RT9911 6 Channel DC/DC Converters General Description Features The RT9911 is a complete power-supply solution for digital still cameras and other hand-held devices. It integrates one selectable Boost/Buck DC/DC converter, one high efficiency step-down DC/DC converter, one high efficiency main step-up converter, one PWM converter for CCD positive voltage, one inverter for CCD negative voltage and one white LED driver for LCD backlight. The RT9911 is z 1.6V to 5.5V Battery Input Voltage Range z Synchronous Boost/Buck Selectable DC/DC Converter ` Internal Switches ` Up to 95% Efficiency Syn-Buck DC/DC Converters ` 0.8V to 5.5V Adjustable Output Voltage ` Up to 95% Efficiency ` 100%(MAX) Duty Cycle ` Internal Switches Main Boost DC/DC Converter ` Adjustable Output Voltage ` Up to 97% Efficiency PWM Converter for CCD Positive Voltage Inverter for CCD Negative Voltage White LED Driver for LCD Panel Backlight Up to 1.4MHz Adjustable Switching Frequency 1μ μA Supply Current in Shutdown Mode External Compensation Network for all Converters Independent Enable Pin to Shutdown Each Channel. 40-Lead VQFN Package RoHS Compliant and 100% Lead (Pb)-Free z targeted for applications that use either two or three primary cells or a single lithium-ion battery. RT9911 is available in VQFN-40L 6x6. Each DC-DC converter has independent shutdown input. Ordering Information RT9911 z z z Package Type QV : VQFN-40L 6x6 (V-Type) Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) Note : z z z z z Richtek products are : ` ` RoHS compliant and compatible with the current require- z ments of IPC/JEDEC J-STD-020. z Suitable for use in SnPb or Pb-free soldering processes. Pin Configurations z PVDD2 COMP2 FB2 SELECT EN1 EN2 EN3 EN5 z Digital Still Camera PDA Protable Device EN6 z EN4 (TOP VIEW) Applications 40 39 38 37 36 35 34 33 32 31 GND OK2 RT VREF VDDM GND FB1 COMP1 PGND1 LX1 1 30 2 29 3 28 4 27 5 26 GND 6 25 7 24 8 23 41 9 22 21 10 LX2 PGND2 FB3 COMP3 CS3 DRN3 DRP3 VFB6 CFB6 COMP6 PVDD3 EXT6 EXT4 FB4 COMP4 PVDD5 EXT5 FB5 PVDD1 COMP5 11 12 13 14 15 16 17 18 19 20 VQFN-40L 6x6 DS9911-05 April 2011 www.richtek.com 1 RT9911 Typical Application Circuit VBAT VS 3.3V VBAT 1.8V to 3.2V I/O 3.3V 500mA D9 11 C3 to C6 10µFx4 R2 470k Q1 C7 100pF PVDD1 10 LX1 7 FB1 9 PGND1 R3 150k C8 0.1µF R1 510k 34 SELECT VS 3.3V L1 4.7µH C19 1µF EXT4 RT9911 PVDD5 EXT5 2 OK2 1 GND R4 300k C10 100pF 33 R5 240k 31 C11 10µF VBAT GND SS0520 3 R10 C15 to Q2 C18 10µFx4 EXT6 VBAT 25 DRN3 Q3 24 DRP3 28 FB3 COMP1 8 VFB6 CFB6 EN1 EN1 EN3 EN4 EN5 EN6 R8 2.2M R9 205k C29 10µF R11 1M CCD -8V/40mA C26 to C27 10µFx2 R12 125k C28 4.7µF R22 20k L6 4.7µH SS0520 D8 19 Q6 CS3 R7 90.9k C25 100pF 13 6 C22 100pF L5 3.3µH Q5 PVDD3 COMP6 R6 100pF 470k PVDD2 L3 4.7µH 26 C14 14 VREF 4 COMP5 C12 to C13 10µFx2 D5 C21 10µF CCD 12V 20mA VBAT C23 C24 1µF 10µF Bottom PAD 20 Motor 5V 500mA FB2 COMP4 VS 3.3V FB5 COMP3 C9 10µF 15 Q4 D7 30 LX2 COMP2 VCORE 1.8V 300mA RT D6 18 FB4 17 3.3V 29 PGND2 L2 4.7µH L4 4.7µH SS0520 5 VDDM C1 to C2 10µFx2 C20 10µF 23 22 35 36 37 38 39 40 C30 4.7µF R13 300k D1 D2 D3 D4 EN1 EN2 EN3 EN4 EN5 EN6 R14 10 32 27 16 12 21 R15 to R21 1M C31 to C36 Figure 1. Application Circuit for 2-Cells Battery Supply Note : z Bottom pad is GND pad, can be short to pin 6 (GND). z Please remove Q2 when use Async Boost and remove D5 when use Sync Boost. www.richtek.com 2 DS9911-05 April 2011 RT9911 VBAT 3.4V to 4.2V C22 1µF C1 to C2 10µFx2 R1 470k R2 150k C10 to C11 10µFx2 L2 4.7uH R4 470k Q2 VDDM SELECT Bottom PAD PVDD3 GND EXT6 L5 3.3µH Q5 SS0520 3 R12 C27 100pF 13 VBAT 25 DRN3 Q3 24 DRP3 28 FB3 COMP1 R9 90.9k 8 VFB6 CFB6 EN1 EN1 EN3 EN4 EN5 EN6 6 D8 19 23 22 35 36 37 38 39 40 C30 10µF R13 1M C28 10µF R14 125k C29 4.7µF CCD -8V 40mA R24 20k L6 4.7µH SS0520 Q6 CS3 COMP5 C18 to C21 10µFx4 L3 4.7µH 26 14 VREF 4 9 PGND1 PGND2 29 COMP4 R8 470k D5 R10 2.2M C26 10µF 15 FB2 COMP3 C15 to C16 10µFx2 C25 100pF R11 205k D7 2 OK2 1 GND VBAT 10pF RT FB5 20 C17 EXT5 COMP2 Motor 5V 500mA PVDD2 C12 100pF R5 226k Q1 DDR 2.5V 250mA FB1 30 LX2 33 R3 510k C24 10µF Q4 RT9911 PVDD5 31 2.5V 18 CCD 12V 20mA VBAT VBAT C8 to C9 10µFx2 D6 FB4 17 C7 100pF 7 C13 0.1µF EXT4 COMP6 C3 to C6 10µFx4 L4 4.7µH SS0520 5 34 11 PVDD1 L1 4.7µH 10 LX1 I/O 3.3V 500mA C23 10µF VBAT VBAT C31 4.7µF R15 300k D1 D2 D3 D4 EN1 EN2 EN3 EN4 EN5 EN6 R16 10 32 27 16 12 21 R17 to R23 1M C32 to C37 Figure 2. Application Circuit for Li-ion Battery Supply Note : z Bottom pad is GND pad, can be short to pin 6 (GND). z Please remove Q2 when use Async Boost and remove D5 when use Sync Boost. z Output voltage setting CH1: 0.8Vx(1+R1/R2) ex: I/O 3.3V = 0.8x(1+470k/150k) CH2: 0.8Vx(1+R4/R5) ex: DDR 2.5V = 0.8x(1+470k/226k) CH3: 0.8Vx(1+R8/R9) ex: MOTOR 5V = 0.8x(1+470k/90.9k) CH4: 1.0Vx(1+R10/R11) ex: CCD 12V = 1.0x(1+2.2M/205k) CH5: -1.0Vx(R13/R14) ex: CCD -8V = -1.0x(1M/125k) DS9911-05 April 2011 www.richtek.com 3 RT9911 Functional Pin Description Pin No. Pin Name Pin Function I/O Internal State at Shut Down I/O Configuration OK 2 1 GND Analog Ground Pin -- -- 2 OK2 External Switch Control. OUT High Impedance 3 RT OUT Pull Low 5 VDDM Device Input Power Pin IN -- 6 GND Analog Ground Pin -- -- Frequency Setting Pin. Frequency is 500kHz if RT pin not connected. GND VDDM + - RT GND VDDM 1.0V 4 VREF 1.0V Reference Pin OUT High Impedance + - VREF 7 FB1 8 COMP1 9 PGND1 10 Feedback Input Pin of CH1. Feedback Compensation Pin of IN High Impedance OUT Pull Low Power Ground Pin of CH1. -- -- LX1 Switch Node of CH1. OUT High Impedance 11 PVDD1 Power Input Pin of CH1. IN -- 12 COMP5 OUT Pull Low CH1. Feedback Compensation Pin of CH5. 0.8V FB1 + COMP1 - PVDD1 LX1 PGND1 FB5 + COMP5 - 13 FB5 Feedback Input Pin of CH5. IN High Impedance 14 EXT5 External Power Switch of CH5. OUT Pull High PVDD5 15 PVDD5 16 COMP4 17 FB4 Power Input Pin of CH4, CH5 and CH6. Feedback Compensation Pin of CH4. Feedback Input Pin of CH4. EXT5 IN -- OUT Pull Low IN 1.0V FB4 + COMP4 - High Impedance To be continued www.richtek.com 4 DS9911-05 April 2011 RT9911 Pin No. Pin Name Pin Function I/O Internal State at I/O Configuration Shut Down PVDD5 18 EXT4 External Power Switch of CH4. OUT Pull Low EXT4 PVDD5 19 EXT6 External Power Switch of CH6. OUT Pull Low 20 PVDD3 Power Input Pin of CH3. IN -- 24 DRP3 External PMOS Switch Pin for CH3. OUT 21 COMP6 22 CFB6 Feedback Compensation Pin of CH6. Current Feedback Input Pin for CH6. EXT6 PVDD3 DRP3 Pull High OUT Pull Low IN High Impedance 0.2V CFB6 + - COMP6 VFB6 1.0V 23 VFB6 Voltage Feedback Input Pin for CH6. IN High Impedance + - 50uA PVDD3 25 DRN3 External NMOS Switch Pin for CH3. OUT Pull Low DRN3 VDDM 26 CS3 Current Sense Input Pin for CH3 IN High Impedance CS3 To be continued DS9911-05 April 2011 www.richtek.com 5 RT9911 Pin No. Pin Name 27 COMP3 28 FB3 29 Pin Function Feedback Compensation Pin of I/O Internal State at Shut Down OUT Pull Low Feedback Input Pin of CH3. IN High Impedance PGND2 Power Ground Pin of CH2 -- -- 30 LX2 Switch Node of CH2 OUT High Impedance 31 PVDD2 Power Input Pin of CH2. IN -- 32 COMP2 OUT Pull Low 33 FB2 IN High Impedance CH3 Feedback Compensation Pin of CH2. Feedback Input Pin of CH2. I/O Configuration 0.8V FB3 COMP3 + - PVDD2 LX2 PGND2 0.8V FB2 + - COMP2 VDDM CH1 Boost/Buck Selection Pin. 34 SELECT Logic state can’t be changed during IN Pull Low SELECT operation. 2uA VDDM 35 EN1 Enable Input Pin of CH1. IN Pull Low EN1 2uA VDDM 36 EN2 Enable Input Pin of CH2. IN Pull Low EN2 2uA To be continued www.richtek.com 6 DS9911-05 April 2011 RT9911 Pin No. Pin Name Pin Function I/O Internal State at Shut Down I/O Configuration VDDM 37 EN3 Enable Input Pin of CH3. IN EN3 Pull Low 2uA VDDM 38 EN4 Enable Input Pin of CH4. IN EN4 Pull Low 2uA VDDM 39 EN5 Enable Input Pin of CH5. IN EN5 Pull Low 2uA VDDM 40 EN6 Enable Input Pin of CH6. IN EN6 Pull Low 2uA The exposed pad must be soldered Exposed Pad (41) GND to a large PCB and connected to GND for maximum power -- -- -- dissipation. DS9911-05 April 2011 www.richtek.com 7 RT9911 Function Block Diagram VDDM EN4 PVDD5 EXT4 COMP4 FB4 CH4 V-Mode Step-Up PWM - SELECT EN1 PVDD1 CH1 C-Mode Step-Up or Step-Down LX1 + PGND1 COMP1 1.0V REF EN5 - PVDD5 + 0.8V REF CH5 Inverter EXT5 COMP5 FB5 FB1 EN2 PVDD2 + CH2 C-Mode Step-Down 1.0V REF VREF LX2 PGND2 COMP2 FB2 OK2 Switch Controller + 0.8V REF EN6 EN3 PVDD3 PVDD5 CH6 WLED EXT6 VFB6 - DRP3 CH3 C-Mode Step-Up PVDD3 + DRN3 1.0V REF 50uA CS3 COMP6 - CFB6 + Oscillator Thermal Shutdown RT GND + 0.2V REF www.richtek.com 8 COMP3 FB3 0.8V REF DS9911-05 April 2011 RT9911 Absolute Maximum Ratings z z z z z z z z z (Note 1) Supply Voltage, VDDM ----------------------------------------------------------------------------------------- −0.3V to 7V Power Switch ---------------------------------------------------------------------------------------------------- −0.3V to (VDD + 0.3V) The Other Pins -------------------------------------------------------------------------------------------------- −0.3V to 7V Power Dissipation, PD @ TA = 25°C VQFN−40L 6x6 -------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) VQFN-40L 6x6, θJA --------------------------------------------------------------------------------------------Junction Temperature -----------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Mode) ----------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------- Recommended Operating Conditions z z z z 2.778W 36°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Dimming Control Frequency Range, CH6 ---------------------------------------------------------------- 300Hz to 900Hz Supply Voltage, VDDM ----------------------------------------------------------------------------------------- 2.4V to 5.5V Junction Temperature Range --------------------------------------------------------------------------------- −40°C to 125°C Operation Temperature Range ------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VDDM = 3.3V, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit -- -- 1.6 V 2.4 5.9 -6.5 5.5 -- V V EN1 = EN2 = EN3 = EN4 = EN5 = EN6 = 0V -- 1 10 μA VDDM = 3.3V, Non-Switching -- -- 430 μA VDDM = 3.3V, Non-Switching -- -- 350 μA I Q3 VDDM = 3.3V, Non-Switching -- -- 350 μA I Q4 VDDM = 3.3V, Non-Switching -- -- 300 μA I Q5 VDDM = 3.3V, Non-Switching -- -- 300 μA I Q6 VDDM = 3.3V, Non-Switching -- -- 350 μA Supply Voltage VDDM Minimum Startup Voltage VST (Note 5) VDDM Operating Voltage VDDM Over Voltage Protection VDDM VDDM Pin Voltage Supply Current Shutdown Supply Current into VDDM I OFF CH1 (Sync-Boost or Syn-Buck) I Q1 Supply Current into VDDM CH2 (Sync-Buck) Supply Current into I Q2 VDDM CH3 (Sync-Boost) Supply Current into VDDM CH4 (Asyn-Boost) Supply Current into VDDM CH5 (Asyn-Inverter) Supply Current into VDDM CH6 (Asyn-Boost) Supply Current into VDDM To be continued DS9911-05 April 2011 www.richtek.com 9 RT9911 Parameter Symbol Test Conditions Min Typ Max Unit Oscillator Operation Frequency CH1 Maximum Duty Cycle (Boost) f OSC DMAX1 RT Open SELECT = 3.3V, VFB1 = 0.7V 450 80 550 85 650 90 kHz % CH1 Maximum Duty Cycle (Buck) CH2 Maximum Duty Cycle DMAX1 DMAX2 SELECT = 0V, VFB1 = 0.7V VFB2 = 0.7V 100 100 --- --- % % CH3 Maximum Duty Cycle DMAX3 VFB3 = 0.7V 75 80 90 % CH4 Maximum Duty Cycle CH5 Maximum Duty Cycle DMAX4 DMAX5 VFB4 = 0.9V VFB5 = 0.1V 90 94 98 % CH6 Maximum Duty Cycle DMAX6 VCFB6 = 0.18V, VFB6 = 0.9V 0.788 0.8 0.812 V 0.98 1 1.02 V −15 -- -1 +15 -- mV V 0.18 0.2 0.22 V 0.984 1 1.016 V -- -- 10 mV -- 0.2 -- ms -- 22 -- μA -- 22 -- μA RDS(ON)P1 P-MOSFET, PVDD1 = 3.3V -- 200 300 mΩ RDS(ON)N1 N-MOSFET, PVDD1 = 3.3V -- 200 300 mΩ 1.3 2 4 A SELECT=1 RDS(ON)P2 P-MOSFET, PVDD2 = 3.3V 2 -- 2.5 300 4 450 A mΩ RDS(ON)N2 N-MOSFET, PVDD2 = 3.3V -- 300 450 mΩ 1.3 2 4 A RDS(ON)NP3 P-MOSFET, PVDD3 = 3.3V -- 6 15 Ω RDS(ON)NN3 N-MOSFET, PVDD3 = 3.3V -- 6 15 Ω RDS(ON)PP3 P-MOSFET, PVDD3 = 3.3V -- 6 15 Ω RDS(ON)PN3 N-MOSFET, PVDD3 = 3.3V -- 6 15 Ω RDS(ON)P4 P-MOSFET, PVDD3 = 3.3V -- 6 15 Ω RDS(ON)N4 N-MOSFET, PVDD3 = 3.3V -- 6 15 Ω Feedback Regulation Voltage Feedback Regulation Voltage @ FB1, FB2, FB3 VFB1, 2,3 Feedback Regulation Voltage @FB4 VFB4 Feedback Regulation Voltage @ FB5 VFB5 Feedback Regulation Voltage @ VFB6 VVFB6 Feedback Regulation Voltage @ CFB6 VCFB6 Reference VREF Output Voltage VREF Load Regulation VREF 0μA < I REF < 100μA Error Amplifier GM (CH1, CH2, CH3, CH4, CH5, CH6) Compensation Source Current (CH1, CH2, CH3, CH4, CH5, CH6) Compensation Sink Current (CH1, CH2, CH3, CH4, CH5, CH6) Power Switch CH1 On Resistance of MOSFET CH1 Switch Current Limitation (Buck) CH1 Switch Current Limitation (Boost) CH2 On Resistance of MOSFET SELECT=0 CH2 Switch Current Limitation CH3 On Resistance of DRN3 CH3 On Resistance of DRP3 CH4 On Resistance of MOSFET To be continued www.richtek.com 10 DS9911-05 April 2011 RT9911 Parameter Symbol Test Conditions Min Typ Max Unit RDS(ON)P5 P-MOSFET, PVDD5 = 3.3V -- 6 15 Ω RDS(ON)N5 N-MOSFET, PVDD5 = 3.3V -- 6 15 Ω RDS(ON)P6 P-MOSFET, PVDD5 = 3.3V -- 6 15 Ω RDS(ON)N6 N-MOSFET, PVDD5 = 3.3V -- 6 15 Ω 90 -- -- μA 5 40 10 50 15 60 μA μA SELECT = 0V 0.3 0.4 0.5 V SELECT = 0V -- 1 -- V VDDM = 3.3V -- -- 1.3 V VDDM = 3.3V 0.4 -- -- V VDDM = 3.3V -- 2 6 μA Select Pin Input High Level Threshold -- -- 1.3 V Select Pin Input Low Level Threshold 0.4 -- -- V -- 2 6 μA 125 180 -- °C -- 20 -- °C Power Switch CH5 On Resistance of MOSFET CH6 On Resistance of MOSFET Switch Controller OK2 pin Sink Current OK2 = 1V External Current Setting (CH3) CS3 Sourcing Current VFB6 Sink Current ICS3 IVFB6 Protection Under Voltage Protection Threshold Voltage @ FB1, FB2 Over Voltage Protection @ FB1, FB2 Control EN1, EN2, EN3, EN4, EN5, EN6 Input High Level Threshold EN1, EN2, EN3, EN4, EN5, EN6 Input Low Level Threshold EN1, EN2, EN3, EN4, EN5, EN6 Sink Current Select Pin Sink Current ISELECT Thermal Protection Thermal Shutdown TSD Thermal Shutdown Hysteresis ΔTSD Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. θJA is measured in the natural convection at T A = 25°C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Note 3. Devices are ESD sensitive. Handling precaution recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. A Schottky retifier connected from LX1 to PVDD1 is required for low-voltage startup, refer to Figure 1. DS9911-05 April 2011 www.richtek.com 11 RT9911 Typical Operating Characteristics CH1 Buck Efficiency vs. Output Current 100 90 90 80 80 70 70 Efficiency (%) Efficiency (%) CH1 Boost Efficiency vs. Output Current 100 VIN = 3.2V = 2.5V = 2.0V = 1.5V 60 50 40 30 20 10 0 60 VIN = 3.0V = 3.4V = 3.8V = 4.5V 50 40 30 20 Ch1 Boost VOUT = 3.3V 10 0 10 100 1000 Ch1 Buck VOUT = 2.5V 10 100 Output Current (mA) Output Current (mA) CH1 Boost LX1 and Output Voltage Ripple CH1 Buck LX1 and Output Voltage Ripple VIN = 1.8V, VOUT = 3.3V, IOUT = 100mA 1000 VOUT (10mV/Div) VOUT (10mV/Div) LX1 (2V/Div) LX1 (2V/Div) VIN = 4.2V, VOUT = 3.3V, IOUT = 100mA CH1 Boost Load Transient Response CH1 Buck Load Transient Response VIN = 3.0V, VOUT = 3.3V VIN = 4.2V, VOUT = 3.3V IOUT (200mA/Div) IOUT (100mA/Div) VOUT (100mV/Div) Time (1μs/Div) VOUT (100mV/Div) Time (1μs/Div) Time (1ms/Div) www.richtek.com 12 Time (1ms/Div) DS9911-05 April 2011 RT9911 CH1 Buck Output Voltage vs. Output Current 3.375 3.29 3.374 3.28 3.373 Output Voltages (V) Output Voltage (V) CH1 Boost Output Voltage vs. VDDM Voltage 3.30 3.27 3.26 3.25 3.24 3.23 3.22 3.21 3.372 3.371 3.370 3.369 3.368 3.367 3.366 VIN = 2.5V, VOUT = 3.3V, IOUT = 250mA VIN = 3.7V, VOUT = 3.3V 3.365 3.20 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 0 5.6 100 200 VDDM Voltage (V) 400 500 600 700 800 900 Loading Current (mA) CH2 Buck Efficiency vs. Output Current CH1 Boost Output Voltage vs. Output Current 3.330 100 3.329 90 3.328 80 3.327 70 Efficiency (%) Output Voltages (V) 300 3.326 3.325 3.324 3.323 3.322 VIN = 2.5V = 3.0V = 3.8V = 4.5V 60 50 40 30 20 3.321 10 VIN = 2.4V, VOUT = 3.3V 3.320 VOUT = 1.8V 0 100 200 300 400 500 600 700 800 900 10 100 1000 Output Current (mA) CH2 LX2 and Output Voltage Ripple CH2 LX2 and Output Voltage Ripple VIN = 3.3V, VOUT = 1.8V, IOUT = 300mA VIN = 4.2V, VOUT = 2.5V, IOUT = 400mA LX2 (2V/Div) Output Current (mA) VOUT (10mV/Div) VOUT (10mV/Div) LX2 (2V/Div) 0 Time (1μs/Div) DS9911-05 April 2011 Time (1μs/Div) www.richtek.com 13 RT9911 CH2 Load Transient Response CH2 Load Transient Response VIN = 3.3V, VOUT = 1.8V VOUT (20mV/Div) IOUT (100mA/Div) IOUT (200mA/Div) VOUT (20mV/Div) VIN = 3.0V, VOUT = 2.5V Time (1ms/Div) Time (1ms/Div) CH2 Output Voltage vs. VDDM Voltage CH2 Load Transient Response 1.84 VIN = 4.2V, VOUT = 2.5V VIN = 3.3V, VOUT = 1.8V, IOUT = 250mA 1.83 IOUT (200mA/Div) Output Voltage (V) VOUT (20mV/Div) 1.82 1.81 1.80 1.79 1.78 1.77 1.76 1.75 1.74 2.4 Time (1ms/Div) 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 VDDM Voltage (V) CH2 Buck Output Voltage vs. Output Current 1.815 3.360 1.814 3.350 1.813 Output Voltages (V) Output Voltages (V) CH2 Buck Output Voltage vs. Output Current 3.370 3.340 3.330 3.320 3.310 3.300 3.290 3.280 VIN = 3.7V, VOUT = 3.3V 3.270 1.812 1.811 1.810 1.809 1.808 1.807 1.806 VIN = 3.7V, VOUT = 1.8V 1.805 0 100 200 300 400 500 600 700 800 900 1000 100 0 Output Current (mA) www.richtek.com 14 0 100 200 300 400 500 600 700 800 900 1000 100 0 Output Current (mA) DS9911-05 April 2011 RT9911 CH3 Boost Efficiency vs. Output Current 100 90 90 80 80 70 VIN = 3.2V = 2.5V = 2.0V = 1.5V 60 50 Efficiency (%) Efficiency (%) CH3 Boost Efficiency vs. Output Current 100 40 30 60 50 40 30 20 20 10 VIN = 4.5V = 3.8V = 3.2V = 2.5V = 2.0V = 1.5V 70 10 VOUT = 3.3V VOUT = 5V 0 0 10 100 10 1000 100 1000 Output Current (mA) Output Current (mA) CH3 Boost Efficiency vs. Output Current CH3 LX3 and Output Voltage Ripple 100 VIN = 1.8V, VOUT = 3.3V, IOUT = 400mA 90 LX3 (2V/Div) 70 60 VIN = 3.0V Async = 2.4V Async = 1.5V Async = 3.0V Sync = 2.4V Sync = 1.5V Sync 50 40 30 20 10 0 VOUT (20mV/Div) Efficiency (%) 80 VOUT = 3.3V 10 100 1000 Time (1μs/Div) Output Current (mA) CH3 LX3 and Output Voltage Ripple CH3 Load Transient Response VIN = 1.8V, VOUT = 5V, IOUT = 350mA Time (1μs/Div) DS9911-05 April 2011 IOUT (200mA/Div) VOUT (20mV/Div) LX3 (2V/Div) VOUT (100mV/Div) VIN = 3.0V, VOUT = 3.3V Time (1ms/Div) www.richtek.com 15 RT9911 CH3 Boost Output Voltage vs. VDDM Voltage 3.30 CH3 Boost Output Voltage vs. VDDM Voltage 5.08 VIN = 2.5V, VOUT = 3.3V, IOUT = 250mA 3.29 3.28 5.06 Output Voltage (V) Output Voltage (V) VIN = 2.5V, VOUT = 5.0V, IOUT = 250mA 5.07 3.27 3.26 3.25 3.24 3.23 3.22 5.05 5.04 5.03 5.02 5.01 5.00 3.21 4.99 3.20 4.98 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6 2.4 2.8 3.2 VDDM Voltage (V) 5.010 80 5.005 Efficiency (%) Output Voltage (V) 90 5.000 4.995 4.990 60 50 40 20 10 4.975 0 0.4 0.5 0.6 0.7 0.8 0.9 1 VOUT = 12V 1 10 Output Current (A) Output Current (mA) CH4 LX4 and Output Voltage Ripple CH4 Load Transient Response 100 VIN = 1.8V, VOUT = 12V IOUT (20mA/Div) VOUT (20mV/Div) LX4 (5V/Div) VOUT (100mV/Div) VIN = 1.8V, VOUT = 12V, IOUT = 30mA Time (1μs/Div) www.richtek.com 16 5.6 30 4.980 0.3 5.2 VIN = 4.5V = 3.8V = 3.2V = 2.5V = 2.0V = 1.5V 70 4.985 0.2 4.8 CH4 Boost Efficiency vs. Output Current VIN = 3.7V, VOUT = 5V 0.1 4.4 100 5.015 0 4 VDDM Voltage (V) CH3 Boost Output Voltage vs. Output Current 5.020 3.6 Time (1ms/Div) DS9911-05 April 2011 RT9911 CH4 Output Voltage vs. VDDM Voltage CH4 Output Voltage vs. VDDM Voltage 11.88 15.42 VIN = 2.5V, PVDD5 = 3.3V, IOUT = 30mA 11.87 11.86 15.40 Output Voltage (V) Output Voltage (V) VIN = 2.5V, PVDD5 = 3.3V, IOUT = 30mA 15.41 11.85 11.84 11.83 11.82 11.81 11.80 11.79 15.39 15.38 15.37 15.36 15.35 15.34 15.33 11.78 15.32 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 2.4 2.8 3.2 VDDM Voltage (V) 70 Efficiency (%) Output Voltages (V) 15.765 15.760 15.755 15.750 15.745 50 30 20 10 15.730 0 40 50 60 70 80 90 VIN = 1.5V = 2.0V = 2.5V = 4.5V = 3.2V = 3.8V 40 15.735 30 100 VOUT = -8V 1 10 100 Output Current (mA) Output Current (mA) CH5 LX5 and Output Voltage Ripple CH5 Load Transient Response VIN = 1.8V, VOUT = -8V IOUT (20mA/Div) VOUT (20mV/Div) VOUT (100mV/Div) LX5 (5V/Div) VIN = 1.8V, VOUT = -8V, IOUT = 50mA Time (1μs/Div) DS9911-05 April 2011 5.6 60 15.740 20 5.2 90 80 10 4.8 CH5 Inverting Efficiency vs. Output Current 15.770 0 4.4 100 VIN = 3.7V, VOUT = 15.5V 15.775 4 VDDM Voltage (V) CH4 Boost Output Voltage vs. Output Current 15.780 3.6 Time (1ms/Div) www.richtek.com 17 RT9911 CH5 Output Voltage vs. VDDM Voltage CH5 Output Voltage vs. VDDM Voltage -8.02 -6.02 VIN = 3.0V, PVDD5 = 3.3V, IOUT = 30mA -8.03 -6.03 -6.04 Output Voltage (V) -8.04 Output Voltage (V) VIN = 3.0V, PVDD5 = 3.3V, IOUT = 30mA -8.05 -8.06 -8.07 -8.08 -8.09 -6.05 -6.06 -6.07 -6.08 -6.09 -8.10 -6.10 -8.11 -6.11 -6.12 -8.12 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 2.4 5.6 2.8 3.2 4 4.4 4.8 5.2 5.6 VDDM Voltage (V) VDDM Voltage (V) CH6 Efficiency vs. Input Voltage CH5 Output Voltage vs. Output Current -8.152 100 -8.151 90 -8.150 80 -8.149 70 Efficiency (%) Output Voltages (V) 3.6 -8.148 -8.147 -8.146 -8.145 IOUT = 20mA 60 50 40 30 20 -8.144 -8.143 10 VIN = 3.7V, VOUT = -8V 0 -8.142 0 -10 -20 -30 -40 -50 -60 -70 -80 1.5 -90 -100 2 2.5 3 3.5 4 4.5 Loading Current (mA) Input Voltage (V) CH6 LX6 and Output Voltage Ripple CH7 Load Transient Response VIN = 2.5V, VOUT = 1.8V IOUT (200mA/Div) VOUT (20mV/Div) LX6 (5V/Div) VOUT (10mV/Div) VIN = 1.8V, VOUT = 3 x WLED, IOUT = 20mA Time (1μs/Div) www.richtek.com 18 5 Time (1ms/Div) DS9911-05 April 2011 RT9911 CH1 and CH2 Power Sequence VOUT_Ch5 (5V/Div) VOUT_Ch2 (2V/Div) VOUT_Ch4 (5V/Div) VOUT_Ch1 (2V/Div) EN4/EN5 (2V/Div) EN1/EN2 (2V/Div) CH4 and CH5 Power Sequence Start Up, VIN = 2.5V Time (1ms/Div) Start Up, VIN = 2.5V Time (2ms/Div) Feedback Voltage vs. Temperature 1.04 Feedback Voltage (V) 1.00 VFB4, VFB6 0.96 0.92 0.88 0.84 VFB1, VFB2, VFB3 0.80 0.76 0.72 -40 -20 0 20 40 60 80 100 Temperature (°C) DS9911-05 April 2011 www.richtek.com 19 RT9911 Applications Information The RT9911 includes the following six DC/DC converter channels to build a multiple-output power-supply system. CH1 : Selectable step-up or step-down synchronous current mode DC/DC converter with internal power MOSFETs. CH2 : Step-down synchronous current mode DC/DC converter with internal power MOSFETs. CH3 : Step-up asynchronous current mode DC/DC controller to drive external power MOSFETs. CH4 : Step-up asynchronous voltage mode DC/DC controller. CH5 : Inverting DC/DC voltage mode controller. CH6 : DC/DC voltage mode controller for WLED as well as conventional boost application; provides open LED OVP protection. CH1 : Selectable Step-up or Step-down Converter CH1 is selectable as step-up (SELECT pin = logic high) or step-down (SELECT pin = logic low). Step-up : With internal MOSFETs and synchronous rectifier, the efficiency is up to 95%. The converter always operates at fixed frequency PWM mode and CCM (continuous current mode). Step-down : With internal MOSFETs and synchronous rectifier, the efficiency is up to 95%. The converter always operates at fixed frequency PWM mode and CCM. While the input voltage is close to output voltage, the converter enters low dropout mode. Duty could be as long as 100% to extend battery life. See Figure 3(a) for detailed functional block. CH3 : Step-up DC/DC Controller With external MOSFETs and a synchronous rectifier, the efficiency is up to 97%. The converter always operates at fixed frequency PWM mode and CCM. The threshold of current limit is estimated by RDS(ON) of external NMOS. See Protections for detailed information and detailed functional block in Figure 3(c). CH4, CH6 : Step-up DC/DC Controller CH4 and CH6 are fixed frequency voltage mode PWM controllers. EXT4 and EXT6 pins are designed to drive external NMOS switch. CH6 is optimized for WLED application. CFB6 is current-sensing feedback, and VFB6 provides over voltage protection (WLED open circuit). See Protections for detailed information and detailed functional block in Figure 3(d for CH4 and e for CH6). CH5 : Inverting Controller CH5 is a voltage mode, fixed frequency PWM controller to generate negative output voltage. EXT5 is designed to drive external PMOS switch. To turn off PMOS completely, please note that PVDD5 should not be lower than the source voltage of PMOS. See Figure 3(f) for detailed functional block. Reference Voltage RT9911 provides a precise 1V reference voltage with souring capability 100μA. Connect a 1μF ceramic capacitor from VREF pin to GND. Reference voltage is enabled by connecting EN5 to logic high. CH2 : Step-down DC/DC Converter With internal MOSFETs and synchronous rectifier, the efficiency is up to 95%. The converter always operates at fixed frequency PWM mode and CCM. While the input voltage is close to output voltage, the converter enters low dropout mode. Duty could be as long as 100% to extend battery life. See Figure 3(b) for detailed functional block. www.richtek.com 20 DS9911-05 April 2011 RT9911 PVDD2 PVDD1 OSC COMP1 0.8V FB1 SELECT S Q + + - - Logic R Driver LX1 OSC COMP2 0.8V FB2 Current Sense S Q + + - - R Logic Driver Current Sense Slope compensation PGND1 Fault Protection Slope compensation Figure 3(a) PGND2 Fault Protection Figure 3(b) PVDD3 OSC COMP3 0.8V FB3 CS3 S Q + + - - LX2 DRP3 Logic R Driver PVDD5 OSC COMP4 1.0V FB4 + - DRN3 Current Sense Slope compensation PGND2 Fault Protection S Q + - R Logic Driver EXT4 GND Triangle Wave Figure 3(d) Figure 3(c) PVDD5 OSC COMP6 CFB6 0.2V EN6 + + - S Q + - Logic R Driver EXT6 PVDD5 OSC COMP5 FB5 GND + - S Q + - R Logic Driver EXT5 Diming Control Triangle Wave Fault Protection GND GND Triangle Wave Figure 3(e) Figure 3(f) Figure 3. Detailed Functional Block for each channel DS9911-05 April 2011 www.richtek.com 21 RT9911 VBAT VDDM (VS 3.3V) EN1 to EN6 VS 3.3V T1r T1d VCORE 1.8V VI/O 3.3V T2d T2r Motor 5V T3d T3r CCD 12V CCD - 8V T4d T4r T5d T5r WLED T6d Note : z Please refer to Figure 1 for application Information. z Timing sequence should be controlled by EN pins. T6r Figure 4. Timing Diagram Calculation method: Units : T in second, C in Farad, R in Ohm T3r = (0.5V x D3 + 0.8A x RDS(ON)_N x C33 /3.6μA @ No load C31 to C36 : Compensation capacitor of CH1 to CH6. T4r = (1.0V x D4) x C34 / 1μA @ No load T1d = 0.7V x C31 / 2μA (CH1 Boost) T5r = (1.0V x D5) x C35 / 1μA @ 1mA min. load T1d = 0.7V x C31 / 2μA (CH1 Buck) T6r = (0.25V x D6) x C36 / 2.6μA @ 4 WLEDs T2d = 0.35V x C32 / 2μA where T3d = 0.7V x C33 / 2μA D1 = 1 − (VBAT / VVS 3.3V) (Boost) T4d = 0.35V x C34 / 2μA D1 = VVS 3.3V / VBAT T5d = 0.85V x C35 / 2μA D2 = VVCORE 1.8V / VBAT T6d = 0.85V x C36 / 2μA D3 = 1 − (VBAT / VMotor 5V) Td1 to Td6 are precise value. Tr1 to Tr6 are approximation. T1r = (0.5V x D1 + 0.48A x RDS(ON)_N x C31 /1.25μA @ No load (Boost) (Buck) D4 = 1 − (VBAT / VCCD 12V) D5 = |VCCD -8V| / ( VBAT + |VCCD -8V|) T1r = (0.33V x D1 + 0.2A x RDS(ON)_P x C31 /1.25μA @ No load (Buck) D6 = 1 − (VBAT / VWLED) T2r = (0.33V x D2 + 0.2A x RDS(ON)_P x C32 /1.25μA @ No load T1r = (0.5 x (1−1.8/3.3) + 0.48 x 0.2) x 1nF / 1.25μA = 258μs www.richtek.com 22 Example : T1d = 0.7V x 1nF / 2μA = 350μs (Boost) DS9911-05 April 2011 RT9911 Oscillator Soft Start With internal soft start mechanism, the soft start time of each channel is proportional to the compensation capacitor. Refer to the soft start waveform in Figure 4 for typical application. Oscillator Frequency vs. RRT 2500 Oscillator Frequency (kHz)1 The internal oscillator synchronizes CH1 to CH6 with fixed operation frequency. The frequency could be set by connecting resistor between RT pin to GND. See Figure 5 to adjust frequency. 2250 2000 1750 1500 1250 1000 750 500 250 0 Protection 10 RT9911 provides versatile protection functions. Protection type, threshold and protection methods are summarized in Table 1. 100 1000 RRT (kΩ) Figure 5. Adjust Frequency Table 1 VDDM CH1: Boost Protection Threshold (typical) type Refer to Electrical spec Over Voltage Protection Current Limit Current Limit CH1: Under Voltage Buck Protection Over Voltage Protection Current Limit CH2 Under Voltage Protection Over Voltage Protection CH3 CH6 Thermal Current Limit VDDM > 6.5V Disable all channels NMOS current> 2.5A NMOS latched off PMOS current > 2.0A FB1 < 0.4V FB1 > 1.0V PMOS current > 2.0A FB2 < 0.4V FB2 > 1.0V CS3 > 0.3V, see below Note Over Voltage VFB6 > 1.0V, see Protection Figure 8 Thermal shutdown Protection methods Temperature > 180°C PMOS latched off and all channels shutdown NMOS, PMOS latch off and all channels shutdown NMOS, PMOS latch off and all channels shutdown PMOS latched off and all channels shutdown NMOS, PMOS latch off and all channels shutdown NMOS, PMOS latch off and all channels shutdown NMOS latched off Reset method Restart if VDDM < 6.5V Automatic reset at next clock cycle VDDM power reset VDDM power reset VDDM power reset VDDM power reset VDDM power reset VDDM power reset Automatic reset at next clock cycle NMOS off VFB6 < 1.0V All channels stop switching Temperature < 160°C Note : If RDS(ON) x Iinductor > 0.3V, then current limit happens. For example, if select NMOS( AOS3402), RDS(ON) =110mΩ (at VGS = 2.5V), then current limt happens if Iinductor > 2.73A. DS9911-05 April 2011 www.richtek.com 23 RT9911 VBAT VBAT VDDM WLED EXT6 10µA R LX3 CH3 PWM VFB6 CS3 - 1V 50µA Iinductor DRN3 + CH6 PWM CFB6 Figure 6. CH3 Current Limit Setting Figure 8. CH6 Over Voltage Protection Method (VWLED > 50μA x R+1V, protection happens) RT9911 Component Selection for Compensation : CH1 Sync-Boost (Select Pin = High Logic) : CH1 sync-boost converter employs current-mode control to simplify the control loop compensation. There is a RHPZ (Right Hand Plane Zero) appeared in the loop-gain frequency response when a boost converter operates with continuous inductor current (typically the case), we also call it works in CCM (Continuous Current Mode). For stability, cross over frequency (fC), unity gain frequency, must lower than this RHPZ frequency. The fixed parameters for CH1 boost compensation are as follows : z Transconductance (from FB to COMP), GM = 200μs z Current sense transresistance, RCS = 0.4V/A z Feedback voltage, VFB = FB = 0.8V COMP CP RC 0.8V R1 R2 VIN, input voltage. z VOUT, desired output voltage z IOUT(MAX.), maximum output load z FOSC, operating frequency z L, inductance z RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) TDRP(%), Transient droop. The results we will get for CH1 boost compensation are as follows: RESR IOUT z R2, the voltage divider resistor in between FB and ground. z CF, feedforward capacitor in parallel with R1. z RC, compensation resistor on COMP pin. COUT z Figure 7 R1, the voltage divider resistor in between VOUT and FB. z z FB CC www.richtek.com 24 CF z z VOUT + GM - The input parameters for CH1 boost compensation are as follows: z CC, compensation capacitor in series with Rc and connect to ground. CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF). COUT, output capacitance. This compensation is based on ceramic output capacitor. DS9911-05 April 2011 RT9911 The major steps for getting above results : ⎞ VFB 1. R2 = R1 x ⎛⎜ ⎜ (VOUT - VFB) ⎟⎟ ⎝ ⎠ RLOAD GM ⎛ VFB ⎞ RCS x⎜ ⎟ x (1 − D) = 6.3nF. 4. CC = 2πfC ⎝ VOUT ⎠ Choose 6.8nF. Half-load transient means load from 0.25A to 0.5A transient. So, dI=0.5 − 0.25=0.25A 2. Find RHPZ(Right Hand Plan Zero) location. RHPZ(Boost) = RLOAD x RLOAD = VOUT IOUT(MAX.) 2 (1 - D) , Where 2πL , D = Duty Cycle = 1 - VIN VOUT 3. Set fC (cross over frequency) sufficiently below RHPZ. For example : fC = RHPZ/6 V FB ⎛ R LOAD ⎞ GM x x (1 - D) ⎟x 4. Get C C = ⎜ ⎝ R CS ⎠ 2π f C V OUT 5. Select Rc based on the allowed transient droop. 1 RCS RC = dI x ( )x (1- D) GM x dVFB , where dI = transient step, dVFB = TDRP(%) x VFB RC x CC 6. Get COUT = RLOAD 7. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffz VOUT ratio = = ffp VFB fC 8. Get CF by placing ffp on fC and ffz therefore on . ratio 1 fC Cf = , where ffz = 2 x π x ffz x R1 ratio 9. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). RESR CP = COUT . CP can be ignore if CP < 10pF. RC Example : Set R1 = 470kΩ, VIN = 1.8V, VOUT = 3.3V, VFB = 0.8V, IOUT(MAX.) = 0.5A, fOSC = 500kHz, L = 4.7μH, RESR = 5mΩ, and half-load transient droop is 5%. Results: 1. R2 = R1 VFB 0.8 = 470k = 150k Ω VOUT - VFB 3.3 - 0.8 2 (1 - D) = 66.3kHz, where 2πL VOUT VIN RLOAD = = 6.6Ω , (1 - D) = = 0.54 IOUT(MAX) VOUT 2. RHPZ(Boost) = RLOAD 3. fC = RHPZ = 11kHz 6 dVFB = TDRP(%) x VFB = 5% x 0.8 = 0.04V. Thus, ⎛ 1 ⎞ ⎟ x RCS dI⎜⎜ (1 - D) ⎟⎠ ⎝ = 23kΩ 5. RC = GM x dVFB 6. COUT = 7. ratio = ffp VOUT 3.3 = = = 4.1 ffz VFB 0.8 1 = 126pF, where 2π × ff Z × R1 fC 11k ff Z = = = 2.68kHz ratio 4.1 8. CF = Choose CF = 150pF COUT x RESR 22μF x 0.005 = = 4.8pF , 9. CP = RC 23k which is less than 10pF. So, It can be ignored. CH1 Sync-Buck (Select Pin = Low Logic) and CH2 Sync-Buck : CH1 sync-buck (select pin=low logic) and CH2 sync-buck are converters employ current-mode control to simplify the control loop compensation. There is no RHPZ (Right Hand Plan Zero) in the buck topology but there is a high frequency pole f HP >= f OSC /π . The f C (cross over frequency) is chosen sufficient less than fHP. The fixed parameters for CH1 and CH2 buck compensation are as follows: z Transconductance (from FB to COMP), GM = 200μs z Current sense transresistance, RCS = 0.3V/A z Feedback voltage, VFB = FB = 0.8V The input parameters for CH1 and CH2 buck compensation are as follows: z DS9911-05 April 2011 RC x CC 23k x 6.8n = = 22 μF . RLOAD 6 .6 R1, the voltage divider resistor in between VOUT and FB. www.richtek.com 25 RT9911 z VIN, input voltage. z VOUT, desired output voltage z IOUT(MAX.), maximum output load z fOSC, operating frequency 8. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). COUT x RESR CP = . CP can be ignore if CP < 10pF. RC Example : Set R1 = 470kΩ, VIN = 3V, VOUT = 1.8V, z L, inductance VFB = 0.8V, IOUT(MAX.) = 0.5A, fOSC = 500kHz, L = 4.7μH, RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) RESR = 5mΩ, and half-load transient droop is 5%. TDRP(%), Transient droop. Results : z z The results we will get for CH1 boost compensation are as follows: z R2, the voltage divider resistor in between FB and ground. z CF, feedforward capacitor in parallel with R1. z RC, compensation resistor on COMP pin. z z z CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) COUT, output capacitance. This compensation is based on ceramic output capacitor. 1. R2 = R1 x 2. fC = VFB 0.8 = 470k x = 376k Ω VOUT - VFB 1.8 - 0.8 fHP fOSC = = 40kHz 4 4π RLOAD GM VFB x x = 4.25nF, where RCS 2πfC VOUT VOUT RLOAD = = 3.6Ω IOUT(MAX.) 3. CC = Choose 4.7nF. Half-load transient means load from 0.25A to 0.5A transient. So, dI = 0.5 − 0.25=0.25A dVFB = TDRP(%) x VFB = 5% x 0.8 = 0.04V. The major steps for getting above results : VFB 1. R2 = R1 VOUT - VFB 2. Set fc (cross over frequency) sufficiently below fOSC. fHP For example : fC = 4 3. CC = RLOAD GM VFB x x RCS 2πfC VOUT dI x RCS 4. RC = GM x dVFB , where dI = transient step, dVFB = TDRP(%) x VFB RC x CC RLOAD 6. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffp VOUT ratio = = ffz VFB fC 7. Get CF by placing ffp on fC and ffz therefore on . ratio 1 fC CF = , where ff Z = . 2π × ff Z × R1 ratio 5. Get COUT = www.richtek.com 26 Thus, 4. RC = dI RCS = 9.4k Ω , choose 10k Ω. GM x dVFB 5. COUT = RC x CC = 10k x 3.9nF = 10.8 μF. Choose 10 μF. RLOAD 3 .6 6. ratio = ffp VOUT 1.8 = = = 2.25 ffz VFB 0.8 1 = 15.2pF, where 2π × ff Z × R1 fC 50k ff Z = = = 22.2kHz ratio 2.25 7. CF = Choose CF = 22pF COUT x RESR 10 μ x 0.005 8. CP = = = 5pF , RC 10k which is less than 10pF. So, It can be ignored. DS9911-05 April 2011 RT9911 CH3 Syn Boost Controller with External MOSFET : CH3 boost controller driving external logic level MOSFET employs current-mode control to simplify the control loop compensation. There is a RHPZ (Right Hand Plan Zero) appeared in the loop-gain frequency response when a boost converter operates with continuous inductor current (typically the case), we also call it works in CCM (Continuous Current Mode). For stability, cross over frequency (fC), unity gain frequency, must lower than this RHPZ frequency. The fixed parameters for CH3 boost compensation are as follows : z Transconductance (from FB to COMP), GM = 200μs z Feedback voltage, VFB = FB = 0.8V The input parameters for boost compensation are as follows : z z RDS(ON), the NMOSFET RDS(ON), which is use to find transresistance, RCS. R1, the voltage divider resistor in between VOUT and FB. z COUT, output capacitance. This compensation is based on ceramic output capacitor. The major steps for getting above results : 1. RCS = 2 x RDS(ON) The rest of the steps are the same as sync-boost. CH4 Asyn-Boost Controller with External MOSFET CH4 is an asyn-boost controller driving external logic level N type MOSFET, which employs voltage mode control to regulate the output voltage. Compensation depends on designing the loading range working in discontinuous or continuous inductor current mode. (DCM or CCM). Asyn-Boost in DCM : We call it DCM because inductor current falls to zero on each switch cycle. The benefit of designing in DCM is the simple loop compensation, which has no RHPZ (Right Hand Plan Zero) and conjugate double pole in the frequency domain to worry about, but has a single load pole instead. However, the output ripple and efficiency are worse than in CCM (Continuous Inductor Current). If the loading is around tens of mA, it is not bad to design in DCM with less impact on the output ripple and efficiency, but gain more easy to stabilize the control loop. z VIN, input voltage. z VOUT, desired output voltage z IOUT(MAX.), maximum output load z FOSC, operating frequency The fixed parameters for CH4 asyn-boost in DCM compensation are as follows: z L, inductance z Transconductance (from FB to COMP), GM = 200us. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) z Internal voltage ramp to decide duty cycle, VP = 1V. z Feedback voltage, VFB = FB = 1V z z TDRP(%), Transient droop. VOUT The results we will get for boost compensation are as follows : z RCS, the transresistance of current sense. z R2, the voltage divider resistor in between FB and ground. z CF, feedforward capacitor in parallel with R1. z RC, compensation resistor on COMP pin. z z CC, compensation capacitor in series with RC and connect to ground + GM - COMP CP RC 1V R1 FB R2 CF RESR IOUT COUT CC Figure 9 CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) DS9911-05 April 2011 www.richtek.com 27 RT9911 The input parameters for CH4 asyn-boost in DCM compensation are as follows : z R1, the voltage divider resistor in between VOUT and FB. z VIN, input voltage. z VOUT, desired output voltage z IOUT(MAX.), maximum output load z fOSC, operating frequency z L, inductance z z COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH4 asyn-boost in DCM compensation are as follows : z R2, the voltage divider resistor in between FB and ground. z CF, feedforward capacitor in parallel with R1. z RC, compensation resistor on COMP pin. z z CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) The major steps for getting above results : VFB 1. R2 = R1 x VOUT - VFB 2. Select suitable inductor to ensure IOUT(MIN.) works in DCM, which is let inductor current falls to zero on each switch cycle. VIN x D x (1 - D) L< 2 x IOUT(MAX.) x fOSC 3. Set fC sufficient below fOSC. fOSC For example: fC = or lower 10 2 x M-1 , 2π x (M - 1) x RLOAD x COUT VOUT VOUT where M = , RLOAD = . VIN IOUT(MAX.) 4. Find the load pole : fLP = fC x VP VOUT M-1 , where Gdod = 2 x x , 5. Get RC = fLP GM x Gdod D 2 x M-1 www.richtek.com 28 which is duty to VOUT transfer function. VIN D = duty cycle = 1 VOUT RLOAD RC by letting comp zero = load pole. 6. Get CC = COUT x 7. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffp VOUT ratio = = ffz VFB fC 8. Get CF by placing ffp on fC and ffz therefore on . ratio CF = 1 fC , where ff Z = . 2π × ff Z × R1 ratio 9. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). CP = COUT x RESR . CP can be ignore if CP < 10pF. RC Asyn-boost in CCM : We call it CCM because inductor current is always continuous in operation. The benefit of designing in CCM is lower VOUT and inductor current ripple and higher efficiency from the lower coil loss, but with the expense of larger inductor size and cost and the control loop comes with a RHPZ (Right Hand Plan Zero) and a conjugate double pole in the frequency domain to worry about. The fixed parameters for CH4 asyn-boost in CCM compensation are as follows : z Transconductance (from FB to COMP), GM = 200μs z Internal voltage ramp to decide duty cycle, VP = 1V z Feedback voltage, VFB = FB = 1V The input parameters for CH4 asyn-boost in CCM compensation are as follows : z R1, the voltage divider resistor in between VOUT and FB. z VIN, input voltage. z VOUT, desired output voltage z IOUT(MAX.), maximum output load z IOUT(MIN.), minimum output laod z fOSC, operating frequency DS9911-05 April 2011 RT9911 z z z L, inductance COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH4 asyn-boost in CCM compensation are as follows: z R2, the voltage divider resistor in between FB and ground. z CF, feedforward capacitor in parallel with R1. z RC, compensation resistor on COMP pin. z z CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) The major steps for getting above results : VFB 1. R2 = R1 x VOUT - VFB 2. Select suitable inductor to ensure IOUT(MIN.) works in CCM, VIN x D x (1 - D) L> 2 x IOUT(MIN.) x fOSC 3. Find RHPZ(Right Hand Plan Zero) location. RHPZ(Boost) = RLOAD RLOAD = VOUT IOUT(MAX) (1 - D)2 , where 2πL , D = duty cycle = 1 - VIN VOUT 4. Set fC (cross over frequency) sufficiently below RHPZ. RHPZ or lower. For example : fC = 6 2 x M-1 5. Find the load pole : fLP = , 2π x (M - 1) x RLOAD x COUT VOUT VOUT where M = , RLOAD = . VIN IOUT(MAX.) fC x VP VIN f LP Get R , where Gdoc = C = , 6. GM x Gdoc (1 - D)2 which is duty to VOUT transfer function. VIN D = duty cycle = 1 . VOUT 1- D , 7. Find fcdp = 2π x (LC)2 which is the conjugate double pole from LC filter. 1 to cancel one of the double pole. 8. CC = 2π x fcdp x RC 9. Find Cf by placing its zero on fcdp to cancel another double pole. 1 CF = . 2π × fcdp × R1 10.Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). RESR CP = COUT x . CP can be ignore if CP < 10pF. RC CH5 Asyn-Inverter Controller with External MOSFET CH5 is an asyn-inverter controller driving external logic level P type MOSFET, which employs voltage mode control to regulate the output voltage. Compensation depends on designing the loading range working in discontinuous or continuous inductor current mode. (DCM or CCM). Asyn-Inverter in DCM : We call it DCM because inductor current falls to zero on each switch cycle. The benefit of designing in DCM is the simple loop compensation, which has no RHPZ (Right Hand Plan Zero) and conjugate double pole in the frequency domain to worry about, but has a single load pole instead. However, the output ripple and efficiency are worse than in CCM (Continuous Inductor Current). If the loading is around tens of mA, it is not bad to design in DCM with less impact on the output ripple and efficiency, but gain more easy to stabilize the control loop. The fixed parameters for CH5 asyn-inverter in DCM compensation are as follows: z Transconductance (from FB to COMP), GM = 200μs z Internal voltage ramp to decide duty cycle, VP = 1V z Feedback voltage, VFB = FB = 0V z Reference voltage, VREF = 1V VOUT + GM - COMP CP RC 0V R1 CF FB R2 CC RESR IOUT COUT VREF = 1V 20k 4.7uF Figure 10 DS9911-05 April 2011 www.richtek.com 29 RT9911 The input parameters for CH5 asyn-inverter in DCM compensation are as follows : z R1, the voltage divider resistor in between VOUT and FB. z VIN, input voltage. z VOUT, desired output voltage z IOUT(MAX.), maximum output load z fOSC, operating frequency z L, inductance z z COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH5 asyn-inverter in DCM compensation are as follows : z R2, the voltage divider resistor in between FB and VREF. z CF, feedforward capacitor in parallel with R1. z RC, compensation resistor on COMP pin. z z fC x VP VOUT f LP Get R , where Gdod = , C= 5. GM x Gdod D CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) The major steps for getting above results : VREF - VFB . If R1 = 1MΩ and VOUT = (-8)V 1. R2 = R1 x VFB − VOUT 1- 0 then R2 = 1M x = 125k Ω 0 - (-8) 2. Select suitable inductor to ensure IOUT(MIN.) works in DCM, which is let inductor current falls to zero on each switch cycle. L< VIN x (1 - D) 2 x IOUT(MAX.) x fOSC 3. Set fC sufficient below fOSC fOSC For example: fC = or lower 10 2 , 4. Find the load pole : fLP = 2π x RLOAD x COUT VOUT where RLOAD = . IOUT(MAX.) www.richtek.com 30 which is duty to Vout transfer function. D = duty cycle = abs(VOUT) . VIN + abs(VOUT) RLOAD RC by letting comp zero = load pole. 6. Get CC = COUT x 7. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffp abs(VOUT) + VREF ratio = = ffz VREF fC 8. Get CF by placing ffp on fC and ffz therefore on . ratio 1 fC CF = , where ff Z = . 2π × ff Z × R1 ratio 9. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). CP = COUT x RESR . CP can be ignore if CP < 10pF. RC Asyn-Inverter in CCM : We call it CCM because inductor current is always continuous in operation. The benefit of designing in CCM is lower VOUT and inductor current ripple and higher efficiency from the lower coil loss, but with the expense of larger inductor size and cost and the control loop comes with a RHPZ (Right Hand Plan Zero) and a conjugate double pole in the frequency domain to worry about. The fixed parameters for CH5 asyn-inverter in CCM compensation are as follows : z Transconductance (from FB to COMP), GM = 200us z Internal voltage ramp to decide duty cycle, VP = 1V z Feedback voltage, VFB = FB = 0V z Reference voltage, VREF = 1V The input parameters for CH5 asyn-inverter in CCM compensation are as follows : z R1, the voltage divider resistor in between VOUT and FB. z VIN, input voltage. z VOUT, desired output voltage z IOUT(MAX.), maximum output load DS9911-05 April 2011 RT9911 z IOUT(MIN.), minimum output laod z fOSC, operating frequency z L, inductance z z COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH5 asyn-inverter in CCM compensation are as follows : z R2, the voltage divider resistor in between FB and VREF. z CF, feedforward capacitor in parallel with R1. z RC, compensation resistor on COMP pin. z z 7. Find fcdp = , 2π x (LC)2 which is the conjugate double pole from LC filter. 1 to cancel one of the double pole. 8. CC = 2π x fcdp x RC 9. Find Cf by placing its zero on fcdp to cancel another double pole. 1 CF = . 2π × fcdp × R1 10.Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). CP = COUT x RESR . CP can be ignore if CP < 10pF. RC PCB Layout Considerations CC, compensation capacitor in series with RC and connect to ground z CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) z The major steps for getting above results : VREF - VFB . If R1 = 1MΩ and VOUT = (-8)V 1. R2 = R1 x VFB − VOUT 1- 0 then R2 = 1M x = 125k Ω 0 - (-8) 1- D z z The feedback netwok should be very close to the FB pin. The compensation network should be very close to the COMP pin and avoid through VIA. For CH3 current sense, CS should be close to the drain site of external NMOS. Keep high current path as short as possible. 2. Select suitable inductor to ensure IOUT(MIN.) works in CCM, VIN x (1 - D) L< 2 x IOUT(MIN.) x fOSC 3. Find RHPZ(Right Hand Plan Zero) location. (1 - D)2 D , where RHPZ(Boost) = RLOAD 2πL VOUT abs(VOUT) RLOAD = , D = duty cycle = IOUT(MAX) VIN + abs(VOUT) 4. Set fC (cross over frequency) sufficiently below RHPZ. RHPZ For example: fC = or lower 6 2 , 5. Find the load pole : fLP = 2π x RLOAD x COUT abs(VOUT) where RLOAD = . IOUT(MAX.) fC x VP VIN , where Gdoc = , 6. Get RC = fLP GM x Gdoc (1 - D)2 which is duty to VOUT transfer function. D = duty cycle = abs(VOUT) VOUT VIN + abs(VOUT) DS9911-05 April 2011 www.richtek.com 31 RT9911 Outline Dimension D SEE DETAIL A D2 L 1 E E2 e b A 1 1 2 2 DETAIL A Pin #1 ID and Tie Bar Mark Options A3 A1 Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.800 1.000 0.031 0.039 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 D 5.950 6.050 0.234 0.238 D2 4.000 4.750 0.157 0.187 E 5.950 6.050 0.234 0.238 E2 4.000 4.750 0.157 0.187 e L 0.500 0.350 0.020 0.450 0.014 0.018 V-Type 40L QFN 6x6 Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: [email protected] Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. www.richtek.com 32 DS9911-05 April 2011