1.5A ASYNCHRONOUS DC-DC BUCK CONV

Transcription

1 General Description The is a 1.4MHz fixed frequency, current mode, PWM buck (step-down) DC-DC converter, capable of driving a 1.5A load with high efficiency, excellent line and load regulation. The device integrates N-channel power MOSFET switch with low on-resistance. Current mode control provides fast transient response and cycle-by-cycle current limit. 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. The is available in SOT-23-6 package. Features Input Voltage Range: 4.5V to 18V Output Voltage Adjustable from 0.81V to 15V Fixed 1.4MHz Frequency High Efficiency: up to 92% Output Current: 1.5A Current Mode Control Built-in Over Current Protection Built-in Thermal Shutdown Function Built-in UVLO Function Built-in Over Voltage Protection Built-in Soft-start Applications LCD TV DPF Portable DVD SOT-23-6 Figure 1. Package Type of 1

2 Pin Configuration K Package (SOT-23-6) Pin 1 Mark BS 1 6 SW GND 2 5 IN FB 3 4 EN Figure 2. Pin Configuration of (Top View) Pin Description Pin Number Pin Name Function 1 BS 2 GND Ground pin 3 FB 4 EN 5 IN 6 SW Bootstrap pin. A bootstrap capacitor is connected between the BS pin and SW pin. The voltage across the bootstrap capacitor drives the internal high-side NMOS switch Feedback pin. This pin is connected to an external resistor divider to program the system output voltage. When V FB exceeds 20% of the nominal regulation value of 0.81V, the OVP is triggered. When V FB <0.25V, the oscillator frequency is lowered to realize short circuit protection Control input pin. Forcing this pin above 1.5V enables the IC. Forcing this pin below 0.4V shuts down the IC. When the IC is in shutdown mode, all functions are disabled to decrease the supply current below 1μA Supply input pin. A capacitor should be connected between the IN pin and GND to keep the DC input voltage constant Power switch output pin. This pin is connected to the inductor and bootstrap capacitor 2

3 Functional Block Diagram Figure 3. Functional Block Diagram of Ordering Information - Circuit Type Package K: SOT-23-6 G1: Green TR: Tape & Reel Package Temperature Range Part Number Marking ID Packing Type SOT to 85 C KTR-G1 GCI 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 Pin Voltage V IN -0.3 to 20 V EN Pin Voltage V EN -0.3 to V IN +0.3 V SW Pin Voltage 21 V Bootstrap Pin Voltage V BS -0.3 to +6 V Feedback Pin Voltage V FB -0.3 to 6V V Thermal Resistance θ JA 220 ºC/W Operating Junction Temperature T J 150 ºC Storage Temperature T STG -65 to 150 ºC Lead Temperature (Soldering, 10sec) T LEAD 260 ºC ESD (Human Body Model) 2000 V ESD (Machine Model) 200 V 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 IN V Maximum Output Current I OUT (MAX) 1.5 A Operating Ambient Temperature T A ºC 4

5 Electrical Characteristics V IN =V EN =12V, =3.3V, T A =25ºC, unless otherwise specified. Parameter Symbol Conditions Min Typ Max Unit Input Voltage V IN V Quiescent Current I Q V FB =0.9V ma Shutdown Supply Current I SHDN V EN =0V μa Feedback Voltage V FB V Feedback Over Voltage Threshold V FBOV V Feedback Bias Current I FB V FB =0.85V μa Switch On-resistance R DSON I SW =1A 0.35 Ω V Switch Leakage Current I IN =18V, LEAK μa V EN =0V Switch Current Limit IM A EN Pin Threshold V ENH 1.5 V ENL 0.4 Input UVLO Threshold V UVLO V IN Rising V Input UVLO Hysteresis V HYS 0.2 V Oscillator Frequency f OSC MHz f OSC2 Short Circuit 460 khz Max. Duty Cycle D MAX V FB =0.6V 90 % Min. Duty Cycle D MIN V FB =0.9V 0 % Minimum On Time t ON 100 ns Thermal Shutdown T OTSD 160 ºC Thermal Shutdown Hysteresis T HYS 20 ºC Soft-start Time t SS 200 μs Note 2: R DSON, t ON, T OTSD, T HYS and t SS are guaranteed by design. V 5

6 Typical Performance Characteristics T A =25ºC, V IN =12V, V EN =5V, =3.3V, unless otherwise noted Efficiency (%) V IN =12V, =3.3V V IN =12V, =5V Quiescent Current (ma) V IN =12V V FB =0.9V V EN =5V Output Current (A) Temperature ( o C) Figure 4. Efficiency vs. Output Current Figure 5. Quiescent Current vs. Temperature Feedback Voltage (V) Output Voltage (V) V IN =12V, =3.3V Temperature ( o C) Output Current (A) Figure 6. Feedback Voltage vs.temperature Figure 7. Output Voltage vs. Output Current 6

7 Typical Performance Characteristics (Continued) T A =25ºC, V IN =12V, V EN =5V, =3.3V, unless otherwise noted. Output Voltage (V) I OUT =1.2A I OUT =1.5A Input Voltage (V) Maximum Output Current (A) =3.3V Input Voltage (V) Figure 8. Output Voltage vs. Input Voltage Figure 9. Maximum Output Current vs. Input Voltage (AC) 20mV/div 5V/div (AC) 100mV/div V IN 10V/div Time (400ns/div) Time (100μs/div) Figure 10. Output Ripple (I OUT =1.5A) Figure 11.Load Transient (I OUT =1 to 1.5A) 7

8 Typical Performance Characteristics (Continued) T A =25ºC, V IN =12V, V EN =5V, =3.3V, unless otherwise noted. V EN 3.8V/div 1V/div 5V/div V EN 3.4V/div 1V/div 5V/div Time (100μs/div) Time (10μs/div) Figure 12. Enable Turn-on Characteristic (Resistance Load, R LOAD =2.6Ω) Figure 13. Enable Turn-off Characteristic (Resistance Load, R LOAD =2.6Ω) 2V/div V FB 1V/div 10V/div 2V/div V FB 1V/div 10V/div Time (400μs/div) Time (400μs/div) Figure 14. Short Circuit Protection (I OUT =1.5A) Figure 15.Short Circuit Recovery (R LOAD =2.6Ω) 8

9 Typical Performance Characteristics (Continued) T A =25ºC, V IN =12V, V EN =5V, =3.3V, unless otherwise noted. V FB 500mV/div 2V/div 10V/div V FB 500mV/div 2V/div 10V/div Time (20μs/div) Time (200μs/div) Figure 16. Over Voltage Protection (I OUT =1.5A) Figure 17. Over Voltage Recovery (I OUT =1.5A) 9

10 Typical Application Figure 18. Typical Application Circuit of 10

11 Mechanical Dimensions SOT-23-6 Unit: mm(inch) 2.820(0.111) 3.100(0.122) 0.300(0.012) 0.500(0.020) (0.008) (0.012) 0.600(0.024) Pin 1 Mark (0.028)REF 0.950(0.037)TYP 1.800(0.071) 2.000(0.079) 0.000(0.000) 0.150(0.006) 0.100(0.004) 0.200(0.008) 0.900(0.035) 1.300(0.051) 1.450(0.057) MAX 11

12 Mounting Pad Layout SOT-23-6 Z G X Y E Dimensions (mm)/(inch) (mm)/(inch) (mm)/(inch) (mm)/(inch) (mm)/(inch) Value 3.600/ / / / /

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 IMPORTANT NOTICE 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 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 other rights nor the rights of others. MAIN SITE - of Headquarters any its products or circuits. BCD Semiconductor Manufacturing - Wafer Limited Fab does not convey any license under its patent rights or BCD other (Shanghai) rights Micro-electronics nor the rights Limited of others. Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd. No. 1600, Zi Xing Road, Shanghai ZiZhu Science-based Industrial Park, , P. R.C. 800 Yishan Road, Shanghai , China Tel: , Fax: Tel: , Fax: MAIN SITE BCD REGIONAL - Headquarters Semiconductor SALES Manufacturing OFFICE Limited - Wafer BCD FabSemiconductor Manufacturing Limited Shenzhen BCD - Wafer Semiconductor Fab Office Manufacturing Limited Taiwan Shanghai Office - IC Design SIM-BCD (Taipei) Group Semiconductor Manufacturing Co., Ltd. Shanghai No. 1600, Zi SIM-BCD Xing Road, Semiconductor Shanghai ZiZhu Manufacturing Science-based Co., Limited Industrial Ltd., Shenzhen Park, , Office China BCD 800 Semiconductor Yi Advanced Shan Road, Analog (Taiwan) Shanghai Circuits Company , (Shanghai) China Limited Corporation Unit Tel: 800, , A Yi Room Shan Road, 1203,Skyworth Shanghai Fax: Bldg., , Gaoxin ChinaAve.1.S., Nanshan District 3F, No.17, Tel: F, Lane Zone 171, B, 900, Sec. 1491, 2, Yi Fax: Jiu-Zong Shan Road, Rd., Shanghai Nei-Hu 0008Dist., , Taipei(114), China Taiwan, R.O.C Shenzhen Tel: , 1491, China Fax: Tel: Tel: , Fax: Tel: REGIONAL , SALES OFFICE Fax: Fax: / REGIONAL Shenzhen OfficeSALES OFFICE Taiwan Office USA Office Taiwan Shenzhen Shanghai Office SIM-BCD Office (Hsinchu) Semiconductor Manufacturing Co., Ltd., Shenzhen Office BCD Shanghai Unit A Semiconductor Room SIM-BCD 1203, Skyworth Semiconductor (Taiwan) Bldg., Company Gaoxin Manufacturing Limited Ave.1.S., Nanshan Co., Ltd. District, Shenzhen Shenzhen, Office 8F, Advanced China No.176, Analog Sec. 2, Gong-Dao Circuits (Shanghai) 5th Road, Corporation East District Shenzhen Office USA BCD Office Taiwan Semiconductor Office (Taiwan) Company Limited Korea OfficeUSA BCD Office Semiconductor Corp. BCD 4F, Semiconductor 298-1, BCD Rui Semiconductor Guang Corp. Road, (Taiwan) Nei-Hu District, Company Taipei, BCD Limited Semiconductor BCD Semiconductor Huntwood Limited Korea Ave. Corporation Hayward, office Taiwan Kato 4F, Road, 298-1, Fremont, Rui Guang CA Road, 94538, Nei-Hu USA District, Room Taipei, , CA Digital-Empire 94544, Huntwood USA Ave. II, 486 Hayward, Sin-dong, HsinChu Room Tel: E, City 5F, Noble 300, Taiwan, 7951 Center, No.1006, R.O.C 3rd Fuzhong Road, Futian District, Shenzhen , China Tel: Tel: Taiwan 2808 Yeongtong-Gu, CA Tel Suwon-city, : 94544, U.S.A Gyeonggi-do, Korea Tel: Fax: , Fax: Fax: Fax: Fax: Tel: Fax: Tel: Tel Fax: : Fax: