Preliminary Technical Data ADP1877 Reference Design FCDC 00186 FEATURES Four Output Voltages: 1.2 V, 1.8 V, 3.3 V, 5 V Output Current: 1 A to 3.5 A Input voltage: 10.8-13.2 V Ripple 50 mV ppk Transient step ±5%, 50% max load ADP1877 REFERENCE DESIGN DESCRIPTION This ADP1877 Reference Design uses 10.8 V to 13.2 V for the input voltage. The output voltages and currents are as follows: • VOUT1 = 1.2 V with a maximum output current of 3.5 A, • VOUT2 = 1.8 V with a maximum output current of 1.4 A, • VOUT3 = 3.3 V with a maximum output current of 2.1 A, • VOUT4 = 5.0 V with a maximum output current of 2.2 A, Design criteria are for coincidental tracking of VOUT1, VOUT2 and VOUT3 with VOUT4 for both turn on and turn off. The ripple and transient assumptions are 50 mV peak to peak voltage ripple and 5% deviation due to 50% instantaneous load step. The switching frequency is fixed at 700 kHz for VOUT1 and VOUT2, 1000kHz for VOUT3 and VOUT4. 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Preliminary Technical Data FCDC 00186 TABLE OF CONTENTS Features....................................................................................................................................................................................................... 1 ADP1877 Reference Design Description .............................................................................................................................................. 1 Revision History........................................................................................................................................................................................ 2 General Description ................................................................................................................................................................................. 3 ADP1877................................................................................................................................................................................................ 3 Typical Performance Characteristics...................................................................................................................................................... 4 Schematic ................................................................................................................................................................................................. 10 TABLE OF FIGURES Figure 1. Calculated efficiency of 1.2V output ................................................................................................................................ 4 Figure 2. Calculated efficiency of 1.8V output ................................................................................................................................ 4 Figure 3. Calculated efficiency of 3.3V output ................................................................................................................................ 5 Figure 4. Calculated efficiency of 5.0V output ................................................................................................................................ 5 Figure 5. Calculated efficiency of 3.3V output with 2xSi2304BDS high and 2xSi2304BDS low.............................................. 6 Figure 6. Calculated gain and phase of 1.8V output with additional 15x10uF ceramic ............................................................ 6 Figure 7. Calculated gain and phase of 3.3V output with additional 40uF of aluminum electrolytic and 225uF of ceramic 7 Figure 8. Calculated gain and phase of 5.0V output with additional 300uF of aluminum electrolytic and 2x10uF ceramic 7 Figure 9. Calculated ripple and transient of 1.2V output with additional 10uF ceramic .......................................................... 8 Figure 10. Calculated ripple and transient of 1.8V output with additional 15x10uF ceramic ............................................... 8 Figure 11. ceramic Calculated ripple and transient of 3.3V output with additional 40uF of aluminum electrolytic and 225uF of 9 Figure 12. ceramic Calculated ripple and transient of 5.0V output with additional 300uF of aluminum electrolytic and 2x10uF 9 Figure 13. Schematic: VOUT1 and VOUT2 ......................................................................................................................................... 10 Figure 14. Schematic: VOUT3 ,VOUT4 ................................................................................................................................................ 11 REVISION HISTORY 2/12/2009—Revision 0: Initial Version Rev. 0 | Page 2 of 14 Preliminary Technical Data FCDC 00186 GENERAL DESCRIPTION ADP1877 The ADP1877 is a current mode dual-phase step-down switching controller with integrated drivers that drive Nchannel synchronous power MOSFETs. The two PWM outputs are phase shifted 180º, which reduces the input RMS current thus minimizing required input capacitance. The boost diodes are built into the ADP1877, thus lowering the overall system cost and component count. The ADP1877 can be set to operate in pulse skip high efficiency mode under light load or in forced PWM (continuous conduction mode). The ADP1877 includes programmable soft start, output overvoltage protection, programmable current limit, power good, tracking function, and programmable oscillator frequency that ranges from 200 kHz to 1.5 MHz. The ADP1877 provides an output voltage accuracy of ±1% over temperature, superior transient response and reduced output capacitance. This part can be powered from a 2.75V to 15V supply and is available in 32 pin LFCSP package. Rev. 0 | Page 3 of 14 Preliminary Technical Data FCDC 00186 TYPICAL PERFORMANCE CHARACTERISTICS Figure 1. Calculated efficiency of 1.2V output Efficiency and Loss 100% 1.200 95% 1.000 90% 0.800 80% Watt Loss Pout/Pin 85% 75% 0.600 70% 0.400 65% Vin=10.8, Eff 60% Vin=13.2, Eff 55% 0.200 Vin=10.8, Loss Vin=13.2, Loss 50% 0.001 0.501 1.001 1.501 2.001 Iout Amp Figure 2. 2.501 3.001 3.501 Calculated efficiency of 1.8V output Efficiency and Loss 100% 0.000 4.001 0.600 95% 0.500 90% 0.400 80% Watt Loss Pout/Pin 85% 75% 0.300 70% 0.200 65% Vin=10.8, Eff 60% Vin=13.2, Eff 55% 0.100 Vin=10.8, Loss Vin=13.2, Loss 50% 0.001 0.201 0.401 0.601 0.801 Iout Amp 1.001 Rev. 0 | Page 4 of 14 1.201 1.401 0.000 1.601 Preliminary Technical Data FCDC 00186 Figure 3. Calculated efficiency of 3.3V output Efficiency and Loss 100% 0.800 95% 0.700 90% 0.600 0.500 80% Watt Loss Pout/Pin 85% 75% 0.400 70% 0.300 65% Vin=10.8, Eff 60% Vin=13.2, Eff 55% Vin=10.8, Loss 0.200 0.100 Vin=13.2, Loss 50% 0.001 0.501 1.001 1.501 Iout Amp Figure 4. 2.001 Calculated efficiency of 5.0V output Efficiency and Loss 100% 0.900 95% 0.800 90% 0.700 85% 0.600 80% Watt Loss Pout/Pin 0.000 2.501 0.500 75% 0.400 70% 0.300 65% Vin=10.8, Eff 60% 0.200 Vin=13.2, Eff 55% Vin=10.8, Loss 0.100 Vin=13.2, Loss 50% 0.001 0.501 1.001 1.501 Iout Amp Rev. 0 | Page 5 of 14 2.001 0.000 2.501 Preliminary Technical Data Figure 5. FCDC 00186 Calculated efficiency of 3.3V output with 2xSi2304BDS high and 2xSi2304BDS low 94.32962k 94.39125k -61.63115 Y2 Y1 80 150 60 0 -20 Phase / degrees Gain / dB 20 53.212466 100 40 -40 50 53.205817 0 -6.64850m -50 -100 -60 -150 -80 100 200 400 1k 2k 4k 10k 20k 40k 100k 200k 400k REF A 1M freq / Hertz Figure 6. Calculated gain and phase of 1.8V output with additional 15x10uF ceramic 86.61444k 86.66495k 50.506033 Y2 Y1 80 150 60 100 Gain / dB 20 0 -20 -40 Phase / degrees 40 55.473242 50 -55.47171 1.535427m 0 -50 -100 -60 -150 -80 100 200 400 1k 2k 4k 10k 20k freq / Hertz Rev. 0 | Page 6 of 14 40k 100k 200k 400k REF A 1M Preliminary Technical Data Figure 7. FCDC 00186 Calculated gain and phase of 3.3V output with additional 40uF of aluminum electrolytic and 225uF of ceramic 52.25816k 52.25816k 0.0000000 Y2 Y1 80 150 60 100 40 Gain / dB 0 -20 Phase / degrees 66.439383 20 -40 50 -66.44201 -2.62744m 0 -50 -100 -60 -150 -80 100 200 400 1k 2k 4k 10k 20k 40k 100k 200k 400k REF A 1M freq / Hertz Figure 8. Calculated gain and phase of 5.0V output with additional 300uF of aluminum electrolytic and 2x10uF ceramic 82.27057k 82.35031k -79.73484 Y2 Y1 80 150 60 100 40 Gain / dB 20 0 -20 -40 Phase / degrees 66.670822 50 66.667860 2.962289m 0 -50 -100 -60 -150 -80 100 200 400 1k 2k 4k 10k 20k freq / Hertz Rev. 0 | Page 7 of 14 40k 100k 200k 400k REF A 1M Preliminary Technical Data Figure 9. FCDC 00186 Calculated ripple and transient of 1.2V output with additional 10uF ceramic 1.24 Vout / V 1.22 1.2 1.18 1.16 1.14 0 20 40 60 80 100 120 140 160 time/uSecs 180 20uSecs/div Figure 10. Calculated ripple and transient of 1.8V output with additional 15x10uF ceramic 1.81 Vout / V 1.805 1.8 1.795 1.79 1.785 0 20 40 60 80 100 time/uSecs 120 140 160 180 20uSecs/div Rev. 0 | Page 8 of 14 Preliminary Technical Data FCDC 00186 Figure 11. Calculated ripple and transient of 3.3V output with additional 40uF of aluminum electrolytic and 225uF of ceramic 3.315 Vout / V 3.31 3.305 3.3 3.295 3.29 0 20 40 60 80 100 120 140 160 time/uSecs 180 20uSecs/div Figure 12. Calculated ripple and transient of 5.0V output with additional 300uF of aluminum electrolytic and 2x10uF ceramic 5.08 5.06 5.04 Vout / V 5.02 5 4.98 4.96 4.94 4.92 4.9 0 20 40 60 80 100 time/uSecs 120 140 160 180 20uSecs/div Rev. 0 | Page 9 of 14 Preliminary Technical Data FCDC 00186 SCHEMATIC Figure 13. Schematic: VOUT1 and VOUT2 Rf11 Rf12 PGOOD1 Rc1 Vin = 12V Vout4 = 5V CIlim1 Rt11 Cc12 Cc11 Rr1 Css1 RIlim1 Rt12 32 31 30 29 28 27 26 25 Cbst1 CiV1 TRK1 FB1 COMP1 RAMP1 SS1 PGOOD1 ILIM1 BST1 1 Vin = 12V 2 3 Cvin RVcco 4 Cvcc 5 6 Cdr Rfreq 7 8 Vout4 = 5V EN1 SW1 U1 SYNC DH1 VIN PGND1 ADP1877 VCCO DL1 VDL DL2 AGND PGND2 FREQ DH2 EN2 SW2 QH1 24 Rgcs1 CoV1 22 QL1 21 20 19 Rgcs2 QL2 18 10 11 12 13 14 15 16 Vout2 = 1.8V L2 17 TRK2 FB2 COMP2 RAMP2 SS2 PGOOD2 ILIM2 BST2 9 Vout1 = 1.2V L1 23 CoV2 Cbst2 QH2 Rt21 Rr2 Css2 Vin = 12V Cc22 Cc21 CiV2 Rt22 CIlim2 Rc2 PGOOD2 Rf22 Rf21 Rev. 0 | Page 10 of 14 RIlim2 Preliminary Technical Data FCDC 00186 Figure 14. Schematic: VOUT3 ,VOUT4 Rf11 Rf12 PGOOD1 Rc1 Vin = 12V CIlim1 Cc12 Cc11 Rr1 Css1 RIlim1 32 Ren1 1 Vin = 12V 2 Ren2 3 Cvin 31 30 29 28 27 26 25 Cbst1 CiV1 TRK1 FB1 COMP1 RAMP1 SS1 PGOOD1 ILIM1 BST1 RVcco 4 Cvcc 5 6 Cdr Rfreq 7 8 Vout4 = 5V EN1 SW1 U1 SYNC DH1 VIN PGND1 ADP1877 VCCO DL1 VDL DL2 AGND PGND2 FREQ DH2 EN2 SW2 QH1 24 Rgcs1 CoV1 22 QL1 21 20 19 Rgcs2 QL2 18 10 11 12 13 14 15 16 Vout3 = 3.3V L2 17 TRK2 FB2 COMP2 RAMP2 SS2 PGOOD2 ILIM2 BST2 9 Vout4 = 5V L1 23 CoV2 Cbst2 QH2 Rt21 Rr2 Css2 Vin = 12V Cc22 Cc21 CiV2 Rt22 CIlim2 Rc2 PGOOD2 Rf22 Rf21 Rev. 0 | Page 11 of 14 RIlim2 Preliminary Technical Data FCDC 00186 Bill of Materials Table 1. Vout1, and Vout2 Bill of Materials (1.2 V and 1.8 V) Designator Part Number U1 ADP1877 Manufacturer Analog Devices Value Package Comment Quantity 40pin LFCSP Dual Current Mode Controller 1 QH1 NTGS3446G ON-Semi SOT23-6 Single 60mOhm 20V N-FET 1 QH2 NTGS3446G ON-Semi SOT23-6 Single 60mOhm 20V N-FET 1 QL1 NTGS3446G ON-Semi SOT23-6 Single 60mOhm 20V N-FET 2 QL2 NTGS3446G ON-Semi Single 60mOhm 20V N-FET 1 L1 DO1813H-122 Coilcraft 1.15uH SOT23-6 Unshielded Drum Core Ferrite 1 L2 LPS5030-822 Coilcraft 8.2uH Shielded Drum Core Ferrite 1 CoV1 JMK212BJ226MG-T Taiyo Yuden 22uF 0805 MLCC / X5R / 6.3V 2 CoV2 JMK212BJ106MG-T Taiyo Yuden 10uF 0805 MLCC / X5R / 6.3V 1 CiV1 EMK212BJ106KG-T Taiyo Yuden 10uF 0805 MLCC / X5R / 16V 1 CiV2 EMK212BJ106KG-T Taiyo Yuden 10uF 0805 MLCC / X5R / 16V 1 Cvin Cbst1, Cbst2 GRM21BR71C105K Murata 1uF 0805 MLCC / X7R / 16V 1 Generic 10% Vishay 100nF 0805 Boost Capacitor / COG or X7R 2 Css1 Generic 10% Vishay 10nF 0805 Soft Start Capacitor / COG or X7R 1 Css2 Generic 10% Vishay 10nF 0805 Soft Start Capacitor / COG or X7R 1 CIlim1 Generic 10% Vishay 33pF 0805 Current Limit Capacitor 1 CIlim2 Generic 10% Vishay 33pF 0805 Current Limit Capacitor 1 Cdr GRM185R60J105KE21 Murata 1uF 0603 MLCC / X5R / 6.3V 1 Cvcc GRM185R60J105KE21 Murata 1uF 0603 MLCC / X5R / 6.3V 1 Cc11 Generic 10% Vishay 470pF 0603 Compensation Capacitor - CH1 1 Cc12 Generic 10% Vishay 5pF 0603 Compensation Capacitor - CH1 1 Cc21 Generic 10% Vishay 68pF 0603 Compensation Capacitor - CH2 1 Cc22 Generic 10% Vishay 5pF 0603 Compensation Capacitor - CH2 1 RIlim1 Generic 1% Vishay 2.4k 0603 Current Limit Resistor 1 RIlim2 Generic 1% Vishay 2.2k 0603 Current Limit Resistor 1 Rgcs1 Generic 1% Vishay 22k 0603 Current Sense Gain Set - 6V/V 1 Rgcs2 No Pop Vishay 0603 Current Sense Gain Set - 12V/V 1 Rfreq Generic 5% Vishay 82k 0603 Frequency Set Resistor - 700kHz 1 Rvcco Generic 10% Vishay 1 Ohms 0603 Decoupling Resistor 1 Rr1 Generic 10% Vishay 240k 0603 Vout 1 Ramp Resistor 1 Rr2 Generic 10% Vishay 430k 0603 Vout 2 Ramp Resistor 1 Rc1 Generic 10% Vishay 20k 0603 Compensation Resistor 1 Rc2 Generic 10% Vishay 240k 0603 Compensation Resistor 1 Rf11 Generic 1% Vishay 10k 0603 Feedback Resistor - CH1 1 Rf12 Generic 1% Vishay 10k 0603 Feedback Resistor - CH1 1 Rf21 Generic 1% Vishay 20k 0603 Feedback Resistor - CH2 1 Rf22 Generic 1% Vishay 10k 0603 Feedback Resistor - CH2 1 Rt11 Generic 1% Vishay 10k 0603 Voltage track Resistor - CH1 1 Rt12 Generic 1% Vishay 10k 0603 Voltage track Resistor - CH1 1 Rt21 Generic 1% Vishay 20k 0603 Voltage track Resistor - CH2 1 Rt22 Generic 1% Vishay 10k 0603 Voltage track Resistor - CH2 1 Rev. 0 | Page 12 of 14 Preliminary Technical Data FCDC 00186 Vout3 and Vout4 Bill of Materials (3.3 V and 5.0 V) Designator Part Number U1 ADP1877 Manufacturer Analog Devices QH1 NTGS3446G QH2 NTGS3446G QL1 NTGS3446G Value Package Comment Quantity 40pin LFCSP Dual Current Mode Controller 1 ON-Semi SOT23-6 Single 60mOhm 20V N-FET 1 ON-Semi SOT23-6 Single 60mOhm 20V N-FET 1 ON-Semi SOT23-6 Single 60mOhm 20V N-FET 1 QL2 NTGS3446G ON-Semi Single 60mOhm 20V N-FET 1 L1 MSS1048-682 Coilcraft 6.8uH Shielded Drum Core SOT23-6 Ferrite 1 Ferrite 1 MLCC / X5R / 6.3V 1 L2 MSS1048-682 Coilcraft 6.8uH Shielded Drum Core CoV1 JMK212BJ106MG-T Taiyo Yuden 10uF 0805 CoV2 JMK212BJ106MG-T Taiyo Yuden 10uF 0805 MLCC / X5R / 6.3V 1 CiV1 EMK212BJ106KG-T Taiyo Yuden 10uF 0805 MLCC / X5R / 16V 1 CiV2 EMK212BJ106KG-T Taiyo Yuden 10uF 0805 MLCC / X5R / 16V 1 Cvin Cbst1, Cbst2 GRM21BR71C105K Murata 1uF 0805 MLCC / X7R / 16V 1 Generic 10% Vishay 100nF 0805 Boost Capacitor / COG or X7R 2 Css1 Generic 10% Vishay 100nF 0805 Soft Start Capacitor / COG or X7R 1 Css2 Generic 10% Vishay 10nF 0805 Soft Start Capacitor / COG or X7R 1 CIlim1 Generic 10% Vishay 33pF 0805 Current Limit Capacitor 1 CIlim2 Generic 10% Vishay 33pF 0805 Current Limit Capacitor 1 Cdr GRM185R60J105KE21 Murata 1uF 0603 MLCC / X5R / 6.3V 1 Cvcc GRM185R60J105KE21 Murata 1uF 0603 MLCC / X5R / 6.3V 1 Cc11 Generic 10% Vishay 33pF 0603 Compensation Capacitor - CH1 1 Cc12 Generic 10% Vishay 5pF 0603 Compensation Capacitor - CH1 1 Cc21 Generic 10% Vishay 68pF 0603 Compensation Capacitor - CH2 1 Cc22 Generic 10% Vishay 5pF 0603 Compensation Capacitor - CH2 1 RIlim1 Generic 1% Vishay 3.3k 0603 Current Limit Resistor 1 RIlim2 Generic 1% Vishay 3.0k 0603 Current Limit Resistor 1 Rgcs1 Generic 1% Vishay 22k 0603 Current Sense Gain Set - 6V/V 1 Rgcs2 Generic 1% Vishay 22k 0603 Current Sense Gain Set - 6V/V 1 Rfreq Generic 5% Vishay 51k 0603 Frequency Set Resistor - 700kHz 1 Rvcco Generic 10% Vishay 1 Ohms 0603 Decoupling Resistor 1 Rr1 Generic 10% Vishay 750k 0603 Vout 1 Ramp Resistor 1 Rr2 Generic 10% Vishay 750k 0603 Vout 2 Ramp Resistor 1 Rc1 Generic 10% Vishay 51k 0603 Compensation Resistor 1 Rc2 Generic 10% Vishay 240k 0603 Compensation Resistor 1 Rf11 Generic 1% Vishay 11k 0603 Feedback Resistor - CH1 1 Rf12 Generic 1% Vishay 1.5k 0603 Feedback Resistor - CH1 1 Rf21 Generic 1% Vishay 10k 0603 Feedback Resistor - CH2 1 Rf22 Generic 1% Vishay 2.2k 0603 Feedback Resistor - CH2 1 Rt11 Generic 1% Vishay 10k 0603 Voltage track Resistor - CH1 1 1 Rt12 Generic 1% Vishay 10k 0603 Voltage track Resistor - CH1 Ren1 Generic 1% Vishay 150k 0603 Voltage track Resistor - CH2 1 Ren2 Generic 1% Vishay 10k 0603 Voltage track Resistor - CH2 1 Rev. 0 | Page 13 of 14 Preliminary Technical Data FCDC 00186 NOTES Reference designators shown on the schematic but not listed on the Bill of Materials are place holders for possible design adjustments (snubbers, additional decoupling capacitors and clamp diodes). These components should be put in the layout, but not populated unless after testing it is deemed necessary. If a different number, or different type of output capacitors are used on the switching outputs the loop compensation components may need adjustment. The assumed additional output caps are listed on the transient and bode plot figures. Efficiency calculations are estimates and are not verified in actual hardware. FETs and other components with quantities greater than 1 are connected in parallel with the other FETs / components of the same reference designator. Paralleled FETs should be placed physically close together and have large power planes connecting all the drains together and large power planes connecting all the sources together. Gate drive resistors may be used if there is concern about possible paralleling issues. Ground symbols with multiple parallel lines (not the triangle symbol) designator should be connected together with one small plane and tied to the power ground plane (triangle symbol) at one point near the IC. Each IC should have its own signal ground pour. The PGND1 and PGND2 pins should be connected directly to the source of the lowside MOSFET for that channel with short wide traces. They should not connect into the main ground plane except at the MOSFET sources. ©2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. EB Rev. 0 | Page 14 of 14