RT9902 Preliminary 4 Channel DC/DC Converters IC with High-Efficiency Step-Up and Step-Down General Description Features The RT9902 is a complete power supply solution for digital still cameras and other hand-held devices. It integrates a high-efficiency main step-up DC-DC converter, two highefficiency step-down converters, a charge pump, and a linear controller that drives an external P-MOSFET for linear regulator. The RT9902 is targeted for applications that use either two or three AA cells or a single lithiumion battery. z z z z z z z z z z Applications z z z Pin Configurations Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard) `100% matte tin (Sn) plating. ENM COMP2 FB2 24 VDD2 VDD3 LX3 2 23 VDD2 3 22 LX2 PGND3 SS RT 4 21 GND 7 18 LX2 PGND2 LX1 LX1 LDO_O 8 17 VDD1 GND 5 20 6 19 33 9 10 11 12 13 14 15 16 PGND1 `Suitable for use in SnPb or Pb-free soldering processes. 25 CX ments of IPC/JEDEC J-STD-020. 27 26 1 VDDC `RoHS compliant and compatible with the current require- 30 29 28 COMP3 CPFB Richtek Pb-free and Green products are : 32 31 EN1 Note : EN2 FB3 (TOP VIEW) EN3 Package Type QV : VQFN-32L 5x5 (V-Type) Digital Still Cameras PDAs Portable Devices COMP1 RT9902 z GND Ordering Information z FB1 RT9902 is available in VQFN-32L 5x5 package. z LFB The feature of the charge pump is to deliver few current to micro-controller when the system operates in the standby mode. RT9902 includes a linear controller with 0.8V reference voltage. An adjustable operating frequency (up to 1.4MHz) is utilized to get optimum size, cost, and efficiency. VDDM The main step-up DC-DC converter accepts inputs from 1.5V to 5.5V and build in 2.6A Internal switch. The two step-down DC-DC converters (CH2, CH3) accept inputs from 1.5V to 5.5V and regulate a resistor adjustable output from 0.8V to 5.5V. Each DC-DC converter has independent shutdown input. z 1.5V to 5.5V Battery Input Voltage Range Main step-up DC-DC Converter `1.5V to 5.5V Adjustable Output Voltage `Up to 90% Efficiency `2.6A, 0.3Ω Ω Internal Power Switch Two Step-Down DC-DC Converters `0.8V to 5.5V Adjustable Output Voltage `94% Efficiency `100% Duty Cycle Step-up Charge Pump for Micro-Controller Linear Controller for Linear Regulator Up to 1.4MHz Switching Frequency 1μ μA Supply Current in Shutdown Mode Programmable Soft Start Function Independent Enable Pin (CH1, CH2, CH3) External Compensation Network (CH1, CH2, CH3) Short Circuit Protection (CH1, CH2, CH3) Over Voltage Protection (CH2) 32-Lead VQFN Package RoHS Compliant and 100% Lead (Pb)-Free VQFN-32L 5x5 DS9902-10 August 2007 www.richtek.com 1 RT9902 Preliminary Typical Application Circuit 1-cell Li+ Battery 3V to 4.2V V BAT C17 C18 10μF 10μF C12 1μF L2 4.7μH C19 0.1μF C1 to C2 10μF x 2 L1 4.7μH 1.5V/500mA C7 100pF V BAT 32 D1 SS0520 C8 10μF 14 VDDC FB1 R3 680k 15 D2 C11 SS0520 22nF 1nF 13 R4 130k 25 ENM 26 EN1 29 30 R5 LDO_O CPFB LFB EN2 VDD2 EN3 12 COMP1 27 COMP2 R7 30k 1 COMP3 5 SS C16 1nF 6 R8 4 C21 to C24 10μF x 4 R11 51k Q1 SI2301 C25 100pF 10 23 24 L3 4.7μH C31 100pF 20 16 C20 100pF 8 21 LX2 22 FB2 C15 1nF R9 510k R10 150k RT9902 CX 30k R6 C14 1nF 20k 17 11 C12 Chip Enable C13 4.7nF VDD1 D3 SS0520 R12 470k V BAT C29 to C30 10μF x 2 C26 10μF V IN 3.52V V OUT 3.3V/500mA C27 to C28 10μF x 2 R13 150k 2.5V/500mA R14 470k 28 GND C9 to C10 10μF x 2 LX1 18 19 FB3 PGND3 IGBT Driver 5V/50mA LX3 PGND1 R2 220k 3 RT C3 to C6 10μF x 4 VDD3 PGND2 R1 200k 2 VDDM 9 V BAT C32 to C35 10μF x 4 R15 220k 7, 31 Exposed Pad (33) Figure 1. Typical Application Circuit from 1-cell Li+ Battery www.richtek.com 2 DS9902-10 August 2007 RT9902 Preliminary 1-cell Li+ Battery 3.4V to 4.2V V BAT C17 C18 10μF 10μF C12 1μF C19 0.1μF 9 L1 4.7μH 1.5V/500mA C7 100pF V BAT 14 25 Chip Enable 26 29 30 R5 20k R6 30k C13 4.7nF R7 C14 1nF 30k VDD1 VDDC 11 LDO_O CPFB LFB EN1 EN2 VDD2 EN3 12 COMP1 6 R8 4 20 16 R11 51k C25 100pF 23 24 L3 4.7μH C31 100pF 1 COMP3 C21 to C24 10μF x 4 Q1 SI2301 10 21 LX2 22 27 COMP2 C20 100pF 8 ENM 5 SS C16 1nF R9 680k R10 130k RT9902 CX FB2 C15 1nF 17 FB1 15 D2 22nF SS0520 13 R4 130k FB3 D3 SS0520 R12 470k V BAT C29 to C30 10μF x 2 V IN C26 10μF V OUT C27 to C28 10μF x 2 R13 150k 3.3V/500mA R14 470k 28 GND C11 1nF C12 LX1 18 19 PGND1 C9 to C10 10μF x 2 R3 680k LX3 32 D1 SS0520 C8 10μF IGBT Driver 5V/50mA 3 PGND2 R2 220k VDD3 PGND3 C3 to C6 10μF x 4 R1 200k 2 5V/500mA RT9701CB 5 VIN VOUT 4 EN VOUT 1 Chip Enable GND 10uF 2 3 VDDM C1 to C2 10μF x 2 RT V BAT L2 4.7μH C32 to C35 10μF x 4 R15 150k 7, 31 Exposed Pad (33) Figure 2. Typical Application Circuit from 1-cell Li+ Battery DS9902-10 August 2007 www.richtek.com 3 RT9902 Preliminary 2-AA Battery 2.0V to 3.4V C16 1μF C1 to C2 10μF x 2 L1 4.7μH 1.5V/300mA R1 200k C7 100pF R2 220k 32 D1 SS0520 V BAT 14 C8 10μF FB3 VDD1 FB1 C11 15 D2 SS0520 10nF 13 R4 15k Chip Enable ENM 26 EN1 30 R5 20k R6 30k 27 LFB EN2 VDD2 EN3 COMP1 LX2 COMP2 FB2 C14 1nF 5 SS C15 1nF 6 4 R8 20 16 C17 to C18 10μF x 2 I/O 3.3V/500mA R9 470k C19 C20 to C23 10μF x 4 100pF R10 150k R11 8 Q1 SI2301 10 R13 150k 23 24 21 22 R12 470k C24 100pF L3 4.7μH C30 100pF 1 COMP3 V BAT D3 SS0520 C25 10μF V IN V OUT C26 to C27 10μF x 2 3.3V C28 to C29 10μF x 2 2.5V/300mA R14 470k C31 to C34 10μF x 4 28 GND C12 4.7nF R7 30k C13 1nF 12 LDO_O CPFB 25 29 11 RT9902 CX PGND1 R3 47k C10 1nF L2 4.7μH 17 VDDC PGND2 C9 10μF LX1 18 19 LX3 PGND3 μC standby 3.3V/1mA VDD3 RT C3 to C6 10μF x 4 3 VDDM 9 2 V BAT R15 220k 7, 31 Exposed Pad (33) Figure 3. Typical Application Circuit from 2-AA Battery Supply www.richtek.com 4 DS9902-10 August 2007 RT9902 Preliminary Function Block Diagram VDDM VDDC CX CPFB EN CH1 Current-MODE Asynchronous Step-Up PWM CH4 Charge Pump LDO_O Linear Controller LFB EN PGND1 COMP1 FB1 EN2 VDD2 CH2 Current-MODE Synchronous Step-Down PWM LX2 PGND2 Buck2 PWM OSC RT EN1 VDD1 LX1 Boost Soft-Start OSC SS ENM Thermal Shutdown COMP2 FB2 EN3 VDD3 CH3 Current-MODE Synchronous Step-Down PWM LX3 PGND3 Buck3 COMP3 FB3 GND DS9902-10 August 2007 ENM EN1 EN2 EN3 Charge Pump CH1 + Linear Controller CH2 CH3 0 X X X Off Off Off Off 1 0 0 0 On Off Off Off 1 1 0 0 On On Off Off 1 1 1 0 On On On Off 1 1 1 1 On On On On www.richtek.com 5 RT9902 Preliminary Functional Pin Description Pin No. Pin Name Pin Function 1 COMP3 CH3 Feedback Compensation Pin. 2 VDD3 3 LX3 CH3 Power Input Pin. CH3 Switch Node. Drains of the internal P-Channel and N-MOSFET switches. Connect an inductor to LX3 pins together as close as possible. 4 PGND3 5 SS 6 RT 7 GND Analog Ground. 8 LDO_O Linear Controller Driver Output. 9 VDDM Device Input Power Pin. 10 LFB Linear Controller Feedback Input. 11 FB1 CH1 Feedback Input Pin. 12 COMP1 CH1 Feedback Compensation Pin. 13 CPFB Charge Pump Feedback Pin. 14 VDDC Charge Pump Power Input Pin. 15 CX Charge Pump External Driver Pin. 16 PGND1 Power Ground for CH1. 17 VDD1 CH1 Power Input Pin. Connect output of Boost to this pin. LX1 CH1 Switch Node. Connect an inductor to LX1 pins together as close as possible. PGND2 Power Ground for CH2. CH2 Switch Node. Drains of the internal P-MOSFET and N-MOSFET switches. Connect an inductor to LX2 pins together as close as possible. 18, 19 20 Power Ground for CH3. Sets the soft start interval of the converter. Connect a capacitor from this pin to ground. Frequency Setting Resistor Connection Pin. Frequency is 500kHz if RT pin not connected. 21, 22 LX2 23, 24 VDD2 25 ENM 26 EN1 27 COMP2 CH2 Feedback Compensation Pin. 28 FB2 29 EN2 30 EN3 CH2 Feedback Input. CH2 Enable Input. Tie this pin higher than 1.3V to enable CH2. Tie below 0.4V to turn off the CH2. CH3 Enable Input. Tie this pin higher than 1.3V to enable CH3. Tie below 0.4V to turn off the CH3. 31 GND Analog Ground. 32 FB3 CH3 Feedback Input. Exposed Pad (33) GND www.richtek.com 6 CH2 Power Input Pin. Whole Device Control Pin. Tie this pin higher than 1.3V to enable the device. Tie below 0.4V to turn off the device. CH1 Enable Input. Tie this pin higher than 1.3V to enable CH1. Tie below 0.4V to turn off the CH1. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. DS9902-10 August 2007 RT9902 Preliminary Absolute Maximum Ratings z z z z z z z z z z z z Supply Input Voltage (VDDM, VDD1, VDD2,VDD3,VDDC) ----------------------------------------------------- −0.3 to 7V LX1 Pin Switch Voltage ----------------------------------------------------------------------------------------- −0.3V to 7V LX2 Pin Switch Voltage ----------------------------------------------------------------------------------------- −0.3V to (VDD2 + 0.3V) LX3 Pin Switch Voltage ----------------------------------------------------------------------------------------- −0.3V to (VDD3 + 0.3V) CX Pin Switch Voltage ------------------------------------------------------------------------------------------ −0.3V to (VDDC + 0.3V) Other I/O Pin Voltage -------------------------------------------------------------------------------------------- −0.3V to (VDDM + 0.3V) Package Thermal Resistance VQFN-32L 5x5, θJA ----------------------------------------------------------------------------------------------- 34°C/W Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------- 260°C Operation Temperature Range --------------------------------------------------------------------------------- −40°C to 85°C Junction Temperature Range ----------------------------------------------------------------------------------- 0°C to 125°C Storage Temperature Range ----------------------------------------------------------------------------------- −65°C to 150°C ESD Susceptibility HBM (Human Body Mode) ------------------------------------------------------------------------------------- 2kV MM (Machine Mode) --------------------------------------------------------------------------------------------- 200V Electrical Characteristics (VDDM =3.3V, TA = 25°C, Unless Otherwise specification) Parameter Symbol Test Condition Min Typ Max Units -- 1.5 -- V 2.4 -- 5.5 V 5.5 V Supply Voltage Minimum Startup Voltage (Boost) VST VDDM Operating Voltage VVDDM VDDM Pin Voltage VVDD1 VDD1, VDD2, VDD3 Pin VVDD2, Voltage VDD1, VDD2, VDD3 Operating Voltage Boost loading < 1mA 1.5 VVDD3 VDDM Over Voltage Protection -- 6.5 -- V -- 0.01 1 μA -- 30 42 μA -- 250 350 μA -- 250 350 μA -- 250 350 μA Supply Current Shutdown Supply Current IOFF VENM pin=0V VVDDM = 3.3V, VENM = 3.3V, Charge Pump Current IVDDM VEN1 = 0V, VEN2 = 0V, VEN3 = 0V VVDDM = 3.3V, CH1 DC/DC Converter + Linear Controller Supply Current IVDDM VFB1 = 0.9V VENM = 3.3V, VEN1 = 3.3V, VEN2 = 0V, VEN3 = 0V VVDDM = 3.3V, CH2 DC/DC Converter Supply Current IVDDM VFB2 = 0.9V VENM = 3.3V, VEN1 = 0V, VEN2 = 3.3V, VEN3 = 0V VVDDM = 3.3V, CH3 DC/DC Converter Supply Current IVDDM VFB3 = 0.9V VENM = 3.3V, VEN1 = 0V, VEN2 = 0V, VEN3 = 3.3V To be continued DS9902-10 August 2007 www.richtek.com 7 RT9902 Parameter Preliminary Symbol Test Condition Min Typ Max Units Oscillator Operation Frequency Range FOSC 475 550 625 kHz CH1 Maximum Duty Cycle DMAX1 RT Open -- 85 90 % CH2 Maximum Duty Cycle DMAX2 -- -- 100 % CH3 Maximum Duty Cycle DMAX3 -- -- 100 % 0.788 0.8 0.812 V 0.78 0.8 0.82 V -- -- 12 mV GM -- 0.2 -- ms Compensation Source Current -- 22 -- μA Compensation Sink Current -- 22 -- μA N-MOSFET -- 300 400 mΩ VVDD1 = 3.3V 2 2.6 3 A N-MOSFET, VVDD2 = 3.3V -- 350 450 mΩ P-MOSFET, VVDD2 = 3.3V -- 350 450 mΩ 1.3 1.5 1.9 A N-MOSFET, VVDD3 = 3.3V -- 350 450 mΩ P-MOSFET, VVDD3 = 3.3V -- 350 450 mΩ 1.3 1.5 1.9 A 0.774 0.79 0.806 V 110 150 -- μA UVP Threshold Voltage @FB2, FB3 0.3 0.4 0.5 V Over Voltage Protection @FB2 0.95 1 -- V VVDDM = 3.3V -- 0.8 1.3 V VVDDM = 3.3V 0.4 0.8 -- V 140 180 -- °C -- 10 -- °C Feedback Voltage (CH1, CH2, CH3, CH4) Feedback Voltage Feedback Voltage (Charge Pump) VFB CH1, CH2, CH3 VCPFB CH4 Feedback Voltage ︱ΔVFB︱ CH1, CH2, CH3, CH4 3.0V < VDDM < 5.5V Error Amplifier Power Switch CH1 On Resistance of MOSFET RDS(ON) CH1 Current Limitation CH2 On Resistance of MOSFET RDS(ON) CH2 Current Limitation CH3 On Resistance of MOSFET VVDD2 = 3.3V RDS(ON) CH3 Current Limitation VVDD3 = 3.3V Linear Controller Feedback Voltage for Linear Controller VLFB LDO_O pin Sink Current VLDO_O = 1V UVP (CH2, CH3) & Over Voltage Protection (CH2) Control ENM, EN1, EN2, EN3 Input High Level Threshold ENM, EN1, EN2, EN3 Input Low Level Threshold Thermal Protection Thermal Shutdown TSD Thermal Shutdown Hysteresis ΔTSD www.richtek.com 8 DS9902-10 August 2007 RT9902 Preliminary Typical Operating Characteristics Oscillator Ferquency vs. RRT 1800 0.806 1600 Oscillator Frequecny (kHz) Reference Voltage (V) Reference Voltage vs. Temperature 0.808 0.804 0.802 0.8 0.798 0.796 0.794 1400 1200 1000 800 600 400 200 0.792 0 -50 -30 -10 10 30 50 70 90 0 100 200 300 Temperature (°C) 500 600 RRT (kΩ) Boost Output Voltage vs. VDD1 Voltage Boost Efficiency vs. Output Current 3.345 100 VBAT = 2.5V, VDDM = 3.3V, IOUT = 250mA VOUT = 3.3V 2.5V 80 2V 1.8V 70 60 Output Voltage (V) 3.34 VIN 3V 90 Efficiency (%) 400 3.335 3.33 3.325 3.32 3.315 3.31 Boost 3.305 50 1 10 100 1.5 1000 Output Current (mA) 3 3.5 4 4.5 5 5.5 Boost Load Transient Response Output Voltage Deviation (100mV/Div) VBAT = 2.5V, VDD1 = 3.3V, IOUT = 250mA 3.33 3.328 3.326 3.324 3.322 Load Current (200mA/Div) Output Voltage (V) 2.5 VDD1 Voltage (V) Output Voltage vs. VDDM Voltage 3.332 2 3.32 3.318 3.316 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 VIN = 1.8V, VOUT = 3.3V, @IOUT = 100mA to 400mA Time (1ms/Div) VDDM Voltage (V) DS9902-10 August 2007 www.richtek.com 9 RT9902 Preliminary Boost Load Transient Response VIN = 2.5V, VOUT = 3.3V, @IOUT = 100mA to 400mA Time (1ms/Div) Time (1ms/Div) Boost Load Transient Response Boost LX & Output Ripple VIN = 1.8V, VOUT = 3.3V, @IOUT = 100mA LX1 (2V/Div) VIN = 3V, VOUT = 3.3V, @IOUT = 100mA to 400mA Output Ripple (10mV/Div) Load Current (200mA/Div) Load Current (200mA/Div) VIN = 2V, VOUT = 3.3V, @IOUT = 100mA to 400mA Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) Output Voltage Deviation (100mV/Div) Output Voltage Deviation (100mV/Div) Boost Load Transient Response Time (1ms/Div) Time (1us/Div) Boost LX & Output Ripple Boost LX & Output Ripple Output Ripple (10mV/Div) Output Ripple (20mV/Div) Time (1us/Div) www.richtek.com 10 VIN = 2.5V, VOUT = 3.3V, @IOUT = 100mA LX1 (2V/Div) LX1 (2V/Div) VIN = 1.8V, VOUT = 3.3V, @IOUT = 300mA Time (1us/Div) DS9902-10 August 2007 RT9902 Preliminary Boost LX & Output Ripple Boost LX & Output Ripple VIN = 2.5V, VOUT = 3.3V, @IOUT = 400mA Output Ripple (10mV/Div) Output Ripple (20mV/Div) LX1 (2V/Div) LX1 (2V/Div) VIN = 3V, VOUT = 3.3V, @IOUT = 100mA Time (1us/Div) Time (1us/Div) Buck2 Efficiency vs. Output Current Boost LX & Output Ripple 100 VIN = 3V, VOUT = 3.3V, @IOUT = 400mA VOUT = 1.5V VIN = 2.2V Output Ripple (10mV/Div) LX1 (2V/Div) Efficiency (%) 90 80 VIN = 4.5V VIN = 2.5V VIN = 3V VIN = 3.8V 70 60 50 Time (1us/Div) 1 10 100 1000 Output Current (mA) Buck2 Efficiency vs. Output Current 100 Buck2 Efficiency vs. Output Current 100 VOUT = 1.8V VIN = 2.5V 90 VIN = 4.5 80 80 Efficiency (%) Efficiency (%) VOUT = 2.5V 90 VIN = 3V VIN = 4.5 VIN = 3.8V 70 70 60 VIN = 3.8V 50 VIN = 3V 60 40 30 50 1 10 100 Output Current (mA) DS9902-10 August 2007 1000 1 10 100 1000 Output Current (mA) www.richtek.com 11 RT9902 Preliminary Buck2 Output Voltage vs. VDD2 Voltage Buck2 Output Voltage vs. VDDM Voltage 1.82 1.82 VDD2 = 3.3V, IOUT = 250mA 1.818 1.816 1.816 Output Voltage (V) Output Voltage (V) VBAT = VDDM = 3.3V, IOUT = 250mA 1.818 1.814 1.812 1.81 1.808 1.814 1.812 1.81 1.808 1.806 1.806 1.804 1.804 2 2.5 3 3.5 4 2 4.5 3.5 4 4.5 5 5.5 VDDM Voltage (V) Buck2 Load Transient Response Buck2 Load Transient Response 6 @IOUT = 100mA to 400mA VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Load Current (200mA/Div) Output Voltage Deviation (100mV/Div) Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) 3 VDD2 Voltage (V) @IOUT = 100mA to 400mA Time (1ms/Div) VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) www.richtek.com 12 Output Voltage Deviation (100mV/Div) Buck2 Load Transient Response Load Current (200mA/Div) Output Voltage Deviation (100mV/Div) @IOUT = 100mA to 400mA VDD2 = 3V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) Buck2 Load Transient Response Load Current (200mA/Div) 2.5 @IOUT = 100mA to 400mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) DS9902-10 August 2007 RT9902 Preliminary Buck2 LX & Output Ripple Buck2 LX & Output Ripple @IOUT = 250mA Time (500ns/Div) Buck2 LX & Output Ripple Buck2 LX & Output Ripple LX2 (2V/Div) Output Ripple (10mV/Div) @IOUT = 250mA VDD2 = 3V, VDDM = 3.3V, VOUT = 1.8V @IOUT = 500mA VDD2 = 3V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) Buck2 LX & Output Ripple Buck2 LX & Output Ripple LX2 (2V/Div) @IOUT = 250mA VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) DS9902-10 August 2007 Output Ripple (10mV/Div) Output Ripple (10mV/Div) VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) LX2 (2V/Div) Output Ripple (10mV/Div) Output Ripple (10mV/Div) VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div) LX2 (2V/Div) LX2 (2V/Div) @IOUT = 500mA @IOUT = 500mA VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) www.richtek.com 13 RT9902 Preliminary Buck2 LX & Output Ripple Output Ripple (10mV/Div) Output Ripple (10mV/Div) LX2 (2V/Div) LX2 (2V/Div) Buck2 LX & Output Ripple @IOUT = 250mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V @IOUT = 500mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) Buck3 Efficiency vs. Output Current Buck3 Efficiency vs. Output Current 100 100 VOUT = 1.5V VOUT = 1.8V VIN = 2.2V 90 80 Efficiency (%) Efficiency (%) 90 VIN = 4.5V VIN = 3V VIN = 3.8V 70 VIN = 2.5V 80 VIN = 4.5V VIN = 3.8V VIN = 3V 70 60 60 50 50 1 10 100 1 1000 10 100 1000 Output Current (mA) Output Current (mA) Buck3 Output Voltage vs. VDD3 Voltage Buck3 Efficiency vs. Output Current 1.806 100 VBAT = VDDM = 3.3V, IOUT = 250mA VOUT = 2.5V 1.804 90 VIN = 4.5V Output Voltage (V) 80 Efficiency (%) VIN = 2.5V 70 VIN = 3.8V 60 50 VIN = 3V 40 1.802 1.8 1.798 1.796 1.794 1.792 1.79 30 1 10 100 Output Current (mA) www.richtek.com 14 1000 2 2.5 3 3.5 4 4.5 VDD3 Voltage (V) DS9902-10 August 2007 RT9902 Preliminary Buck3 Output Voltage vs. VDDM Voltage Buck3 Load Transient Response 1.806 Output Voltage Deviation (100mV/Div) VDD3 = 3.3V, IOUT = 250mA 1.802 1.8 @IOUT = 100mA to 400mA 1.798 1.796 Load Current (200mA/Div) Output Voltage (V) 1.804 1.794 1.792 1.79 2 2.5 3 3.5 4 4.5 5 5.5 VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V 6 Time (1ms/Div) VDDM Voltage (V) VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V Load Current (200mA/Div) Load Current (200mA/Div) Output Voltage Deviation (100mV/Div) @IOUT = 100mA to 400mA Buck3 Load Transient Response Output Voltage Deviation (100mV/Div) Buck3 Load Transient Response VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) Time (1ms/Div) Buck3 Load Transient Response Buck3 LX & Output Ripple @IOUT = 250mA VDD3 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) DS9902-10 August 2007 Output Ripple (10mV/Div) LX3 (2V/Div) Output Voltage Deviation (100mV/Div) @IOUT = 100mA to 400mA Load Current (200mA/Div) @IOUT = 100mA to 400mA VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) www.richtek.com 15 RT9902 Preliminary Buck3 LX & Output Ripple Buck3 LX & Output Ripple Output Ripple (10mV/Div) VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V LX3 Output Ripple (10mV/Div) (2V/Div) @IOUT = 250mA LX3 (2V/Div) @IOUT = 500mA Time (500ns/Div) Time (500ns/Div) Buck3 LX & Output Ripple Buck3 LX & Output Ripple @IOUT = 500mA @IOUT = 250mA VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V LX3 Output Ripple (10mV/Div) (2V/Div) LX3 Output Ripple (2V/Div) (10mV/Div) VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) Buck3 LX & Output Ripple Buck3 LX & Output Ripple VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) www.richtek.com 16 LX3 Output Ripple (10mV/Div) (2V/Div) Output Ripple (10mV/Div) LX3 (2V/Div) @IOUT = 500mA @IOUT = 250mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) DS9902-10 August 2007 RT9902 Preliminary Buck3 LX & Output Ripple Charge Pump CX & Output Ripple @IOUT = 1mA Output Ripple (10mV/Div) LX3 (2V/Div) Output Ripple Charge Pump (5mV/Div) (2V/Div) @IOUT = 500mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V VIN = 2V, VDDM = 3.3V, VOUT = 3.3V Time (500ns/Div) Time (5us/Div) Charge Pump CX & Output Ripple Linear Controller Load Transient Response Output Voltage Deviation (mV) Load Current (mA) Output Ripple Charge Pump (5mV/Div) (2V/Div) @IOUT = 1mA VIN = 2.5V, VDDM = 3.3V, VOUT = 3.3V VIN = 3.5V, VOUT = 3.3V 20 TA = 25°C 0 -20 400 200 0 Time (25us/Div) Time (1ms/Div) 0 -20 ≈ 400 200 0 Time (1ms/Div) DS9902-10 August 2007 Output Voltage Deviation (mV) VIN = 3.8V, VOUT = 3.3V 20 TA = 25°C Linear Controller Load Transient Response Load Current (mA) Load Current (mA) Output Voltage Deviation (mV) Linear Controller Load Transient Response ≈ ≈ ≈ VIN = 4.2V, VOUT = 3.3V 10 TA = 25°C 0 -10 ≈ ≈ 400 200 0 Time (1ms/Div) www.richtek.com 17 RT9902 Preliminary 0 -10 ≈ ≈ 400 Output Voltage Deviation (mV) VIN = 3.3V, VOUT = 3.3V 10 TA = 25°C Boost Series Linear Controller Load Transient Response Load Current (mA) Load Current (mA) Output Voltage Deviation (mV) Boost Series Linear Controller Load Transient Response 200 0 Time (1ms/Div) VIN = 3V, VOUT = 3.3V 10 TA = 25°C 0 -10 ≈ ≈ 400 200 0 Time (1ms/Div) Load Current (mA) Output Voltage Deviation (mV) Boost Series Linear Controller Load Transient Response VIN = 4.2V, VOUT = 3.3V 10 TA = 25°C 0 -10 ≈ ≈ 400 200 0 Time (1ms/Div) www.richtek.com 18 DS9902-10 August 2007 Preliminary RT9902 Application Information The RT9902 is a four-channel DC/DC converter with one linear controller for digital still cameras and other handheld device. The four channels DC/DC converters are as follows: CH1: Step-up, asynchronous current mode DC/DC converter with an internal power MOSFET, current limit protection and high efficiency control for wide loading range. CH2: Step-down, synchronous current mode DC/DC converter with internal power MOSFETs, current limit, short-circuit , over voltage protection and high efficiency control for wide loading range. CH3: Step-down, synchronous current mode DC/DC converter with internal power MOSFETs, current limit, short-circuit protection and high efficiency control for wide loading range. CH4: Charge pump DC/DC converter. Soft-Start CH1, CH2 and CH3 can be soft-started individually every time when the channel is enabled. Soft-start is achieved by ramping up the voltage reference of each channel's input of error amplifier. Adding a capacitor on SS pin to ground sets the ramping up speed of each voltage reference. Triangle wave will be appeared on SS pin, which provides a clock base for soft-start. The soft-start timing would be setted by following formular. TSS = 10 × CSS 1nF At light load, efficiency is enhanced by pulse-skipping mode. In this mode, the NMOS turns on by a constant pulse width. As loading increased, the converter operates at constant frequency PWM mode. The maximum duty of the constant frequency is 80% for the boost to prevent high input current drawn from input. Protection Current Limit The current of NMOS is sensed cycle by cycle to prevent over current. If the current is higher than 2.6A (typical), then the NMOS is off . This state is latched and then reset automatically at next clock cycle. Under Voltage The status of under voltage is decided by comparing FB1 voltage with 0.4V. This function is enabled after soft-start finishes. If the FB1 voltage is less than 0.4V, then the NMOS will be turned off immediately. And this state is latched. After a dummy count period, the controller begins a re-soft-start procedure. If the status of under voltage remains after 4 successive times of soft-start, then CH1 is latched. Over Voltage The over voltage protection is used when the output of CH1 supplies the power of the main chip. If the output voltage of CH1 is over 6.5V, the main chip is shutdown and the NMOS is kept off. (ms) Oscillator The internal oscillator synchronizes CH1, CH2 and CH3 PWM operation frequency. The operation frequency is set by a resistor between RT pin to ground, ranging from 550kHz to 1.4MHz. Step-up (Boost) DC/DC Converter (CH1) The step-up channel (CH1) is designed as current-mode DC/DC PWM converters with built-in internal power MOS and external schottky diode. Output voltage is regulated and adjustable up to 5.5V. This channel typically supplies 3.3V for main system power. DS9902-10 August 2007 Step-Down (Buck) DC/DC Converter (CH2, CH3) The step-down channels (CH2, CH3) are designed as synchronous current-mode DC/DC PWM converters. Output voltage is regulated and adjustable down to 0.8V. The internal synchronous power switches eliminate the typical schottky free wheeling diode and improve efficiency. At light load, efficiency is enhanced by pulse-skipping mode. In this mode, the high-side PMOS turns on by a constant pulse width. As loading increased, the converter operates at constant frequency PWM mode. 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. www.richtek.com 19 RT9902 Preliminary Protection Current Limit (CH2, CH3) The current of high-side PMOS is sensed cycle by cycle to prevent over current. If the current is higher than 1.5A (typical), then the high-side PMOS is off and the low-side NMOS is on. This state is latched and then reset automatically at next clock cycle. IMAX = 2 x (VDDC-VF) x CCP x FCP z VF : Schottky diode forward voltage z Fpump : Charge pump maximum frequency is 500kHz Recommand CCP ≤ 0.1μF. VBAT VDDC Under Voltage (CH2, CH3) The status of under voltage is decided by comparing FB2 (or FB3) voltage with 0.4V. This function is enabled after soft-start finishes. If the FB2 (or FB3) voltage is less than 0.4V, then the high/low-side power MOS are turned off immediately. And this state is latched. After a dummy count period, the CH2 (or CH3) begins a soft-start procedure. However, if the status of under voltage remains after 3 successive times of soft-start, then CH2 (or CH3) is latched. UV remain after 3 How to reset? successive soft-start CH2 CH2 is latched, and whole Toggle ENM IC is shut down CH3 CH3 is latched Toggle EN3 or ENM Over Voltage Protection (CH2) Over voltage protection (OVP) is used to protect the external parts connected to the output of CH2. If the FB2 voltage is higher than 1V, the high-side PMOS is off and low-side NMOS is on. This status is latched and could be reset by toggling ENM. CX CCP R1 CPFB GND R2 CX COUT Reference The chip has an internal 0.8V reference voltage, which is the inputs of the error amplifiers of the CH1, CH2, and CH3 to compare the difference of feedback voltage. The reference voltage can be set up stably when the supplied power (VDDM) is above 1.5V, and EN1 (or EN2, EN3) goes high. Thermal Protection Thermal protection function is integrated in the chip. When the chip temperature is higher than 178 °C, the controllers of CH1, CH2, and CH3 are shutdown. 10°C is the hysteresis range of temperature to prevent unstable operation when the thermal protection happens. When the thermal protection is relieved, the chip operates well again. Charge Pump DC/DC Converter This is a low quiescent charge pump DC/DC converter, which is enabled by ENM. Add a capacitor CX (~1nF) between charge pump VOUT and CPFB to speed up charge pump response time. Output ripple can be easily suppressed by increasing the capacitance ratio of COUT and CCP. This charge pump DC/DC converter can apply to μC stanby power or the gate driver power of IGBT for photoflash, etc. The maximum output current can be determined by CCP and C OUT ration. This equation would describe the relationship. www.richtek.com 20 DS9902-10 August 2007 RT9902 Preliminary Outline Dimension D2 D SEE DETAIL A L 1 E E2 e b 1 1 2 2 A A1 A3 DETAIL A Pin #1 ID and Tie Bar Mark Options 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 4.950 5.050 0.195 0.199 D2 3.400 3.750 0.134 0.148 E 4.950 5.050 0.195 0.199 E2 3.400 3.750 0.134 0.148 e L 0.500 0.350 0.020 0.450 0.014 0.018 V-Type 32L QFN 5x5 Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)89191466 Fax: (8862)89191465 Email: [email protected] DS9902-10 August 2007 www.richtek.com 21