Pin 4x6 MLF ® Note: For additional voltage options, contact Micrel. July 2007 2 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Pin Configuration SWO 1 28 SW SWO 2 27 SW SWO 3 26 SW SWO 4 25 SW SWO 5 24 SW SW 6 23 SW ePAD 7 22 ePAD AVIN 8 21 PGND LPF 9 20 PGND AGND 10 19 PGND 18 EN LDOIN 15 16 17 PVIN 14 PVIN 13 LDOIN 12 LDOOUT 11 LDOOUT FB 28-Pin 4mm x 6mm MLF® (ML) (Top View) Pin Description Pin Number MIC38300HYHL Pin Name 1, 2, 3, 4, 5 SWO 6, 23, 24, 25, 26, 27, 28 SW 7, 22 ePAD Exposed heat-sink pad. Recommend to connect to PGND. 8 AVIN Analog Supply Voltage: Supply for the analog control circuitry. Requires bypass capacitor to ground. 9 LPF Low Pass Filter: Floating for typical applications. Attach external resistor from SW to increase hysteretic frequency. 10 AGND 11 FB 12, 13 LDOOUT 14, 15 LDOIN 16, 17 PVIN 18 EN 19, 20, 21 PGND Pin Name Switch (Output): This is the output of the PFM Switcher. Switch Node: Floating for typical applications. Attach external resistor from LPF to increase hysteretic frequency. Analog Ground. Feedback: Input to the error amplifier. Connect to the external resistor divider network to set the output voltage. LDO Output (Output): Output of voltage regulator. Place capacitor to ground to bypass the output voltage. Nominal bypass capacitor is 10µF. LDO Input: Connect to SW output. Requires a bypass capacitor to ground. Input Supply Voltage (Input): Requires bypass capacitor to GND. Enable (Input): Logic low will shut down the device, reducing the quiescent current to less than 50µA. This pin can also be used as an under-voltage lockout function by connecting a resistor divider from EN/UVLO pin to VIN and GND. Power Ground. Note: Prefix H indicates VOUT >1V, prefix L indicates VOUT is between 0.7V to 1V. July 2007 3 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) .........................................................6V Output Switch Voltage (VSW) ...........................................6V Output Switch Current (ISW) .............................................8A LDO Output Voltage (VOUT) .............................................6V Logic Input Voltage (VEN, VLQ)..........................VIN to –0.3V Power Dissipation .................................. Internally Limited(3) Storage Temperature (TS)...................–65°C ≤ TJ ≤ +150°C ESD Rating(4) ................................................................. 2kV Supply voltage (VIN) ...................................... 3.0V to 5.5V Junction Temperature Range ........ –40°C ≤ TJ ≤ +125°C Enable Input Voltage (VEN) ................................. 0V to VIN Package Thermal Resistance 4mm × 6mm MLF-28 (θJA) .............................40°C/W Electrical Characteristics(5) TA = 25°C with VIN = VEN = 5V; VEN = VIN; IOUT = 10mA, VOUT = 1.8V. Bold values indicate –40°C ≤ TJ ≤ +125°C, unless noted. Parameter Conditions Min Supply Voltage Range Under-Voltage Lockout Threshold Typ 3.0 Turn-on UVLO Hysteresis Max Units 5.5 V 2.75 V 100 mV 1 mA LDO Quiescent Current IOUT = 0A, Turn-on Time VOUT to 5% of regulation, I ILOAD = 3A 200 350 µs Shutdown Current VEN = 0V 35 50 µA Feedback Voltage ±1% ±2.5% 1 1 1.01 1.025 V V 1 µA 1.2 V 0.99 0.975 Feedback Current VIN – VO; Dropout Voltage ILOAD = 3.0A Current Limit VFB = 0.9×VNOM Output Voltage Load Regulation VOUT = 1.8V, 10mA to 3A 0.3 1 % Output Voltage Line Regulation VOUT = 1.8V, VIN from 3.0V to 5.5V 0.35 0.5 %/V Output Ripple ILOAD = 2A, COUTLDO = 20µF, COUTSW = 20µF LPF=25kΩ 4.5 6 A 5 mV Over-Temperature Shutdown 150 °C Over-Temperature Shutdown Hysteresis 20 °C Enable Input Enable Input Threshold Regulator enable Enable Hysteresis 0.90 1 1.1 V 20 120 200 mV Enable Input Current 0.01 µA Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = (TJ(max) – TA) / θJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. 4. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. 5. Specification for packaged product only. July 2007 4 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Typical Characteristics MIC38300 PSRR Load Regulation 90 1.820 80 1.815 70 1.810 60 1.805 50 1.800 40 1.795 30 20 1.790 10 1.785 0 10 1.88 100 1k 10k FREQUENCY (Hz) 100k Output Voltage vs. Temperature 1.84 1.82 1.80 1.78 1.74 1.72 1.780 0 VIN = 3.3V COUT = 10µF IOUT = 10mA 20 40 60 80 TEMPERATURE (°C) 70 5.5 1.10 5.0 1.05 4.5 1.00 4.0 0.95 3.5 0.90 5 80 1.2 1.0 0.8 0.6 V = 3.3V 0.4 IN VOUT = 1.8V 0.2 COUT = 10µF 0 -40 10 60 110 160 TEMPERATURE (°C) 1.15 2A MIC38300 Efficiency 1.6 1.4 6.0 July 2007 3.0 90 1.20 0.80 3.0 0.5 1.0 1.5 2.0 2.5 LOAD CURRENT (A) 10mA 0.4 VOUT = 1.8V 0.2 COUT = 10µF 0 0 1 2 3 4 INPUT VOLTAGE (V) 2.0 1.8 Enable Threshold 0.85 VIN = 3.3V VOUT = 1.8V COUT = 10µF 1.6 1.4 1.2 1.0 0.8 0.6 Thermal Shutdown 1.86 1.76 2.0 1.8 Output Voltage vs. Input Voltage 60 50 40 30 20 10 210 0 0 VIN = 5V VOUT = 3.3V COUT = 10µF 0.5 1.0 1.5 2.0 2.5 LOAD CURRENT (A) 3.0 Current Limit vs. Input Voltage 3.0 VOUT = 1.8V COUT = 10µF 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) VOUT = 1.8V COUT = 10µF 2.5 5.5 2.0 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5 5.5 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Functional Characteristics VIN = 3.3V, VOUT = 1.8V, COUT = 10µF, Inductor = 470nH July 2007 6 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Application Information Enable Input The MIC38300 features a TTL/CMOS compatible positive logic enable input for on/off control of the device. High enables the regulator while low disables the regulator. In shutdown the regulator consumes very little current (only a few microamperes of leakage). For simple applications the enable (EN) can be connected to VIN (IN). Adjustable Regulator Design OUT *CFF 0.1µF ADJ 1.0V *Required only for large values of R1 and R2 Input Capacitor VIN provides power to the MOSFETs for the switch mode regulator section, along with the current limiting sensing. Due to the high switching speeds, a 10µF capacitor is recommended close to VIN and the power ground (PGND) pin for bypassing. Analog VIN (AVIN) provides power to the analog supply circuitry. AVIN and VIN must be tied together. Careful layout should be considered to ensure high frequency switching noise caused by VIN is reduced before reaching AVIN. A 1µF capacitor as close to AVIN as possible is recommended. R2 Adjustable Regulator with Resistors The adjustable MIC38300 output voltage can be programmed from 1V to 5.0V using a resistor divider from output to the SNS pin. Resistors can be quite large, up to 100kΩ because of the very high input impedance and low bias current of the sense amplifier. For large value resistors (>50KΩ) R1 should be bypassed by a small capacitor (CFF = 0.1µF bypass capacitor) to avoid instability due to phase lag at the ADJ/SNS input. The output resistor divider values are calculated by: ⎛ R1 ⎞ VOUT = 1V ⎜ + 1⎟ R 2 ⎝ ⎠ Output Capacitor The MIC38300 requires an output capacitor for stable operation. As a µCap LDO, the MIC38300 can operate with ceramic output capacitors of 10µF or greater. Values of greater than 10µF improve transient response and noise reduction at high frequency. X7R/X5R dielectric-type ceramic capacitors are recommended because of their superior temperature performance. X7R-type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic capacitors. Larger output capacitances can be achieved by placing tantalum or aluminum electrolytics in parallel with the ceramic capacitor. For example, a 100µF electrolytic in parallel with a 10µF ceramic can provide the transient and high frequency noise performance of a 100µF ceramic at a significantly lower cost. Specific undershoot/overshoot performance will depend on both the values and ESR/ESL of the capacitors. For less than 5mV noise performance at higher current loads, 20µF capacitors are recommended at LDOIN and LDOOUT. Efficiency Considerations Efficiency is defined as the amount of useful output power, divided by the amount of power supplied. ⎛V ×I Efficiency _ % = ⎜⎜ OUT OUT ⎝ VIN × I IN ⎞ ⎟⎟ × 100 ⎠ Maintaining high efficiency serves two purposes. It reduces power dissipation in the power supply, reducing the need for heat sinks and thermal design considerations and it reduces consumption of current for battery powered applications. Reduced current draw from a battery increases the devices operating time and is critical in hand held devices. There are two types of losses in switching converters; DC losses and switching losses. DC losses are simply the power dissipation of I2R. Power is dissipated in the high side switch during the on cycle. Power loss is equal to the high side MOSFET RDSON multiplied by the Switch Current2. During the off cycle, the low side N-channel MOSFET conducts, also dissipating power. Device operating current also reduces efficiency. The product of the quiescent (operating) current and the supply voltage is another DC loss. Over 100mA, efficiency loss is dominated by MOSFET RDSON and inductor losses. Higher input supply voltages will increase the Gate to Source threshold on the internal MOSFETs, reducing the internal RDDSON. This improves efficiency by reducing DC losses in the device. All but the inductor losses are inherent to the device. In which Low Pass Filter Pin The MIC38300 features a Low Pass Filter (LPF) pin for adjusting the switcher frequency. By tuning the frequency, the user can further improve output ripple without losing efficiency. July 2007 R1 7 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 case, inductor selection becomes increasingly critical in efficiency calculations. As the inductors are reduced in size, the DC resistance (DCR) can become quite significant. The DCR losses can be calculated as follows: L_PD = IOUT2 × DCR From that, the loss in efficiency due to inductor resistance can be calculated as follows; July 2007 ⎡ ⎛ ⎞⎤ VOUT × IOUT ⎟⎥ × 100 Efficiency _ Loss = ⎢1 − ⎜⎜ ⎟ ⎣⎢ ⎝ VOUT × IOUT + L _ PD ⎠⎦⎥ Efficiency loss due to DCR is minimal at light loads and gains significance as the load is increased. Inductor selection becomes a trade-off between efficiency and size in this case. 8 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Package Information 28-Pin 4mm x 6mm MLF (ML) July 2007 9 M9999-070607 (408) 944-0800 Micrel, Inc. MIC38300 Recommended Landing Pattern LP # HMLF46T-28LD-LP-1 All units are in mm Tolerance ± 0.05 if not noted Red circle indicates Thermal Via. Size should be .300-.350 mm in diameter and it should be connected to GND plane for maximum thermal performance. 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 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. © 2007 Micrel, Incorporated. July 2007 10 M9999-070607 (408) 944-0800