RT9901GQV

Preliminary RT9901 4 Channel DC/DC Converters IC with High-Efficiency Step-Up and Step-Down General Description The RT9901 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 voltage detector. The RT9901 is targeted for applications that use either two or three AA cells or a single lithiumion battery. 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 converters have independent shutdown inputs. The feature of the charge pump is to deliver few current to micro-controller when the system operates in the standby mode. RT9901 include a low battery detector with 0.8V detection voltage. An adjustable operating frequency (up to 1.4MHZ) is utilized to get optimum size, cost, and efficiency. RT9901 is available in VQFN-32L 5x5 package. Features 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 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 Build-in 0.8V Voltage Detector Up to 1.4MHz Switching Frequency 1μA 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 Applications Digital Still Camera PDAs Portable Device Ordering Information RT9901 Package Type QV : VQFN-32L 5x5 (V-Type) Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard) Pin Configurations (TOP VIEW) COMP2 GND ENM 24 23 22 EN3 EN2 Note : Richtek Pb-free and Green products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. 100% matte tin (Sn) plating. COMP3 VDD3 LX3 PGND3 SS RT GND LBO 1 2 3 4 5 6 7 8 32 31 30 29 28 27 EN1 FB3 FB2 26 25 VDD2 VDD2 LX2 LX2 PGND2 LX1 LX1 VDD1 GND 21 20 19 33 18 17 9 10 11 12 13 14 15 16 FB1 COMP1 VQFN-32L 5x5 DS9901-12 August 2007 www.richtek.com 1 PGND1 CPFB VDDM VDDC LBI CX RT9901 Typical Application Circuit 1-cell Li+ Battery 3.4V to 4.2V Preliminary V BAT 1μF 9 V BAT 1.5V/500mA C17 to C20 10 μ F x 4 R1 200k R2 220k C3 100pF V BAT C4 10 μ F IGBT Driver 5V/50mA C7 to C8 10 μ F x 2 R3 680k C5 1nF R4 130k Chip Enable D2 SS0520 D1 SS0520 C6 C1 to C2 10 μ F x 2 VDDM 2 VDD3 L1 4.7 μ H 3 LX3 32 14 C13 C14 10 μ F 10 μ F L2 4 .7 μ H C15 0.1 μ F 3 4 Chip Enable D3 SS0520 LX1 18 19 17 5V/500mA RT9701CB 5 VIN VOUT EN VOUT 1 GND 2 10uF FB3 VDDC VDD1 11 FB1 RT9901 LBO LBI 8 10 R9 680k R10 130k C16 100pF C21 to C24 10 μ F x 4 15 CX CPFB 22nF 13 25 ENM 26 EN1 29 30 EN2 EN3 R11 R12 Low Battery Warning Output (Open Drain) 23 VDD2 24 L3 4.7 μ H C23 100pF FB2 PGND3 PGND2 PGND1 GND 28 V BAT C25 to C26 10 μ F x 2 3.3V/500mA R5 20k R6 30k C9 4.7nF C10 1nF C11 1nF C12 1nF R7 30k 12 COMP1 27 COMP2 1 COMP3 5 SS RT LX2 21 22 R13 470k C27 to C30 10 μ F x 4 R14 150k 6 R8 4 20 16 7, 31, Exposed Pad (33) Figure 1. Typical Application Circuit from 1-cell Li+ Battery www.richtek.com 2 DS9901-12 August 2007 Preliminary 2-AA Battery 2.0V to 3.4V RT9901 C12 1μ F 9 V BAT 1.5V/300mA C27 to C30 10 μ F x 4 R1 200k R2 220k C3 100pF V BAT C4 10 μ F μ C standby 3.3V/1mA C7 10 μ F C6 R3 47k R4 15k Chip Enable D2 C5 SS0520 10nF 1nF 15 13 D1 SS0520 C1 to C2 10 μ F x 2 VDD3 VDDM 2 L1 4.7 μ H L2 4.7 μ H D3 SS0520 V BAT C15 to C16 10 μ F x 2 I/O 3.3V/500mA C17 to C20 10 μ F x 4 Low Battery Warning Output (Open Drain) V BAT 3 LX3 32 FB3 14 VDDC LX1 18 19 17 VDD1 FB1 CX CPFB RT9901 LBO LBI 11 R9 470k R10 150k C13 100pF 8 10 R12 R11 25 ENM 26 EN1 29 30 EN2 EN3 COMP1 COMP2 23 VDD2 24 L3 4.7 μ H C14 100pF FB2 PGND3 PGND2 PGND1 GND 28 3.3V C21 to C22 10 μ F x 2 2.5V/300mA R13 470k C23 to C26 10 μ F x 4 R14 220k R5 20k R6 30k C9 1nF C10 1nF C11 1nF R7 30k 12 27 21 LX2 22 C8 4.7nF 1 COMP3 5 SS RT 6 R8 4 20 16 7, 31, Exposed Pad (33) Figure 2. Typical Application Circuit from 2-AA Battery Supply DS9901-12 August 2007 www.richtek.com 3 RT9901 Function Block Diagram Preliminary VDDM ENM VDDC CX CPFB LBO CH4 Charge Pump EN CH1 Current-MODE Asynchronous Step-Up PWM Boost EN1 VDD1 LX1 PGND1 COMP1 FB1 EN2 VDD2 LX2 PGND2 COMP2 FB2 EN3 VDD3 LX3 PGND3 COMP3 FB3 EN Voltage Dector LBI SS Soft-Start OSC CH2 Current-MODE Synchronous Step-Down PWM Buck2 RT PWM OSC Thermal Shutdown CH3 Current-MODE Synchronous Step-Down PWM Buck3 GND GND ENM EN1 EN2 EN3 Charge Pump CH1+Voltage Detector Off Off On On On CH2 CH3 0 1 1 1 1 X 0 1 1 1 X 0 0 1 1 X 0 0 0 1 Off On On On On Off Off Off On On Off Off Off Off On www.richtek.com 4 DS9901-12 August 2007 Preliminary Functional Pin Description Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18, 19 20 21, 22 23, 24 25 26 27 28 29 30 31 32 Pin Name COMP3 VDD3 LX3 PGND3 SS RT GND LBO VDDM LBI FB1 COMP1 CPFB VDDC CX PGND1 VDD1 LX1 PGND2 LX2 VDD2 ENM EN1 COMP2 FB2 EN2 EN3 GND FB3 CH3 feedback compensation pin. Pin Function RT9901 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. 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 Analog Ground Voltage detector output. Device input power pin. Voltage detector feedback input. CH1 feedback input pin. CH1 feedback compensation pin. Charge pump feedback pin. Charge pump power input pin. Charge pump external driver pin. Power ground for CH1. CH1 power input pin. Connect output of Boost to this pin. CH1 switch node. Connect an inductor to LX1 pins together as close as possible. Power ground for CH2. CH2 switch node. Drains of the internal P-channel and N-MOSFET switches. Connect an inductor to LX2 pins together as close as possible. 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. CH2 feedback compensation pin. 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. Analog ground. CH3 feedback input. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Exposed Pad (33) GND DS9901-12 August 2007 www.richtek.com 5 RT9901 Absolute Maximum Ratings Preliminary 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 Supply Voltage Minimum Startup Voltage (Boost) VDDM Operating Voltage VDD1, VDD2, VDD3 Operating Voltage VDDM Over Voltage Protection Supply Current Shutdown Supply Current Charge Pump Current Symbol VST VVDDM VVDD1 VVDD2, VVDD3 Test Condition Boost loading < 1mA VDDM Pin Voltage VDD1, VDD2, VDD3 Pin Voltage Min -2.4 1.5 -- Typ 1.5 -- Max -5.5 5.5 Units V V V V μA μA 6.5 0.01 30 -1 42 IOFF IVDDM VENM pin=0V VVDDM = 3.3V, VENM = 3.3V, VEN1 = 0V, VEN2 = 0V, VEN3 = 0V VVDDM = 3.3V, --- CH1 DC/DC Converter + Voltage Detector Supply Current IVDDM VFB1 = 0.9V VENM = 3.3V, VEN1 = 3.3V, VEN2 = 0V, VEN3 = 0V VVDDM = 3.3V, -- 250 350 μA CH2 DC/DC Converter Supply Current IVDDM VFB2 = 0.9V VENM = 3.3V, VEN1 = 0V, VEN2 = 3.3V, VEN3 = 0V VVDDM = 3.3V, -- 250 350 μA CH3 DC/DC Converter Supply Current IVDDM VFB3 = 0.9V VENM = 3.3V, VEN1 = 0V, VEN2 = 0V, VEN3 = 3.3V -- 250 350 μA To be continued www.richtek.com 6 DS9901-12 August 2007 Preliminary Parameter Oscillator Operation Frequency Range CH1 Maximum Duty Cycle CH2 Maximum Duty Cycle CH3 Maximum Duty Cycle Feedback Voltage Feedback Voltage (Charge Pump) Feedback Voltage Error Amplifier GM Compensation Source Current Compensation Sink Current Power Switch CH1 On Resistance of MOSFET CH1 Current Limitation CH2 On Resistance of MOSFET CH2 Current Limitation CH3 On Resistance of MOSFET CH3 Current Limitation Voltage Detector Feedback Voltage for Voltage detector Feedback Voltage for Voltage detector LBO pin Sink Current UVP Threshold Voltage @FB2, FB3 Over Voltage Protection @FB2 Control ENM, EN1, EN2, EN3 Input High Level Threshold ENM, EN1, EN2, EN3 Input Low Level Threshold Thermal Protection Thermal Shutdown Thermal Shutdown Hysteresis TSD ΔTSD VVDDM = 3.3V VVDDM = 3.3V VLBI (Falling) VLBI (Rising) VLBO= 1V 0.75 0.79 3 0.3 0.95 -0.4 0.77 0.81 5 0.4 1 0.8 0.8 RDS(ON) RDS(ON) RDS(ON) N-MOSFET VVDD1 = 3.3V N-MOSFET, VVDD2 = 3.3V P-MOSFET, VVDD2 = 3.3V VVDD2 = 3.3V N-MOSFET, VVDD3 = 3.3V P-MOSFET, VVDD3 = 3.3V VVDD3 = 3.3V -2 --1.3 --1.3 300 2.6 350 350 1.5 350 350 1.5 ---0.2 22 22 FOSC DMAX1 DMAX2 DMAX3 VFB VCPFB ︱ΔVFB︱ CH1, CH2, CH3 CH4 CH1, CH2, CH3, CH4 3.0V < VDDM < 5.5V RT Open 475 ---0.788 0.78 -550 85 --0.8 0.8 -Symbol Test Condition Min Typ RT9901 Max 625 90 100 100 0.812 0.82 12 Units kHz % % % V V mV Feedback Voltage (CH1, CH2, CH3, CH4) ---400 3 450 450 1.9 450 450 1.9 ms μA μA mΩ A mΩ mΩ A mΩ mΩ A 0.79 0.83 -0.5 -1.3 -- V V mA V V V V °C °C UVP (CH2, CH3) & Over Voltage Protection (CH2) 140 -- 180 10 --- DS9901-12 August 2007 www.richtek.com 7 RT9901 Preliminary Typical Operating Characteristics Reference Voltage vs. Temperature 0.808 Oscillator Ferquency vs. RRT 1800 Oscillator Frequecny (kHz) -50 -30 -10 10 30 50 70 90 0.806 1600 1400 1200 1000 800 600 400 200 0 0 100 200 300 400 500 600 Reference Voltage (V) 0.804 0.802 0.8 0.798 0.796 0.794 0.792 Temperature (°C) RRT (kΩ) Boost Efficiency vs. Output Current 100 Boost Output Voltage vs. VDD1 Voltage 3.345 VOUT = 3.3V 90 VBAT = 2.5V, VDDM = 3.3V, IOUT = 250mA VIN 3V 2.5V 3.34 3.335 3.33 3.325 3.32 3.315 3.31 80 2V 1.8V 70 60 Boost 50 1 10 100 1000 Output Voltage (V) Efficiency (%) 3.305 1.5 2 2.5 3 3.5 4 4.5 5 5.5 Output Current (mA) VDD1 Voltage (V) Boost Output Voltage vs. VDDM Voltage 3.332 3.33 Boost Load Transient Response Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) VIN = 1.8V, VOUT = 3.3V, @IOUT = 100mA to 400mA VBAT = 2.5V, VDD1 = 3.3V, IOUT = 250mA Output Voltage (V) 3.328 3.326 3.324 3.322 3.32 3.318 3.316 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 Time (1ms/Div) VDDM Voltage (V) www.richtek.com 8 DS9901-12 August 2007 Preliminary RT9901 Boost Load Transient Response Boost Load Transient Response Output Voltage Deviation (100mV/Div) Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) VIN = 2V, VOUT = 3.3V, @IOUT = 100mA to 400mA Load Current (200mA/Div) VIN = 2.5V, VOUT = 3.3V, @IOUT = 100mA to 400mA Time (1ms/Div) Time (1ms/Div) Boost Load Transient Response Output Voltage Deviation (100mV/Div) Boost LX & Output Ripple VIN = 1.8V, VOUT = 3.3V, @IOUT = 100mA Load Current (200mA/Div) VIN = 3V, VOUT = 3.3V, @IOUT = 100mA to 400mA Time (1ms/Div) Output Ripple (10mV/Div) LX1 (2V/Div) Time (1us/Div) Boost LX & Output Ripple VIN = 1.8V, VOUT = 3.3V, @IOUT = 300mA Boost LX & Output Ripple VIN = 2.5V, VOUT = 3.3V, @IOUT = 100mA LX1 (2V/Div) Output Ripple (10mV/Div) Time (1us/Div) Output Ripple (10mV/Div) LX1 (2V/Div) Time (1us/Div) DS9901-12 August 2007 www.richtek.com 9 RT9901 Boost LX & Output Ripple VIN = 2.5V, VOUT = 3.3V, @IOUT = 400mA Preliminary Boost LX & Output Ripple VIN = 3V, VOUT = 3.3V, @IOUT = 100mA LX1 (2V/Div) Output Ripple (10mV/Div) Time (1us/Div) Output Ripple (10mV/Div) LX1 (2V/Div) Time (1us/Div) Boost LX & Output Ripple VIN = 3V, VOUT = 3.3V, @IOUT = 400mA Buck2 Efficiency vs. Output Current 100 VOUT = 1.5V VIN = 2.2V 90 Efficiency (%) LX1 (2V/Div) 80 VIN = 4.5V 70 VIN = 2.5V Output Ripple (10mV/Div) VIN = 3V VIN = 3.8V 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 VOUT = 2.5V VIN = 4.5 90 90 80 Efficiency (%) 80 VIN = 4.5 VIN = 3.8V VIN = 3V Efficiency (%) 70 60 50 70 VIN = 3.8V VIN = 3V 60 40 30 50 1 10 100 1000 1 10 100 1000 Output Current (mA) Output Current (mA) www.richtek.com 10 DS9901-12 August 2007 Preliminary RT9901 Buck2 Output Voltage vs. VDDM Voltage 1.82 Buck2 Output Voltage vs. VDD2 Voltage 1.82 VBAT = VDDM = 3.3V, IOUT = 250mA 1.818 1.818 VDD2 = 3.3V, IOUT = 250mA Output Voltage (V) Output Voltage (V) 1.816 1.814 1.812 1.81 1.808 1.806 1.804 2 2.5 3 3.5 4 4.5 1.816 1.814 1.812 1.81 1.808 1.806 1.804 2 2.5 3 3.5 4 4.5 5 5.5 6 VDD2 Voltage (V) VDDM Voltage (V) Buck2 Load Transient Response @IOUT = 100mA to 400mA Buck2 Load Transient Response @IOUT = 100mA to 400mA Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Load Current (200mA/Div) Output Voltage Deviation (100mV/Div) VDD2 = 3V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) Time (1ms/Div) Buck2 Load Transient Response Output Voltage Deviation (100mV/Div) Output Voltage Deviation (100mV/Div) @IOUT = 100mA to 400mA Buck2 Load Transient Response @IOUT = 100mA to 400mA Load Current (200mA/Div) VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Load Current (200mA/Div) VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) Time (1ms/Div) DS9901-12 August 2007 www.richtek.com 11 RT9901 Buck2 LX & Output Ripple @IOUT = 500mA Preliminary Buck2 LX & Output Ripple @IOUT = 250mA LX2 (2V/Div) Output Ripple (10mV/Div) Output Ripple (10mV/Div) LX2 (2V/Div) VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) 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 Output Ripple (10mV/Div) LX2 (2V/Div) @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) Output Ripple (10mV/Div) @IOUT = 250mA VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Output Ripple (10mV/Div) LX2 (2V/Div) @IOUT = 500mA VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) www.richtek.com 12 DS9901-12 August 2007 Preliminary RT9901 Buck2 LX & Output Ripple Buck2 LX & Output Ripple LX2 (2V/Div) Output Ripple (10mV/Div) @IOUT = 250mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Output Ripple (10mV/Div) LX2 (2V/Div) @IOUT = 500mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) Buck3 Efficiency vs. Output Current 100 Buck3 Efficiency vs. Output Current 100 VOUT = 1.5V VIN = 2.2V 90 VOUT = 1.8V VIN = 2.5V 90 Efficiency (%) Efficiency (%) 80 VIN = 4.5V VIN = 3V VIN = 3.8V VIN = 2.5V 80 VIN = 4.5V VIN = 3.8V VIN = 3V 70 70 60 60 50 1 10 100 1000 50 1 10 100 1000 Output Current (mA) Output Current (mA) Buck3 Efficiency vs. Output Current 100 Buck3 Output Voltage vs. VDD3 Voltage 1.806 VOUT = 2.5V 90 VBAT = VDDM = 3.3V, IOUT = 250mA 1.804 VIN = 4.5V Output Voltage (V) 100 1000 80 1.802 1.8 1.798 1.796 1.794 1.792 1.79 Efficiency (%) 70 VIN = 3.8V 60 50 40 30 1 10 VIN = 3V 2 2.5 3 3.5 4 4.5 Output Current (mA) VDD3 Voltage (V) DS9901-12 August 2007 www.richtek.com 13 RT9901 Preliminary Buck3 Output Voltage vs. VDDM Voltage 1.806 1.804 Buck3 Load Transient Response Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA VDD3 = 3.3V, IOUT = 250mA 1.802 1.8 1.798 1.796 1.794 1.792 1.79 2 2.5 3 3.5 4 4.5 5 5.5 6 Output Voltage (V) VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) VDDM Voltage (V) Buck3 Load Transient Response Output Voltage Deviation (100mV/Div) Output Voltage Deviation (100mV/Div) @IOUT = 100mA to 400mA Buck3 Load Transient Response @IOUT = 100mA to 400mA Load Current (200mA/Div) VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V Load Current (200mA/Div) VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) Time (1ms/Div) Buck3 Load Transient Response @IOUT = 100mA to 400mA Buck3 LX & Output Ripple @IOUT = 250mA Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) VDD3 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Output Ripple (10mV/Div) LX3 (2V/Div) VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Time (1ms/Div) Time (500ns/Div) www.richtek.com 14 DS9901-12 August 2007 Preliminary RT9901 Buck3 LX & Output Ripple @IOUT = 250mA Buck3 LX & Output Ripple @IOUT = 500mA LX3 (2V/Div) Output Ripple (10mV/Div) VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V LX3 Output Ripple (10mV/Div) (2V/Div) VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) Buck3 LX & Output Ripple @IOUT = 500mA Buck3 LX & Output Ripple @IOUT = 250mA LX3 Output Ripple (10mV/Div) (2V/Div) VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V LX3 Output Ripple (10mV/Div) (2V/Div) VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) Buck3 LX & Output Ripple @IOUT = 500mA Buck3 LX & Output Ripple LX3 (2V/Div) Output Ripple (10mV/Div) LX3 Output Ripple (10mV/Div) (2V/Div) VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V @IOUT = 250mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Time (500ns/Div) Time (500ns/Div) DS9901-12 August 2007 www.richtek.com 15 RT9901 Buck3 LX & Output Ripple @IOUT = 500mA Preliminary Charge Pump CX & Output Ripple @IOUT = 1mA VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Output Ripple Charge Pump (5mV/Div) (2V/Div) Output Ripple (10mV/Div) LX3 (2V/Div) VIN = 2V, VDDM = 3.3V, VOUT = 3.3V Time (500ns/Div) Time (5us/Div) Charge Pump CX & Output Ripple @IOUT = 1mA Output Ripple Charge Pump (5mV/Div) (2V/Div) VIN = 2.5V, VDDM = 3.3V, VOUT = 3.3V Time (25us/Div) www.richtek.com 16 DS9901-12 August 2007 Preliminary Application Information The RT9901 is a four-channel DC/DC converter with one voltage detector 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 x 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. CSS (ms) 1nF RT9901 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 max. 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. 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 DS9901-12 August 2007 www.richtek.com 17 RT9901 Preliminary The maximum output current can be determined by Cpump and C OUT ration. This equation would describe the relationship. IMAX = 2 x (VDDC-VF) x Cpump x Fpump VF : Schottky diode forward voltage Fpump : Charge pump maximum frequency is 500kHz Recommand Cpump ≤ 0.1μF. enters low dropout mode. Duty could be as long as 100% to extend battery life. 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. 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 VDDC CX CPFB GND VBAT Cpump R1 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 degree C, the controllers of CH1, CH2, and CH3 are shutdown. 10 degree 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. 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. 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 Cpump. This charge pump DC/DC converter can apply to μC stanby power or the gate driver power of IGBT for photoflash, etc. www.richtek.com 18 DS9901-12 August 2007 Preliminary Outline Dimension RT9901 D D2 SEE DETAIL A L 1 E E2 e b 1 2 1 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 A A1 A3 b D D2 E E2 e L Dimensions In Millimeters Min 0.800 0.000 0.175 0.180 4.950 3.400 4.950 3.400 0.500 0.350 0.450 Max 1.000 0.050 0.250 0.300 5.050 3.750 5.050 3.750 Dimensions In Inches Min 0.031 0.000 0.007 0.007 0.195 0.134 0.195 0.134 0.020 0.014 0.018 Max 0.039 0.002 0.010 0.012 0.199 0.148 0.199 0.148 V-Type 32L QFN 5x5 Package Richtek Technology Corporation Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Richtek Technology Corporation Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com DS9901-12 August 2007 www.richtek.com 19