MIC23158/9 3MHz PWM Dual 2A Buck Regulator with HyperLight Load(R) and Power Good General Description Features Input voltage: 2.7V to 5.5V The MIC23158/9 is a high efficiency 3MHz dual 2A Output voltage: Adjustable (down to 1.0V) synchronous buck regulator with HyperLight Load mode, 2 independent 2A outputs Power Good output indicator, and programmable soft start. The MIC23159 also provides an auto discharge feature Up to 94% peak efficiency that switches in a 225 pull down circuit on its output to 83% typical efficiency at 1mA discharge the output capacitor when disabled. HyperLight 2 independent Power Good Indicators Load provides very high efficiency at light loads and ultra Independent programmable Soft Start fast transient response which makes the MIC23158/9 45A typical quiescent current perfectly suited for supplying processor core voltages. An 3MHz PWM operation in continuous conduction mode additional benefit of this proprietary architecture is very low Ultra fast transient response output ripple voltage throughout the entire load range with Fully integrated MOSFET switches the use of small output capacitors. The 20-pin 3mm x 4mm Output pre-bias safe (R) MLF package saves precious board space and requires 0.01A shutdown current seven external components for each channel. Thermal shutdown and current limit protection The MIC23158/9 is designed for use with a very small 20-pin 3mm x 4mm MLF package inductor, down to 0.47H, and an output capacitor as small Internal 225 pull down circuit on output (MIC23159) as 2.2 F that enables a total solution size, less than 1mm -40C to +125C junction temperature range in height. Applications The MIC23158/9 has a very low quiescent current of 45A and achieves a peak efficiency of 94% in continuous Solid State Drives (SSD) conduction mode. In discontinuous conduction mode, the Smart phones MIC23158/9 can achieve 83% efficiency at 1mA. Tablet PCs The MIC23158/9 is available in a 20-pin 3mm x 4mm MLF Mobile handsets package with an operating junction temperature range Portable devices (PMP, PND, UMPC, GPS) from -40C to +125C. WiFi/WiMax/WiBro applications Datasheets and support documentation can be found on Micrel's web site at: www.micrel.com. __________________________________________________________________________________________________________ Typical Application VIN C1 4.7F/6.3V L1 1H VOUT1 R5 10K C3 4.7F/ 6.3V R1 301K AVIN1 VIN1 AVIN2 VIN2 U1 SW1 SNS1 FB1 R2 158K SW2 SNS2 MIC23158/9 L2 1H C2 4.7F/6.3V VOUT2 R3 316K FB2 R4 221K C4 4.7F/ 6.3V R6 10K EN1 EN1 EN2 EN2 PG1 PG1 SS1 PG2 SS2 PG2 C5 470pF PGND1 PGND2 AGND1 AGND2 C6 470pF HyperLight Load is a registered trademark of Micrel, Inc. MLF and MicroLeadFrame are registered trademarks 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 June 2012 M9999-062512-A Micrel Inc. MIC23158/9 Ordering Information Nominal Output Voltage Part Number Output Auto Discharge Junction Temp. Range Package VOUT1 VOUT2 MIC23158YML ADJ ADJ NO -40C to +125C 20-Pin 3mm x 4mm MLF MIC23159YML ADJ ADJ YES -40C to +125C 20-Pin 3mm x 4mm MLF Notes: 1. Fixed output voltage options available. Contact Micrel Marketing for details. 2. MLF is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free. Pin Configuration 3mm x 4mm MLF (ML) Adjustable Output Voltage (Top View) Pin Description Pin Number (Adjustable) Pin Name Pin Function Power Input Voltage for regulator 1. Connect a capacitor to ground to decouple noise and switching transients. 1 VIN1 2 PGND1 3 SW1 Switch (Output): Internal power MOSFET output switches for regulator 1. 4 SW2 Switch (Output): Internal power MOSFET output switches for regulator 2. 5 PGND2 6 VIN2 7 AVIN2 June 2012 Power Ground for regulator 1. Power Ground for regulator 2. Power Input Voltage for regulator 2. Connect a capacitor to ground to decouple noise and switching transients. Analog Input Voltage for regulator 2. Tie to VIN2 and connect a capacitor to ground to decouple noise. 2 M9999-062512-A Micrel Inc. MIC23158/9 Analog Ground for regulator 2. Connect to a central ground point where all high current paths meet (CIN, COUT, PGND2) for best operation. 8 AGND2 9 EN2 10 SNS2 11 FB2 Feedback input for regulator 2. Connect a resistor divider from the output of regulator 2 to ground to set the output voltage. 12 PG2 Power Good output for regulator 2. Open drain output for the power good indicator for output 2. Use a pull-up resistor between this pin and VOUT2 to indicate a power good condition. 13 SS2 Soft-Start for regulator 2. Connect a minimum of 200pF capacitor to ground to set the turn-on time of regulator 2. Do not leave floating. 14 SS1 Soft-Start for regulator 1. Connect a minimum of 200pF capacitor to ground to set the turn-on time of regulator 1. Do not leave floating. 15 PG1 Power Good output for regulator 1. Open drain output for the power good indicator for output 1. Use a pull-up resistor between this pin and VOUT1 to indicate a power good condition. 16 FB1 Feedback input for regulator 1. Connect a resistor divider from the output of regulator 1 to ground to set the output voltage. 17 SNS1 18 EN1 19 AGND1 Analog Ground for regulator 1. Connect to a central ground point where all high current paths meet (CIN, COUT, PGND1) for best operation. 20 AVIN1 Analog Input Voltage for regulator 1. Tie to VIN1 and connect a capacitor to ground to decouple noise. EP ePad Exposed heat sink pad. Connect to PGND. June 2012 Enable input for regulator 2. Logic high enables operation of regulator 2. Logic low will shut down regulator 2. Do not leave floating. Sense input for regulator 2. Connect to the output of regulator 2 as close to the output capacitor as possible to accurately sense the output voltage. Sense input for regulator 1. Connect to the output of regulator 1 as close to the output capacitor as possible to accurately sense the output voltage. Enable input for regulator 1. Logic high enables operation of regulator 1. Logic low will shut down regulator 1. Do not leave floating. 3 M9999-062512-A Micrel Inc. MIC23158/9 Absolute Maximum Ratings (1) Operating Ratings Supply Voltage (AVIN1, AVIN2, VIN1, VIN2)..... -0.3V to 6V Switch1 (VSW1), Sense1 (VSNS1)...................... -0.3V to VIN1 Enable1 (VEN1), Power Good1 (VPG1) ............. -0.3V to VIN1 Feedback1 (VFB1) ........................................... -0.3V to VIN1 Switch2 (VSW2), Sense2 (VSNS2)...................... -0.3V to VIN2 Enable2 (VEN2), Power Good2 (VPG2) ............. -0.3V to VIN2 Feedback2 (VFB2) ........................................... -0.3V to VIN2 Power Dissipation TA=70C......................Internally Limited Storage Temperature Range .....................-65C to +150C Lead temperature (soldering, 10s) ............................. 260C ESD Rating(3) ..................................................ESD sensitive (2) Supply Voltage (AVIN1, VIN1) ..................... +2.7V to +5.5V Supply Voltage (AVIN2, VIN2) ..................... +2.7V to +5.5V Enable Input Voltage (VEN1, VEN2) .....................0V to VIN1,2 Output Voltage Range (VSNS1, VSNS2) .......... +1.0V to +3.3V Junction Temperature Range (TJ) .......-40C TJ +125C Thermal Resistance 3mm x 4mm MLF-20 (JA) .................................53C/W Electrical Characteristics(4) TA = 25C; AVIN1,2 = VIN1,2 = VEN1,2 = 3.6V; L1,2 = 1.0H; COUT1,2 = 4.7F unless otherwise specified. Bold values indicate -40C TJ +125C, unless noted. Parameter Condition Min. Supply Voltage Range Under Voltage Lockout Threshold Typ. 2.7 Rising 2.45 Under Voltage Lockout Hysteresis 2.55 Max. Units 5.5 V 2.65 V 75 mV Quiescent Current IOUT = 0mA , SNS > 1.2 * VOUTNOM (both outputs) 45 90 A Shutdown Current VEN = 0V; VIN = 5.5V (per output) 0.1 5 A Feedback Regulation Voltage ILOAD = 20mA 0.62 0.6355 V Feedback Bias Current (per output) 0.6045 0.01 uA Current Limit SNS = 0.9*VOUTNOM 4.3 A Output Voltage Line Regulation VIN = 3.6V to 5.5V if VOUTNOM < 2.5V, ILOAD = 20mA VIN = 4.5V to 5.5V if VOUTNOM 2.5V, ILOAD = 20mA 0.45 %/V DCM, VIN = 3.6V if VOUTNOM < 2.5V 0.55 DCM, VIN = 5.0V if VOUTNOM 2.5V 1.0 Output Voltage Load Regulation PWM Switch RDSON 2.2 CCM, VIN = 3.6V if VOUTNOM < 2.5V CCM, VIN = 5.0V if VOUTNOM 2.5V ISW1,2 = 100mA PMOS 0.20 ISW1,2 = -100mA NMOS 0.19 % 0.8 Switching Frequency IOUT = 180mA 3 Soft Start Time VOUT = 90%, CSS = 470pF 300 s Soft Start Current VSS = 0V 2.7 A Power Good Threshold (Rising) 86 Power Good Threshold Hysteresis Power Good Delay Time Rising Power Good Pull Down Resistance Enable Input Voltage 92 MHz 96 7 % 68 s 95 Logic Low 0.4 Logic High V V 1.2 Enable Input Current % 0.1 2 A 225 Over-temperature Shutdown 160 C Shutdown Hysteresis 20 C Output Discharge Resistance June 2012 MIC23159 Only; EN=0V, IOUT = 250A 4 M9999-062512-A Micrel Inc. MIC23158/9 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. June 2012 5 M9999-062512-A Micrel Inc. MIC23158/9 Typical Characteristics Efficiency (VOUT = 3.3V) vs. Output Current 100 100 90 80 80 70 VIN = 5V EFFICIENCY (%) VIN = 4.2V 60 50 40 30 20 70 VIN = 4.2V VIN = 3.6V VIN = 5V EFFICIENCY (%) 80 60 50 40 30 20 COUT=4.7F L=1H 10 10 100 1000 10000 VIN = 5V VIN = 4.2V 50 40 30 COUT=4.7F L=1H 10 100 1000 10000 1 OUTPUT CURRENT (mA) Efficiency (VOUT = 1.5V) vs. Output Current VIN = 3.6V 0 1 OUTPUT CURRENT (mA) 100 VIN = 2.7V 60 10 0 1 70 20 COUT=4.7F L=1H 10 0 Efficiency (VOUT = 1.8V) vs. Output Current 100 90 90 EFFICIENCY (%) Efficiency (VOUT = 2.5V) vs. Output Current 100 1000 10000 Current Limit vs. Input Voltage VOUT Rise Time vs. CSS 1000000 10 OUTPUT CURRENT (mA) 6.0 90 RISE TIME (s) EFFICIENCY (%) 70 VIN = 3.6V 60 VIN = 5V VIN = 2.7V VIN = 4.2V 50 40 30 20 10000 1000 100 COUT=4.7F L=1H 10 0 1 10 100 1000 CURRENT LIMIIT (A) 100000 80 VOUT = 1.8V COUT = 4.7F 10 100 10000 COUT = 4.7F 10000 100000 1000000 2.5 T = 25C 45 40 T = -40C No Switching SNS > VOUTNOM * 1.2 COUT = 4.7F 20 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) June 2012 3.0 5.0 5.5 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Line Regulation (CCM) 2.00 1.95 OUTPUT VOLTAGE (V) SHUTDOWN CURRENT (nA) QUIESCENT CURRENT (A) 50 2.5 VOUT = 1.8V 1.0 1000 T = 125C 25 2.0 Shutdown Current vs. Input Voltage 60 30 3.0 CSS (pF) Quiescent Current vs. Input Voltage 35 4.0 0.0 1000 OUTPUT CURRENT (mA) 55 5.0 100 10 1.90 IOUT = 300mA IOUT = 1A 1.85 1.80 1.75 1.70 VOUTNOM = 1.8V 1.65 1 COUT = 4.7F 1.60 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) 6 5.0 5.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) M9999-062512-A Micrel Inc. MIC23158/9 Typical Characteristics (Continued) Line Regulation (HLL) 2.00 2.00 IOUT = 80mA IOUT = 20mA 1.80 1.75 IOUT = 1mA 1.70 VOUTNOM = 1.8V 1.65 1.60 3.0 3.5 4.0 4.5 5.0 1.85 1.80 1.75 VIN = 3.6V 1.70 VOUTNOM = 1.8V 1.65 COUT = 4.7F 2.5 1.90 COUT = 4.7F 600 INPUT VOLTAGE (V) IOUT = 100mA IOUT = 400mA 3.5 3.0 IOUT = 1.2A 2.5 2.0 1.5 TA = 25C 1.0 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) June 2012 5.0 1.80 1.75 VIN = 3.6V 1.70 VOUTNOM =1.8V 1.65 COUT = 4.7F 1.60 1000 1400 20 1800 40 60 80 100 120 OUTPUT CURRENT (mA) 5.5 Switching Frequency vs. Temperature Feedback Voltage vs. Temperature 0.65 FEEDBACK VOLTAGE (V) OUTPUT VOLTAGE (V) 5.0 4.0 1.85 OUTPUT CURRENT (mA) VOUTMAX vs. VIN 4.5 1.90 0 1.60 200 5.5 1.95 5 SWITCHING FREQUENCY (MHz) 1.85 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 1.90 Load Regulation (HLL) 2.00 1.95 1.95 OUTPUT VOLTAGE (V) Load Regulation (CCM) 0.64 0.63 0.62 0.61 VIN = 3.6V 0.60 VOUT = 1.8V 0.59 -40 -20 0 20 40 60 80 TEMPERATURE (C) 7 100 120 4 3 2 VIN = 3.6V 1 VOUTNOM = 1.8V COUT = 4.7F 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C) M9999-062512-A Micrel Inc. MIC23158/9 Functional Characteristics June 2012 8 M9999-062512-A Micrel Inc. MIC23158/9 Functional Characteristics (Continued) June 2012 9 M9999-062512-A Micrel Inc. MIC23158/9 Functional Characteristics (Continued) June 2012 10 M9999-062512-A Micrel Inc. MIC23158/9 Functional Diagram VIN1 SW1 EN1 AVIN2 Control Logic: Timer & SoftStart Gate Drive ZeroX PGND1 AVIN1 Isense EN2 Control Logic: Timer & SoftStart Current Limit Current Limit VIN2 Gate Drive SW2 ZeroX Isense SNS1 PGND2 SNS2 Under-Voltage Lock Out Under-Voltage Lock Out Reference Reference Error Amplifier SS1 Error Amplifier SS2 PG1 PG2 FB1 AGND1 AGND2 FB2 Figure 1. Simplified MIC23158 Functional Block Diagram - Adjustable Output Voltage June 2012 11 M9999-062512-A Micrel Inc. MIC23158/9 VIN1 EN1 Gate Drive SW1 AVIN2 Control Logic: Timer & SoftStart ZeroX Isense PGND1 AVIN1 EN2 Control Logic: Timer & SoftStart Current Limit Current Limit VIN2 Gate Drive SW2 ZeroX Isense PGND2 SNS1 SNS2 Under-Voltage Lock Out Under-Voltage Lock Out Reference EN1 Reference Error Amplifier SS1 EN2 Error Amplifier SS2 PG1 PG2 FB1 AGND1 AGND2 FB2 Figure 2. Simplified MIC23159 Functional Block Diagram - Adjustable Output Voltage June 2012 12 M9999-062512-A Micrel Inc. MIC23158/9 current in PWM mode. The current loop for the power ground should be as small as possible and separate from the analog ground (AGND) loop as applicable. Refer to the layout recommendations for more details. Functional Description VIN The input supply (VIN) provides power to the internal MOSFETs for the switch mode regulator along with the internal control circuitry. The VIN operating range is 2.7V to 5.5V. An input capacitor with a minimum voltage rating of 6.3V is recommended. Due to the high switching speed, a minimum 2.2F bypass capacitor placed close to VIN and the power ground (PGND) pin is required. Refer to the layout recommendations for details. PG The power good (PG) pin is an open drain output which indicates when the output voltage is within regulation. This is indicated by a logic high signal when the output voltage is above the PG threshold. Connect a pull up resistor greater than 5k from PG to VOUT. SS An external soft start circuitry set by a capacitor on the SS pin reduces inrush current and prevents the output voltage from overshooting at start up. The SS pin is used to control the output voltage ramp up time and the approximate equation for the ramp time in milliseconds is 296 x 103 x ln(10) x CSS. For example, for a CSS = 470pF, TRISE 300s. Refer to the "VOUT Rise Time vs. CSS" graph in the Typical Characteristics section. The minimum recommended value for CSS is 200pF. EN A logic high signal on the enable pin activates the output voltage of the device. A logic low signal on the enable pin deactivates the output and reduces supply current to 0.1A. Do not leave the EN pin floating. When disabled, the MIC23159 switches in a 225 load from the SNS pin to AGND, to discharge the output capacitor. SW The switch (SW) connects directly to one end of the inductor and provides the current path during switching cycles. The other end of the inductor is connected to the load, SNS pin, and output capacitor. Due to the high speed switching on this pin, the switch node should be routed away from sensitive nodes whenever possible. FB The feedback (FB) pin is provided for the adjustable voltage option. This is the control input for setting the output voltage. A resistor divider network is connected to this pin from the output and is compared to the internal 0.62V reference within the regulation loop. The output voltage can be calculated using the following equation: SNS The sense (SNS) pin is connected to the output of the device to provide feedback to the control circuitry. The SNS connection should be placed close to the output capacitor. Refer to the layout recommendations for more details. The SNS pin also provides the output active discharge circuit path to pull down the output voltage when the device is disabled. R1 VOUT VREF 1 R2 Recommended feedback resistor values: AGND The analog ground (AGND) is the ground path for the biasing and control circuitry. The current loop for the signal ground should be separate from the power ground (PGND) loop. Refer to the layout recommendations for more details. VOUT R1 R2 1.2V 274k 294k 1.5V 316k 221k 1.8V 301k 158k 2.5V 324k 107k 3.3V 309k 71.5k PGND The power ground pin is the ground path for the high June 2012 13 M9999-062512-A Micrel Inc. MIC23158/9 frequency and the inductance. The lower the switching frequency or the inductance, the higher the peak current. As input voltage increases, the peak current also increases. The size of the inductor depends on the requirements of the application. Refer to the Typical Application Circuit and Bill of Materials for details. DC resistance (DCR) is also important. While DCR is inversely proportional to size, DCR can represent a significant efficiency loss. Refer to the Efficiency Considerations. The transition between Continuous Conduction Mode (CCM) to HyperLight Load mode is determined by the inductor ripple current and the load current. Application Information The MIC23158/9 is a high performance DC-DC step down regulator offering a small solution size. Supporting two outputs of up to 2A each in a 3mm x 4mm MLF package. Using the HyperLight Load switching scheme, the MIC23158/9 is able to maintain high efficiency throughout the entire load range while providing ultra fast load transient response. The following sections provide additional device application information. Input Capacitor A 2.2F ceramic capacitor or greater should be placed close to the VIN pin and PGND pin for bypassing. A Murata GRM188R60J475KE19D, size 0603, 4.7F ceramic capacitor is recommended based upon performance, size and cost. A X5R or X7R temperature rating is recommended for the input capacitor. The diagram shows the signals for High Side switch Output Capacitor The MIC23158/9 is designed for use with a 2.2F or greater ceramic output capacitor. Increasing the output capacitance will lower output ripple and improve load transient response but could also increase solution size or cost. A low equivalent series resistance (ESR) ceramic output capacitor such as the Murata GRM188R60J475KE19D, size 0603, 4.7F ceramic capacitor is recommended based upon performance, size and cost. Both the X7R or X5R temperature rating capacitors are recommended. Inductor Selection When selecting an inductor, it is important to consider the following factors: Inductance Rated current value Size requirements DC resistance (DCR) Drive (HSD) for Ton control, the Inductor current, and the Low Side switch Drive (LSD) for TOFF control. In HLL mode, the inductor is charged with a fixed Ton pulse on the high side switch. After this, the low side switch is turned on and current falls at a rate VOUT/L. The controller remains in HLL mode while the inductor falling current is detected to cross approximately -50mA. When the LSD (or TOFF) time reaches its minimum and the inductor falling current is no longer able to reach the threshold, the part is in CCM mode. Once in CCM mode, the TOFF time will not vary. Therefore, it is important to note that if L is large enough, the HLL transition level will not be triggered. That inductor is: The MIC23158/9 is designed for use with a 0.47H to 2.2H inductor. For faster transient response, a 0.47H inductor will yield the best result. For lower output ripple, a 2.2H inductor is recommended. Maximum current ratings of the inductor are generally given in two methods; permissible DC current, and saturation current. Permissible DC current can be rated either for a 40C temperature rise or a 10% to 20% loss in inductance. Ensure the inductor selected can handle the maximum operating current. When saturation current is specified, make sure that there is enough margin so that the peak current does not cause the inductor to saturate. Peak current can be calculated as follows: LMAX VOUT 135ns 2 50mA 1 VOUT /VIN IPEAK IOUT VOUT 2 f L As shown by the calculation above, the peak inductor current is inversely proportional to the switching June 2012 14 M9999-062512-A Micrel Inc. MIC23158/9 which 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: 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 IIN 100 PDCR = IOUT2 x DCR From that, the loss in efficiency due to inductor resistance can be calculated as follows: 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 current squared. During the off cycle, the low side Nchannel MOSFET conducts, also dissipating power. Device operating current also reduces efficiency. The product of the quiescent (operating) current and the supply voltage represents another DC loss. The current required driving the gates on and off at a constant 3MHz frequency and the switching transitions make up the switching losses. VOUT IOUT Efficiency Loss 1 VOUT IOUT PDCR 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. HyperLight Load Mode The MIC23158/9 uses a minimum on and off time proprietary control loop (patented by Micrel). When the output voltage falls below the regulation threshold, the error comparator begins a switching cycle that turns the PMOS on and keeps it on for the duration of the minimum-on-time. This increases the output voltage. If the output voltage is over the regulation threshold, then the error comparator turns the PMOS off for a minimumoff-time until the output drops below the threshold. The NMOS acts as an ideal rectifier that conducts when the PMOS is off. Using an NMOS switch instead of a diode allows for lower voltage drop across the switching device when it is on. The synchronous switching combination between the PMOS and the NMOS allows the control loop to work in discontinuous mode for light load operations. In discontinuous mode, the MIC23158/9 works in HyperLight Load to regulate the output. As the output current increases, the off time decreases, thus provides more energy to the output. This switching scheme improves the efficiency of MIC23158/9 during light load currents by only switching when it is needed. As the load current increases, the MIC23158/9 goes into continuous conduction mode (CCM) and switches at a frequency centered at 3MHz. The equation to calculate the load when the MIC23158/9 goes into continuous conduction mode may be approximated by the following formula: Efficiency (VOUT = 1.8V) vs. Output Current 100 90 EFFICIENCY (%) 80 70 VIN = 2.7V 60 VIN = 3.6V VIN = 5V VIN = 4.2V 50 40 30 20 COUT=4.7F L=1H 10 0 1 10 100 1000 10000 OUTPUT CURRENT (mA) Figure 3. Efficiency Under Load (V VOUT ) D ILOAD IN 2L f As shown in the previous equation, the load at which the MIC23158/9 transitions from HyperLight Load mode to PWM mode is a function of the input voltage (VIN), output voltage (VOUT), duty cycle (D), inductance (L) and frequency (f). As shown in Figure 4, as the Output Current increases, the switching frequency also increases until the MIC23158/9 goes from HyperLight Load mode to PWM mode at approximately 180mA. The MIC23158/9 will switch at a relatively constant frequency around 3MHz once the output current is over 180mA. The figure above shows an efficiency curve. From 1mA load to 2A, efficiency losses are dominated by quiescent current losses, gate drive and transition losses. By using the HyperLight Load mode, the MIC23158/9 is able to maintain high efficiency at low output currents. Over 180mA, 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, thereby reducing the internal RDSON. This improves efficiency by reducing DC losses in the device. All but the inductor losses are inherent to the device. In June 2012 100 15 M9999-062512-A Micrel Inc. MIC23158/9 Switching Frequency vs. Output Current 5.0 SWITCHING FREQUENCY (MHz) 4.5 4.0 L=1.0H 3.5 3.0 L=0.47H 2.5 2.0 1.5 1.0 0.5 0.0 0.1 1 10 100 1000 10000 OUTPUT CURRENT (mA) Figure 4. SW Frequency vs. Output Current June 2012 16 M9999-062512-A Micrel Inc. MIC23158/9 Typical Application Circuit (Adjustable Output) Bill of Materials Item C1, C2 C3, C4, C5, C6 C7, C8 L1, L2 R1 R2 R3 R4 R5, R6 R7, R8 Part Name 06036D105KAT2A GRM188R60J105KA01D C1608X5R0J105K 06036D475KAT2A GRM188R60J475KE19D C1608X5R0J475K 06035A471JAT2A GRM1885C1H471JA01D C1608C0G1H471J CDRH4D28CLDNP-1R0P LQH44PN1R0NJ0 CRCW06033013FKEA CRCW06031583FKEA CRCW06033163FKEA CRCW06032213FKEA CRCW06031003FKEA CRCW06031002FKEA Manufacturer AVX (1) Murata (2) TDK (3) AVX Murata TDK AVX Murata TDK SUMIDA (4) MURATA Vishay/Dale (5) Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale MIC23158/9YML Micrel, Inc (6) U1 Description Qty. 1F, 0603, 6.3V 2 4.7F, 6.3V, X5R, 0603 4 470pF, 50V, 0603 2 1H, 3.0A, 14m, L5.1mm x W5.1mm x H3.0mm 1H, 2.8A, 14m, L5.1mm x W5.1mm x H3.0mm 301K, 1%, 1/10W, 0603 158K, 1%, 1/10W, 0603 316K, 1%, 1/10W, 0603 221K, 1%, 1/10W, 0603 100K, 1%, 1/10W, 0603 10K, 1%, 1/10W, 0603 3MHz PWM Dual 2A Buck Regulator with Hyperlight Load and Power Good 2 1 1 1 1 2 2 1 Notes: 1. AVX: www.avx.com 2. Murata: www.murata.com June 2012 17 M9999-062512-A Micrel Inc. MIC23158/9 3. TDK: www.tdk.com 4. Sumida: www.sumida.com 5. Vishay/Dale: www.vishay.com 6. Micrel, Inc.: www.micrel.com June 2012 18 M9999-062512-A Micrel Inc. MIC23158/9 PCB Layout Recommendations Top Layer Bottom Layer June 2012 19 M9999-062512-A Micrel Inc. MIC23158/9 Package Information 20-Pin 3mm x 4mm MLF June 2012 20 M9999-062512-A Micrel Inc. MIC23158/9 Recommended Land Pattern June 2012 21 M9999-062512-A Micrel Inc. MIC23158/9 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. (c) 2012 Micrel, Incorporated. June 2012 22 M9999-062512-A