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MIC38300
3A SuperLNRTM 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 SuperLNRTM 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 x 6mm x 0.9mm MLF(R) 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 4x6x0.9mm (R) MLF package and can operate from -40C to +125C. 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
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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
3.0A
Voltage(1)
ADJ
Junction Temperature Range
-40C to +125C
Package
PB-Free 28-Pin 4x6 MLF
(R)
Note: For additional voltage options, contact Micrel.
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MIC38300
Pin Configuration
SWO 1 SWO 2 SWO 3 SWO 4 SWO 5 SW ePAD AVIN LPF
6 7 8 9 28 SW 27 SW 26 SW 25 SW 24 SW 23 SW 22 ePAD 21 PGND 20 PGND 19 PGND 18 EN 12 13 14 15 16 17
AGND 10 FB
11
LDOOUT
LDOOUT
PVIN
LDOIN
28-Pin 4mm x 6mm MLF(R) (ML) (Top View)
Pin Description
Pin Number MIC38300HYHL
1, 2, 3, 4, 5 6, 23, 24, 25, 26, 27, 28 7, 22 8 9 10 11 12, 13 14, 15 16, 17 18
Pin Name
SWO SW ePAD AVIN LPF AGND FB LDOOUT LDOIN PVIN EN
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. Exposed heat-sink pad. Recommend to connect to PGND. Analog Supply Voltage: Supply for the analog control circuitry. Requires bypass capacitor to ground. Low Pass Filter: Floating for typical applications. Attach external resistor from SW 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 10F. 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 50A. 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.
19, 20, 21
PGND
Note: Prefix H indicates VOUT >1V, prefix L indicates VOUT is between 0.7V to 1V.
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LDOIN
PVIN
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Micrel, Inc.
MIC38300
Absolute Maximum Ratings(1)
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)...................-65C TJ +150C ESD Rating(4) ................................................................. 2kV
Operating Ratings(2)
Supply voltage (VIN) ...................................... 3.0V to 5.5V Junction Temperature Range ........ -40C TJ +125C Enable Input Voltage (VEN) ................................. 0V to VIN Package Thermal Resistance 4mm x 6mm MLF-28 (JA) .............................40C/W
Electrical Characteristics(5)
TA = 25C with VIN = VEN = 5V; VEN = VIN; IOUT = 10mA, VOUT = 1.8V. Bold values indicate -40C TJ +125C, unless noted.
Parameter Supply Voltage Range Under-Voltage Lockout Threshold UVLO Hysteresis LDO Quiescent Current Turn-on Time Shutdown Current Feedback Voltage Feedback Current VIN - VO; Dropout Voltage Current Limit Output Voltage Load Regulation Output Voltage Line Regulation Output Ripple Over-Temperature Shutdown Over-Temperature Shutdown Hysteresis Enable Input Enable Input Threshold Enable Hysteresis Enable Input Current
Notes: 1. 2. 3. 4. 5.
Conditions Turn-on IOUT = 0A, VOUT to 5% of regulation, I ILOAD = 3A VEN = 0V 1% 2.5% ILOAD = 3.0A VFB = 0.9xVNOM VOUT = 1.8V, 10mA to 3A VOUT = 1.8V, VIN from 3.0V to 5.5V ILOAD = 2A, COUTLDO = 20F, COUTSW = 20F LPF=25k
Min 3.0
Typ 2.75 100 1 200 35
Max 5.5
Units V V mV mA
350 50 1.01 1.025 1 1.2
s A V V A V A % %/V mV C C
0.99 0.975
1 1
4.5
6 0.3 0.35 5 150 20 1 0.5
Regulator enable
0.90 20
1 120 0.01
1.1 200
V mV A
Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = (TJ(max) - TA) / JA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. Specification for packaged product only.
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MIC38300
Typical Characteristics
MIC38300 PSRR
90 80 70 60 50 40 30 20 10 0 10 100 1k 10k FREQUENCY (Hz) 100k 1.820 1.815 1.810 1.805 1.800 1.795 1.790 1.785 1.780 0 VIN = 3.3V VOUT = 1.8V COUT = 10F 0.5 1.0 1.5 2.0 2.5 LOAD CURRENT (A) 3.0
Load Regulation
2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6
Output Voltage vs. Input Voltage
10mA 2A
0.4 VOUT = 1.8V 0.2 COUT = 10F 0 0 1 2 3 4 INPUT VOLTAGE (V)
5
1.88 1.86 1.84 1.82 1.80 1.78 1.76 1.74 1.72
Output Voltage vs. Temperature
Thermal Shutdown
2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 V = 3.3V 0.4 IN VOUT = 1.8V 0.2 COUT = 10F 0 -40 10 60 110 160 TEMPERATURE (C)
90 80 70 60 50 40 30 20 10 0 0
MIC38300 Efficiency
VIN = 3.3V COUT = 10F IOUT = 10mA 20 40 60 80 TEMPERATURE (C)
VIN = 5V VOUT = 3.3V COUT = 10F 0.5 1.0 1.5 2.0 2.5 LOAD CURRENT (A) 3.0
210
Enable Threshold
1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 3.0 VOUT = 1.8V COUT = 10F 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 3.0
Current Limit vs. Input Voltage
VOUT = 1.8V COUT = 10F 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5
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MIC38300
Functional Characteristics
VIN = 3.3V, VOUT = 1.8V, COUT = 10F, Inductor = 470nH
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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). 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 10F 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 1F capacitor as close to AVIN as possible is recommended. Output Capacitor The MIC38300 requires an output capacitor for stable operation. As a Cap LDO, the MIC38300 can operate with ceramic output capacitors of 10F or greater. Values of greater than 10F 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 100F electrolytic in parallel with a 10F ceramic can provide the transient and high frequency noise performance of a 100F 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, 20F capacitors are recommended at LDOIN and LDOOUT. 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. Adjustable Regulator Design
OUT *CFF 0.1F ADJ 1.0V *Required only for large values of R1 and R2 R2 R1
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 100k because of the very high input impedance and low bias current of the sense amplifier. For large value resistors (>50K) R1 should be bypassed by a small capacitor (CFF = 0.1F bypass capacitor) to avoid instability due to phase lag at the ADJ/SNS input. The output resistor divider values are calculated by:
R1 VOUT = 1 V + 1 R2
Efficiency Considerations Efficiency is defined as the amount of useful output power, divided by the amount of power supplied.
V xI Efficiency _ % = OUT OUT V xI IN IN x 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
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Micrel, Inc. 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 x DCR From that, the loss in efficiency due to inductor resistance can be calculated as follows;
MIC38300
VOUT x IOUT x 100 Efficiency _ Loss = 1 - V OUT x 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.
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MIC38300
Package Information
28-Pin 4mm x 6mm MLF (ML)
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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. (c) 2007 Micrel, Incorporated.
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