SYNCHRONOUS DC-DC BUCK CONVERTER

Transcription

1 General Description The is a 1.1MHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a 800mA load with high efficiency, excellent line and load regulation. The device integrates a main switch and a synchronous switch without an external Schottky diode. It is ideal for powering portable equipment that runs from a single Li-ion battery. A standard series of inductors are available from several different manufacturers optimized for use with the. This feature greatly simplifies the design of switch-mode power supplies. This IC is available in TSOT-23-5, MSOP-10 and DFN-2 2-6(1) packages. Features High Efficiency: up to 95% Output Current: 800mA Input Voltage Range: 2.5V to 5.5V Fixed 1.1MHz Frequency Current Mode Control 100% Duty Cycle in Dropout Built-in Short Circuit Protection Built-in Thermal Shutdown Function Built-in Current Limit Function Shutdown Current: <1µA Applications GPS WiFi Card Portable Media Player Digital Still and Video Cameras TSOT-23-5 MSOP-10 DFN-2 2-6(1) Figure 1. Package Types of 1

2 Pin Configuration KT Package MM Package DN Package TSOT-23-5 MSOP-10 DFN-2 2-6(1) P in 1 Mark EN GND FB VIN NC GND PGND SW EN NC EN FB GND SW 3 4 VIN NC FB NC NC VIN 3 4 SW Figure 2. Pin Configuration of (Top View) Pin Description Pin Number TSOT-23-5 MSOP-10 DFN-2 2-6(1) Pin Name EN GND Ground pin Function Control input pin. Forcing this pin above 1.5V enables the IC. Forcing this pin below 0.6V shuts down the IC. When the IC is in shutdown mode, all functions are disabled to decrease the supply current below 1µA SW Power switch output pin. Inductor connection to drain of the internal PFET and NFET switches VIN Supply input pin. Bypass to GND with a 10µF or greater ceramic capacitor FB Feedback pin. Connect it with an external resistor divider network to program the system output voltage 2, 4, 6, 7 1 NC No connection 10 PGND Power ground pin 2

3 Functional Block Diagram Ordering Information Figure 3. Functional Block Diagram of - Circuit Type Package KT: TSOT-23-5 MM: MSOP-10 DN: DFN-2 2-6(1) G1: Green TR: Tape & Reel ADJ: Adjustable Voltage Package Temperature Range Part Number Marking ID Packing Type TSOT-23-5 KT-ADJTRG1 L2A Tape & Reel MSOP to 85 C MM-ADJTRG1 3406AMM-G1 Tape & Reel DFN-2 2-6(1) DN-ADJTRG1 BA Tape & Reel BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant and green. 3

4 Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit Input Voltage -0.3 to 6 V Feedback Voltage V FB -0.3 to +0.3 V EN Pin Voltage V EN -0.3 to +0.3 V SW Pin Voltage V SW -0.3 to +0.3 V TSOT Thermal Resistance θ JA MSOP ºC/W DFN-2 2-6(1) 100 Operating Junction Temperature T J 150 ºC Storage Temperature T STG -65 to 150 ºC Lead Temperature (Soldering, 10sec) T LEAD 260 ºC Note 1: Stresses greater than those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to Absolute Maximum Ratings for extended periods may affect device reliability. Recommended Operating Conditions Parameter Symbol Min Max Unit Input Voltage V Maximum Output Current I OUT (MAX) 800 ma Operating Ambient Temperature T A ºC 4

5 Electrical Characteristics =V EN =3.6V, T A =25, unless otherwise specified. Specifications with boldface type apply over full operating temperature range from -40 to 85ºC. Parameters Symbol Conditions Min Typ Max Unit Supply Current I CC V FB =0.55V µa Shutdown Supply Current I SHDN V EN =0V, =5.5V µa Under Voltage Lockout Threshold Under Voltage Lockout Hysteresis V UVLO Rising edge 2.27 V V HUVLO 200 mv Feedback Bias Current I FB V FB =0.65V na Feedback Voltage V FB I OUT =100mA Maximum Output Current I OUT (MAX) =2.5V, =0.9V =3.6V, =1.2V =4.6V, =3.3V 0.588/ / Switch Current Limit I LIM V FB =0.55V A Oscillator Frequency f OSC MHz V ma EN Pin Threshold V ENL 0.6 V ENH 1.5 V EN Pin Input Leakage Current Internal PFET On Resistance Internal NFET On Resistance I H V EN =3.6V µa I L V EN =0V µa R DSONP I SW =100mA 0.44 Ω R DSONN I SW =-100mA 0.29 Ω Maximum Duty Cycle D MAX V FB =0.55V 100 % Soft-start Time Thermal Shutdown Threshold Thermal Shutdown Hysteresis T SS V EN =0V to I OUT =50mA 220 µs T OTSD 160 ºC T HYS 30 ºC 5

6 Typical Performance Characteristics L=10µH, C IN =C OUT =10µF, T A =25 o C, unless otherwise noted Frequency (MHz) =3.6V =1.8V I OUT =0A Supply Current (ma) =3.6V V FB =0.55V Input Voltage (V) Temperature ( o C) Figure 4. Frequency vs. Input Voltage Figure 5. Supply Current vs. Temperature Current Limit (A) Output Voltage (V) =3.6V V FB =0.55V =3.6V =1.8V Temperature ( O C) Output Current (A) Figure 6. Current Limit vs. Temperature Figure 7. Output Voltage vs. Output Current 6

7 Typical Performance Characteristics (Continued) 400ns/div V SW 2V/div 20mV/div V SW 2V/div 20mV/div 400ns/div 400ns/div Figure 8. Light Load Operation Figure 9. Heavy Load Operation ( =3.6V, =1.8V, I OUT =0mA) ( =3.6V, =1.8V, I OUT =800mA) I OUT 500mA/div 100mV/div I IN 500mA/div 2V/div V EN 2V/div 200µs/div 400µs/div Figure 10. Load Transient Figure 11. Start up from Shutdown ( =3.6V, =1.8V, I OUT =0mA to 800mA) ( =3.6V, =1.8V, R LOAD =2.5Ω) 7

8 Typical Performance Characteristics (Continued) 1V/div V SW 2V/div I L 1A/div 1V/div V SW 2V/div I L 1A/div 10µs/div 40µs/div Figure 12. Short Circuit Protection Figure 13. Short Circuit Recovery ( =3.6V, =1.8V, no load) ( =3.6V, =1.8V, no load) Efficiency (%) TSOT-23-5 MSOP-10 Efficiency (%) TSOT-23-5 MSOP =3.6V =1.8V L=10µH =4.2V =3.3V L=10µH Output Current (A) Output Current (A) Figure 14. Efficiency vs. Output Current Figure 15. Efficiency vs. Output Current 8

9 Typical Performance Characteristics (Continued) 2.0 Normalized Feedback Voltage (%) =3.6V =1.8V Temperature ( o C) Figure 16. Normalized Feedback Voltage vs. Temperature Typical Application 150k R2 300k R1 2.5V to 5.5V C IN 10µF EN FB VIN -ADJ GND SW L 10µH C OUT 10µF 1.8V 800mA Figure 17. Typical Application of 9

10 Mechanical Dimensions TSOT-23-5 Unit: mm(inch) 5 GAUGE PLANE 10

11 Mechanical Dimensions (Continued) MSOP-10 Unit: mm(inch) 11

12 Mechanical Dimensions (Continued) DFN-2 2-6(1) Unit: mm(inch) 1.900(0.075) 2.100(0.083) 0.200(0.008) MIN (0.026) N4 TYP. N5 N (0.009) 0.376(0.015) 1.500(0.059) 1.700(0.067) 1.900(0.075) 2.100(0.083) 0.850(0.033) 1.050(0.041) Pin 1 Mark PIN #1 IDENTIFICATION See DETAIL A N3 N2 N (0.010) 0.350(0.014) 0.000(0.000) 0.050(0.002) DETAIL A (0.022) 0.650(0.026) 0.152(0.006) REF. Pin 1 options 12

13 IMPORTANT NOTICE reserves the right to make changes without further notice to any products or specifications herein. does not assume any responsibility for use of any its products for any particular purpose, nor does assume any liability arising out of the application or use of any its products or circuits. does not convey any license under its patent rights or other rights nor the rights of others. MAIN SITE BCD - Headquarters Semiconductor Manufacturing Limited - Wafer BCD FabSemiconductor Manufacturing Limited BCD - Wafer Semiconductor Fab Manufacturing Limited Shanghai - IC Design SIM-BCD Group Semiconductor Manufacturing Co., Ltd. No. Shanghai 1600, Zi SIM-BCD Xing Road, Semiconductor Shanghai ZiZhu Manufacturing Science-based Limited Industrial Park, , China 800 Yi Advanced Shan Road, Analog Shanghai Circuits , (Shanghai) China Corporation Tel: 800, , Yi Shan Road, Shanghai Fax: , China Tel: F, Zone B, 900, 1491, Yi Fax: Shan Road, Shanghai , China Tel: , Fax: Tel: , Fax: REGIONAL SALES OFFICE REGIONAL Shenzhen OfficeSALES OFFICE Shenzhen Shanghai SIM-BCD Office Semiconductor Manufacturing Co., Ltd., Shenzhen Office Shanghai Unit A Room SIM-BCD 1203, Skyworth Semiconductor Bldg., Gaoxin Manufacturing Ave.1.S., Nanshan Co., Ltd. District, Shenzhen Shenzhen, Office Advanced China Analog Circuits (Shanghai) Corporation Shenzhen Office Taiwan Office BCD Taiwan Semiconductor Office (Taiwan) Company Limited 4F, 298-1, BCD Rui Semiconductor Guang Road, (Taiwan) Nei-Hu District, Company Taipei, Limited Taiwan 4F, 298-1, Rui Guang Road, Nei-Hu District, Taipei, USA Office USA BCD Office Semiconductor Corp. BCD Semiconductor Huntwood Ave. Corporation Hayward, CA 94544, Huntwood USA Ave. Hayward, Room Tel: E, 5F, Noble 7951 Center, No.1006, 3rd Fuzhong Road, Futian District, Shenzhen , China Tel: Taiwan 2808 CA Tel : 94544, U.S.A Tel: Fax: Fax: Fax: Tel: Fax: Tel Fax: : Fax: