RT9901

RT9901 RICHTEK | Alldatasheet

Document overview

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Technical content

Features

zzzzz 1.5V to 5.5V Battery Input Voltage Range zzzzz Main step-up DC-DC Converter \\\\\1.5V to 5.5V Adjustable Output Voltage \\\\\Up to 90% Efficiency \\\\\2.6A, 0.3Ω Ω Ω Ω Ω Internal Power Switch zzzzz Two Step-Down DC-DC Converters \\\\\0.8V to 5.5V Adjustable Output Voltage zzzzz Step-up Charge Pump for Micro-Controller zzzzz Build-in 0.8V Voltage Detector zzzzz Up to 1.4MHz Switching Frequency zzzzz 1μμμμμA Supply Current in Shutdown Mode zzzzz Programmable Soft Start Function zzzzz Independent Enable Pin (CH1, CH2, CH3) zzzzz External Compensation Network (CH1, CH2, CH3) zzzzz Short Circuit Protection (CH1, CH2, CH3) zzzzz Over Voltage Protection (CH2) zzzzz 32-Lead VQFN Package zzzzz RoHS Compliant and 100% Lead (Pb)-Free

Applications

4 Channel DC/DC Converters IC with High-Efficiency Step-Up

Ordering Information

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 high- efficiency 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. Pin Configurations (TOP VIEW) VQFN-32L 5x5 Note : Richtek Pb-free and Green products are : \RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. \Suitable for use in SnPb or Pb-free soldering processes. \`100% matte tin (Sn) plating. RT9901 Package Type QV : VQFN-32L 5x5 (V-Type) Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commer- cial Standard) COMP3 VDD3 LX3 PGND3 SS LBO RT GND VDD2 VDD2 LX2 LX2 PGND2 LX1 LX1 VDD1 PGND1 LBI VDDM FB1 COMP1 CPFB CX VDDC COMP2 ENM GND EN3 EN2 FB2 FB3 EN1 1615 91 0 1 1 1 2 1 4 13 28 27 26 25 32 31 30 29 GND

Figure 1. Typical Application Circuit from 1-cell Li+ Battery

Figure 2. Typical Application Circuit from 2-AA Battery Supply

DS9901-12 August 2007www.richtek.com Function Block Diagram EN Voltage Dector CH4 Charge Pump Soft-Start OSC PWM OSC CH1 Current-MODE Asynchronous Step-Up PWM Boost CH2 Current-MODE Synchronous Step-Down PWM Buck2 CH3 Current-MODE Synchronous Step-Down PWM Buck3 LBO LBI CX CPFB SS RT VDDM ENM GND GND VDD1 EN1 LX1 FB1 COMP1 PGND1 VDD2 EN2 LX2 FB2 COMP2 PGND2 VDD3 EN3 LX3 FB3 COMP3 PGND3 Thermal Shutdown ENVDDC ENM EN1 EN2 EN3 Charge CH1+Voltage CH2 CH3 Pump Detector

0 X X X Off Off Off Off

DS9901-12 August 2007 www.richtek.com Pin No. Pin Name Pin Function 1 COMP3 CH3 feedback compensation pin. 2 VDD3 CH3 power input pin. 3 LX3 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 Power ground for CH3. 5 SS Sets the soft start interval of the converter. Connect a capacitor from this pin to ground. 6 RT Frequency setting resistor connection pin. Frequency is 500KHz if RT pin not connected

7 GND Analog Ground

8 LBO Voltage detector output. 9 VDDM Device input power pin. 10 LBI Voltage detector 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. 18, 19 LX1 CH1 switch node. Connect an inductor to LX1 pins together as close as possible. 20 PGND2 Power ground for CH2. 21, 22 LX2 CH2 switch node. Drains of the internal P-channel and N-MOSFET switches. Connect an inductor to LX2 pins together as close as possible. 23, 24 VDD2 CH2 power input pin. 25 ENM Whole device control pin. Tie this pin higher than 1.3V to enable the device. Tie below 0.4V to turn off the device. 26 EN1 CH1 enable input. Tie this pin higher than 1.3V to enable CH1. Tie below 0.4V to turn off the CH1. 27 COMP2 CH2 feedback compensation pin. 28 FB2 CH2 feedback input. 29 EN2 CH2 enable input. Tie this pin higher than 1.3V to enable CH2. Tie below 0.4V to turn off the CH2. 30 EN3 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 The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Functional Pin Description

DS9901-12 August 2007www.richtek.com

Electrical Characteristics

(VDDM =3.3V, TA = 25°C, Unless Otherwise specification) To be continued Parameter Symbol Test Condition Min Typ Max Units Supply Voltage Minimum Startup Voltage (Boost) V ST Boost loading < 1mA -- 1.5 -- V VDDM Operating Voltage V VDDM VDDM Pin Voltage 2.4 -- 5.5 V VDD1, VDD2, VDD3 Operating Voltage VVDD1 VVDD2, VVDD3 VDD1, VDD2, VDD3 Pin Voltage 1.5 5.5 V VDDM Over Voltage Protection -- 6.5 -- V Supply Current Shutdown Supply Current I OFF V ENM pin=0V -- 0.01 1 μA Charge Pump Current I VDDM VVDDM = 3.3V, VENM = 3.3V, VEN1 = 0V, VEN2 = 0V, VEN3 = 0V -- 30 42 μA CH1 DC/DC Converter + Voltage Detector Supply Current IVDDM VVDDM = 3.3V, VFB1 = 0.9V VENM = 3.3V, VEN1 = 3.3V, VEN2 = 0V, VEN3 = 0V -- 250 350 μA CH2 DC/DC Converter Supply Current IVDDM VVDDM = 3.3V, VFB2 = 0.9V VENM = 3.3V, VEN1 = 0V, VEN2 = 3.3V, VEN3 = 0V -- 250 350 μA CH3 DC/DC Converter Supply Current IVDDM VVDDM = 3.3V, VFB3 = 0.9V VENM = 3.3V, VEN1 = 0V, VEN2 = 0V, VEN3 = 3.3V -- 250 350 μA Absolute Maximum Ratings z Package Thermal Resistance z ESD Susceptibility

DS9901-12 August 2007 www.richtek.com Parameter Symbol Test Condition Min Typ Max Units Oscillator Operation Frequency Range F OSC RT Open 475 550 625 kHz CH1 Maximum Duty Cycle D MAX1 -- 85 90 % CH2 Maximum Duty Cycle D MAX2 -- -- 100 % CH3 Maximum Duty Cycle D MAX3 -- -- 100 % Feedback Voltage (CH1, CH2, CH3, CH4) Feedback Voltage V FB CH1, CH2, CH3 0.788 0.8 0.812 V Feedback Voltage (Charge Pump) VCPFB CH4 0.78 0.8 0.82 V Feedback Voltage ︱ΔVFB︱ CH1, CH2, CH3, CH4 3.0V < VDDM < 5.5V -- -- 12 mV Error Amplifier GM -- 0.2 -- ms Compensation Source Current -- 22 -- μA Compensation Sink Current -- 22 -- μA Power Switch CH1 On Resistance of MOSFET R DS(ON) N-MOSFET -- 300 400 m Ω CH1 Current Limitation V VDD1 = 3.3V 2 2.6 3 A N-MOSFET, VVDD2 = 3.3V -- 350 450 m Ω CH2 On Resistance of MOSFET R DS(ON) P-MOSFET, VVDD2 = 3.3V -- 350 450 m Ω CH2 Current Limitation V VDD2 = 3.3V 1.3 1.5 1.9 A N-MOSFET, VVDD3 = 3.3V -- 350 450 m Ω CH3 On Resistance of MOSFET R DS(ON) P-MOSFET, VVDD3 = 3.3V -- 350 450 m Ω CH3 Current Limitation V VDD3 = 3.3V 1.3 1.5 1.9 A Voltage Detector Feedback Voltage for Voltage detector VLBI (Falling) 0.75 0.77 0.79 V Feedback Voltage for Voltage detector VLBI (Rising) 0.79 0.81 0.83 V LBO pin Sink Current V LBO= 1V 3 5 -- mA UVP (CH2, CH3) & Over Voltage Protection (CH2) UVP Threshold Voltage @FB2, FB3 0.3 0.4 0.5 V Over Voltage Protection @FB2 0.95 1 -- V Control ENM, EN1, EN2, EN3 Input High Level Threshold VVDDM = 3.3V -- 0.8 1.3 V ENM, EN1, EN2, EN3 Input Low Level Threshold VVDDM = 3.3V 0.4 0.8 -- V Thermal Protection Thermal Shutdown T SD 140 180 -- °C Thermal Shutdown Hysteresis ΔTSD -- 10 -- °C

DS9901-12 August 2007www.richtek.com Typical Operating Characteristics Oscillator Ferquency vs. RRT 200 400 600 800 1000 1200 1400 1600 1800 0 100 200 300 400 500 600 RRT (kΩ) Oscillator Frequecny (kHz) Boost Efficiency vs. Output Current 100 1 10 100 1000 Output Current (mA) Efficiency (%) VOUT = 3.3V VIN 2.5V 1.8V Boost Time (1ms/Div) Boost Load Transient Response VIN = 1.8V, VOUT = 3.3V, @IOUT = 100mA to 400mA Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) (°C) Reference Voltage vs. Temperature 0.792 0.794 0.796 0.798 0.8 0.802 0.804 0.806 0.808 - 5 0 - 3 0 - 1 0 1 03 05 07 09 0 Temperature Reference Voltage (V) Boost Output Voltage vs. VDDM Voltage 3.316 3.318 3.32 3.322 3.324 3.326 3.328 3.33 3.332 VDDM Voltage (V) Output Voltage (V) VBAT = 2.5V, VDD1 = 3.3V, IOUT = 250mA Boost Output Voltage vs. VDD1 Voltage 3.305 3.31 3.315 3.32 3.325 3.33 3.335 3.34 3.345 VDD1 Voltage (V) Output Voltage (V) VBAT = 2.5V, VDDM = 3.3V, IOUT = 250mA

DS9901-12 August 2007 www.richtek.com Time (1ms/Div) Boost Load Transient Response VIN = 2.5V, VOUT = 3.3V, @IOUT = 100mA to 400mA Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) Time (1ms/Div) Boost Load Transient Response VIN = 2V, VOUT = 3.3V, @IOUT = 100mA to 400mA Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) Boost LX & Output Ripple Time (1us/Div) VIN = 1.8V, VOUT = 3.3V, @IOUT = 100mA LX1 (2V/Div) Output Ripple (10mV/Div) Boost LX & Output Ripple Time (1us/Div) VIN = 2.5V, VOUT = 3.3V, @IOUT = 100mA LX1 (2V/Div) Output Ripple (10mV/Div) Boost LX & Output Ripple Time (1us/Div) VIN = 1.8V, VOUT = 3.3V, @IOUT = 300mA LX1 (2V/Div) Output Ripple (10mV/Div) Time (1ms/Div) Boost Load Transient Response VIN = 3V, VOUT = 3.3V, @IOUT = 100mA to 400mA Output Voltage Deviation (100mV/Div) Load Current (200mA/Div)

DS9901-12 August 2007www.richtek.com Buck2 Efficiency vs. Output Current 100 1 10 100 1000 Output Current (mA) Efficiency (%) VOUT = 2.5V VIN = 4.5 VIN = 3.8V VIN = 3V Buck2 Efficiency vs. Output Current 100 1 10 100 1000 Output Current (mA) Efficiency (%) VIN = 4.5V VIN = 3.8V VIN = 3V VIN = 2.5V VIN = 2.2V VOUT = 1.5V Buck2 Efficiency vs. Output Current 100 1 10 100 1000 Output Current (mA) Efficiency (%) VOUT = 1.8V VIN = 4.5 VIN = 3.8V VIN = 3V VIN = 2.5V Boost LX & Output Ripple Time (1us/Div) VIN = 2.5V, VOUT = 3.3V, @IOUT = 400mA LX1 (2V/Div) Output Ripple (10mV/Div) Boost LX & Output Ripple Time (1us/Div) VIN = 3V, VOUT = 3.3V, @IOUT = 100mA LX1 (2V/Div) Output Ripple (10mV/Div) Boost LX & Output Ripple Time (1us/Div) VIN = 3V, VOUT = 3.3V, @IOUT = 400mA LX1 (2V/Div) Output Ripple (10mV/Div)

DS9901-12 August 2007 www.richtek.com Time (1ms/Div) Buck2 Load Transient Response VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA Time (1ms/Div) Buck2 Load Transient Response VDD2 = 3V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA Time (1ms/Div) Buck2 Load Transient Response VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA Time (1ms/Div) Buck2 Load Transient Response VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA Buck2 Output Voltage vs. VDD2 Voltage 1.804 1.806 1.808 1.81 1.812 1.814 1.816 1.818 1.82 2 2.5 3 3.5 4 4.5 VDD2 Voltage (V) Output Voltage (V) VBAT = VDDM = 3.3V, IOUT = 250mA Buck2 Output Voltage vs. VDDM Voltage 1.804 1.806 1.808 1.81 1.812 1.814 1.816 1.818 1.82 2 2.5 3 3.5 4 4.5 5 5.5 6 VDDM Voltage (V) Output Voltage (V) VDD2 = 3.3V, IOUT = 250mA

DS9901-12 August 2007www.richtek.com Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div) @IOUT = 250mA Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 2.5V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div) @IOUT = 500mA Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 3V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div)@IOUT = 250mA Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 3V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div)@IOUT = 500mA Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div)@IOUT = 250mA Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 3.8V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div)@IOUT = 500mA

DS9901-12 August 2007 www.richtek.com Buck3 Efficiency vs. Output Current 100 1 10 100 1000 Output Current (mA) Efficiency (%) VOUT = 1.8V VIN = 4.5V VIN = 3.8V VIN = 3V VIN = 2.5V Buck3 Efficiency vs. Output Current 100 1 10 100 1000 Output Current (mA) Efficiency (%) VOUT = 2.5V VIN = 4.5V VIN = 3.8V VIN = 3V Buck3 Efficiency vs. Output Current 100 1 10 100 1000 Output Current (mA) Efficiency (%) VOUT = 1.5V VIN = 4.5V VIN = 3.8V VIN = 3V VIN = 2.5V VIN = 2.2V Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div)@IOUT = 500mA Buck2 LX & Output Ripple Time (500ns/Div) VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V LX2 (2V/Div) Output Ripple (10mV/Div)@IOUT = 250mA Buck3 Output Voltage vs. VDD3 Voltage 1.79 1.792 1.794 1.796 1.798 1.8 1.802 1.804 1.806 2 2.5 3 3.5 4 4.5 VDD3 Voltage (V) Output Voltage (V) VBAT = VDDM = 3.3V, IOUT = 250mA

DS9901-12 August 2007www.richtek.com Buck3 Output Voltage vs. VDDM Voltage 1.79 1.792 1.794 1.796 1.798 1.8 1.802 1.804 1.806 2 2.5 3 3.5 4 4.5 5 5.5 6 VDDM Voltage (V) Output Voltage (V) VDD3 = 3.3V, IOUT = 250mA Time (1ms/Div) Buck3 Load Transient Response VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA Time (1ms/Div) Buck3 Load Transient Response VDD3 = 4.5V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA Buck3 LX & Output Ripple Time (500ns/Div) VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V @IOUT = 250mA LX3 (2V/Div) Output Ripple (10mV/Div) Time (1ms/Div) Buck3 Load Transient Response VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA Time (1ms/Div) Buck3 Load Transient Response VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V Output Voltage Deviation (100mV/Div) Load Current (200mA/Div) @IOUT = 100mA to 400mA

DS9901-12 August 2007 www.richtek.com Buck3 LX & Output Ripple Time (500ns/Div) VDD3 = 2.5V, VDDM = 3.3V, VOUT = 1.8V LX3 (2V/Div) Output Ripple (10mV/Div) @IOUT = 500mA Buck3 LX & Output Ripple Time (500ns/Div) VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V LX3 (2V/Div) Output Ripple (10mV/Div) @IOUT = 500mA Buck3 LX & Output Ripple Time (500ns/Div) VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V LX3 (2V/Div) Output Ripple (10mV/Div) @IOUT = 500mA Buck3 LX & Output Ripple Time (500ns/Div) VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V LX3 (2V/Div) Output Ripple (10mV/Div)@IOUT = 250mA Buck3 LX & Output Ripple Time (500ns/Div) VDD3 = 3.8V, VDDM = 3.3V, VOUT = 1.8V LX3 (2V/Div) Output Ripple (10mV/Div) @IOUT = 250mA Buck3 LX & Output Ripple Time (500ns/Div) VDD3 = 3V, VDDM = 3.3V, VOUT = 1.8V LX3 (2V/Div) Output Ripple (10mV/Div) @IOUT = 250mA

DS9901-12 August 2007www.richtek.com Buck3 LX & Output Ripple Time (500ns/Div) VDD2 = 4.5V, VDDM = 3.3V, VOUT = 1.8V LX3 (2V/Div) Output Ripple (10mV/Div) @IOUT = 500mA Charge Pump CX & Output Ripple Time (25us/Div) VIN = 2.5V, VDDM = 3.3V, VOUT = 3.3V Output Ripple (5mV/Div) @IOUT = 1mA Charge Pump (2V/Div) Charge Pump CX & Output Ripple Time (5us/Div) VIN = 2V, VDDM = 3.3V, VOUT = 3.3V Output Ripple (5mV/Div) @IOUT = 1mA Charge Pump (2V/Div)

DS9901-12 August 2007 www.richtek.com

Application Information

The RT9901 is a four-channel DC/DC converter with one voltage detector for digital still cameras and other hand- held 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. 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. 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 remain s 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 (ms) 1nF C x 10 T SS SS =

DS9901-12 August 2007www.richtek.com 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 successive soft-start How to reset? CH2 CH2 is latched, and whole IC is shut down Toggle ENM 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. Charge Pump DC/DC converter This is a low quiescent charge pump DC/DC converter, which is enabled by ENM. Add a capacitor C X (~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 C OUT and Cpump. 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 Cpump and C OUT ration. This equation would describe the relationship. IMAX = 2 x (VDDC-VF) x Cpump x Fpump z VF : Schottky diode forward voltage z Fpump : Charge pump maximum frequency is 500kHz Recommand Cpump ≤ 0.1μF. 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. VDDC CX CPFB GND VBAT Cpump COUT CXR1

DS9901-12 August 2007 www.richtek.com 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 Outline Dimension E D L be A SEE DETAIL A Dimensions In Millimeters Dimensions In Inches Symbol 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 0.500 0.020 L 0.350 0.450 0.014 0.018 V-Type 32L QFN 5x5 Package Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. DETAIL A Pin #1 ID and Tie Bar Mark Options 2 2