Kingbor Technology Co.,Ltd KB3408 TEL:(86)0755-26508846 FAX:(86)0755-26509052 1.5MHz, 350mA Synchronous Step-Down Regulator in SOT23-5 DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ High Efficiency: Up to 96% Very Low Quiescent Current: Only 20µA During Operation 350mA Output Current 2.5V to 7.4V Input Voltage Range 1.5MHz Constant Frequency Operation No Schottky Diode Required Low Dropout Operation: 100% Duty Cycle 0.6V Reference Allows Low Output Voltages Shutdown Mode Draws ) 1µA Supply Current Current Mode Operation for Excellent Line and Load Transient Response Overtemperature Protected Low Profile (1mm) SOT23-5 Package The KB3408 is a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. The device is available in an adjustable version and fixed output voltages of 1.8V and 3.3V. Supply current during operation is only 20µA and drops to )1µA in shutdown. The 2.5V to 7.4V input voltage range makes the KB3408 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. Automatic Burst Mode operation increases efficiency at light loads, further extending battery life. Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. The KB3408 is available in a low profile (1mm) SOT23-5 package. APPLICATIONS ■ ■ ■ ■ ■ ■ Cellular Telephones Personal Information Appliances Wireless and DSL Modems Digital Still Cameras MP3 Players Portable Instruments TYPICAL APPLICATION 95 90 4 + CIN 4.7µF Tan SW VIN 3 COUT 10µF CER KB3408-1.8 1 RUN VOUT 4.7µH VOUT 1.8V 350mA 5 85 EFFICIENCY (%) VIN 2.7V TO 7.4V VIN = 3.6V 80 VIN = 4.2V 75 70 GND 2 65 60 0.1 Figure 1a. High Efficiency Step-Down Converter March 2007 VIN = 2.7V VOUT = 1.8V 1 10 100 OUTPUT CURRENT (mA) 500 Figure 1b. Efficiency vs Load Current 1 KB3408 Kingbor Technology Co.,Ltd KB3408 TEL:(86)0755-26508846 FAX:(86)0755-26509052 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage .................................. – 0.3V to 7.5V RUN, VFB Voltages ..................................... – 0.3V to VIN SW Voltage .................................. – 0.3V to (VIN + 0.3V) P-Channel Switch Source Current (DC) ............. 400mA N-Channel Switch Sink Current (DC) ................. 400mA Peak SW Sink and Source Current .................... 350mA Operating Temperature Range (Note 2) .. – 40°C to 85°C Junction Temperature (Note 3) ............................ 125°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C PACkAGE/ORDER INFORMATION ORDER PART NUMBER TOP VIEW SW 3 5 VFB 4 VIN S5 PACKAGE 5-LEAD PLASTIC TSOT-23 TJMAX = 125°C, eJA = 250°C/ W, eJC = 90°C/ W RUN 1 KB3408-ADJ GND 2 Top Marking SW 3 A19x Marking GND 2 Marking RUN 1 ORDER PART NUMBER KB3408B-1.8 TOP VIEW 5 VOUT Top Marking xxxx 4 VIN S5 PACKAGE 5-LEAD PLASTIC TSOT-23 KB3408B-3.3 Top Marking TJMAX = 125°C, eJA = 250°C/ W, eJC = 90°C/ W x: DateCode xxxx ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. VIN = 3.6V unless otherwise specified. SYMBOL PARAMETER IVFB Feedback Current VFB Regulated Feedback Voltage CONDITIONS MIN TYP ● KB3408 (Note 4) T A = 25°C KB3408 (Note 4) 0 °C TA ) 85°C KB3408 (Note 4) –40 °C ) TA ) 85°C ● UNITS ±30 nA 0.6120 0.6135 0.6150 V V V 0.5880 0.5865 0.5850 0.6 0.6 0.6 0.4 1 1.755 3.246 1.800 3.300 1.845 3.354 6VFB Reference Voltage Line Regulation VIN = 2.5V to 7.4V (Note 4) ● VOUT Regulated Output Voltage KB3408-1.8, I OUT = 100mA KB3408-3.3, I OUT = 100mA ● ● 6VOUT Output Voltage Line Regulation VIN = 2.5V to 7.4V ● IPK Peak Inductor Current VIN = 3V, VFB = 0.5V or VOUT = 90%, Duty Cycle < 35% VLOADREG Output Voltage Load Regulation VIN Input Voltage Range IS Input DC Bias Current Active Mode Sleep Mode Shutdown (Note 5) VFB = 0.5V or VOUT = 90%, ILOAD = 0A VFB = 0.62V or VOUT = 103%, ILOAD = 0A VRUN = 0V, VIN = 4.2V fOSC Oscillator Frequency VFB = 0.6V or VOUT = 100% VFB = 0V or VOUT = 0V RPFET RDS(ON) of P-Channel FET ISW = 100mA RNFET RDS(ON) of N-Channel FET ISW = –100mA ILSW SW Leakage VRUN = 0V, VSW = 0V or 5V, VIN = 5V ±0.01 March 2007 MAX 0.4 0.40 0.45 %/V 1 %/V 0.5 0.5 ● 2 ● 2.5 1.2 V V A % 7.4 V 250 20 0.1 400 35 1 µA µA µA 1.5 210 1.8 MHz kHz 0.4 0.5 1 0.35 0.45 1 ±1 µA KB3408 Kingbor Technology Co.,Ltd KB3408 TEL:(86)0755-26508846 FAX:(86)0755-26509052 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. VIN = 3.6V unless otherwise specified. SYMBOL PARAMETER CONDITIONS VRUN RUN Threshold ● IRUN RUN Leakage Current ● Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The KB3408 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. MIN TYP MAX UNITS 0.3 1 1.5 V ±0.01 ±1 µA Note 3: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: KB3408: T J = TA + (PD)(250°C/W) Note 4: The KB3408 is tested in a proprietary test mode that connects VFB to the output of the error amplifier. Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. TYPICAL PERFORMANCE CHARACTERISTICS (From Figure1a Except for the Resistive Divider Resistor Values) Efficiency vs Input Voltage 95 IOUT = 100mA 95 Efficiency vs Output Current Efficiency vs Output Current 100 IOUT = 10mA 95 VOUT = 1.2V VIN = 2.7V 90 85 IOUT = 350mA 80 75 70 IOUT = 0.1mA 65 VIN = 2.7V 85 EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%) 90 85 IOUT = 1mA VOUT = 1.5V 90 VIN = 4.2V 80 VIN = 3.6V 75 VIN = 4.2V 80 VIN = 3.6V 75 70 70 65 65 60 55 3 2 4 5 INPUT VOLTAGE (V) 60 0.1 6 EFFICIENCY (%) VIN = 3.6V 85 80 VIN = 4.2V 75 70 1.60 0.604 0.599 0.594 1 10 100 OUTPUT CURRENT (mA) March 2007 500 1.55 1.50 1.45 1.40 0.589 65 60 0.1 VIN = 3.6V 1.65 0.609 90 500 1.70 VIN = 3.6V VIN = 2.7V 1 10 100 OUTPUT CURRENT (mA) Oscillator Frequency vs Temperature 0.614 VOUT = 2.5V REFERENCE VOLTAGE (V) 95 60 0.1 500 Reference Voltage vs Temperature Efficiency vs Output Current 100 1 10 100 OUTPUT CURRENT (mA) FREQUENCY (MHz) 50 VOUT = 1.8V 0.584 –50 –25 1.35 50 25 75 0 TEMPERATURE (°C) 3 100 125 1.30 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 Kingbor Technology Co.,Ltd KB3408 TEL:(86)0755-26508846 FAX:(86)0755-26509052 TYPICAL PERFORMANCE CHARACTERISTICS (From Figure 1a Except for the Resistive Divider Resistor Values) Start-Up from Shutdown RUN 2V/DIV VOUT 2V/DIV Load Step Load Step VOUT 100mV/DIV AC COUPLED VOUT 100mV/DIV AC COUPLED ILOAD 500mA/DIV VIN = 3.6V VOUT = 1.8V ILOAD = 350mA 40µs/DIV IL 500mA/DIV IL 500mA/DIV ILOAD 500mA/DIV ILOAD 500mA/DIV VIN = 3.6V 20µs/DIV VOUT = 1.8V ILOAD = 50mA TO 350mA VIN = 3.6V 20µs/DIV VOUT = 1.8V ILOAD = 0mA TO 350mA Load Step Load Step VOUT 100mV/DIV AC COUPLED VOUT 100mV/DIV AC COUPLED IL 500mA/DIV IL 500mA/DIV ILOAD 500mA/DIV ILOAD 500mA/DIV VIN = 3.6V 20µs/DIV VOUT = 1.8V ILOAD = 100mA TO 350mA VIN = 3.6V 20µs/DIV VOUT = 1.8V ILOAD = 200mA TO 350mA PIN FUNCTIONS RUN (Pin 1): Run Control Input. Forcing this pin above 1.5V enables the part. Forcing this pin below 0.3V shuts down the device. In shutdown, all functions are disabled drawing <1µA supply current. Do not leave RUN floating. GND (Pin 2): Ground Pin. SW (Pin 3): Switch Node Connection to Inductor. This pin connects to the drains of the internal main and synchronous power MOSFET switches. 4 VIN (Pin 4): Main Supply Pin. Must be closely decoupled to GND, Pin 2, with a 2.2µF or greater ceramic capacitor. VFB (Pin 5) (kB3408): Feedback Pin. Receives the feedback voltage from an external resistive divider across the output. VOUT (Pin 5) (kB3408-1.8/kB3408-3.3): Output Voltage Feedback Pin. An internal resistive divider divides the output voltage down for comparison to the internal reference voltage. March 2007 Kingbor Technology Co.,Ltd KB3408 TEL:(86)0755-26508846 FAX:(86)0755-26509052 SIMPLIFIED BLOC DIAGRAM SLOPE COMP 0.65V OSC OSC 4 VIN FREQ SHIFT – VFB /VOUT + 5 0.6V R1 – + 0.4V – EA FB SLEEP S Q R Q RS LATCH VIN RUN SWITCHING LOGIC AND BLANKING CIRCUIT ANTISHOOTTHRU 3 SW 0.6V REF + 1 ICOMP BURST R2 51 + – + SHUTDOWN IRCMP – TYPICAL APPLICATION Tiny 3.3V/350mA Buck Regulator VIN 3.6V to 7.4V 4 + CIN 4.7µF SW VIN 3 4.7µH VOUT 3.3V 350mA 22pF COUT** 10µF CER KB3408 1 VFB RUN 5 450k GND 100k 2 ** TAIYO YUDEN JMK316BJ106ML 100 VIN = 5V 95 VOUT = 3.3V VOUT 100mV/DIV AC COUPLED EFFICIENCY (%) 90 IL 500mA/DIV 85 80 ILOAD 500mA/DIV 75 70 VIN = 5V 20µs/DIV VOUT = 3.3V ILOAD = 200mA TO 350mA 65 60 0.1 March 2007 1 10 100 OUTPUT CURRENT (mA) 500 5 2 GND Kingbor Technology Co.,Ltd KB3408 TEL:(86)0755-26508846 FAX:(86)0755-26509052 PACAGE DESCRIPTION S5 Package 5-Lead Plastic TSOT-23(SOT23-5) 0.62 MAX 0.95 REF 2.90 BSC (NOTE 4) 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 1.90 BSC 0.09 – 0.20 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193 Kingbor Technology TEL:(86)0755-26508846 FAX:(86)0755-26509052 www.kingbor.com 6 March 2007