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
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
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-23-6 -40 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
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 4.5 18 V Maximum Output Current I OUT (MAX) 1.5 A Operating Ambient Temperature T A -40 85 ºC 4
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 4.5 18 V Quiescent Current I Q V FB =0.9V 0.8 1.1 ma Shutdown Supply Current I SHDN V EN =0V 0.1 1.0 μa Feedback Voltage V FB 0.785 0.810 0.835 V Feedback Over Voltage Threshold V FBOV 0.972 V Feedback Bias Current I FB V FB =0.85V -0.1 0.1 μa Switch On-resistance R DSON I SW =1A 0.35 Ω V Switch Leakage Current I IN =18V, LEAK 0.1 10 μa V EN =0V Switch Current Limit IM 1.8 2.4 A EN Pin Threshold V ENH 1.5 V ENL 0.4 Input UVLO Threshold V UVLO V IN Rising 3.3 3.8 4.3 V Input UVLO Hysteresis V HYS 0.2 V Oscillator Frequency f OSC1 1.1 1.4 1.7 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
Typical Performance Characteristics T A =25ºC, V IN =12V, V EN =5V, =3.3V, unless otherwise noted. 100 1.10 90 1.05 80 1.00 Efficiency (%) 70 60 50 40 30 20 V IN =12V, =3.3V V IN =12V, =5V Quiescent Current (ma) 0.95 0.90 0.85 0.80 0.75 0.70 V IN =12V V FB =0.9V 10 0.65 V EN =5V 0 0.01 0.1 0.5 1 2 Output Current (A) 0.60-60 -40-20 0 20 40 60 80 100 120 140 160 Temperature ( o C) Figure 4. Efficiency vs. Output Current Figure 5. Quiescent Current vs. Temperature 0.96 3.8 0.88 3.6 Feedback Voltage (V) 0.80 0.72 0.64 0.56 0.48 Output Voltage (V) 3.4 3.2 3.0 2.8 2.6 2.4 V IN =12V, =3.3V 0.40-60 -40-20 0 20 40 60 80 100 120 140 160 Temperature ( o C) 2.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 Output Current (A) Figure 6. Feedback Voltage vs.temperature Figure 7. Output Voltage vs. Output Current 6
Typical Performance Characteristics (Continued) T A =25ºC, V IN =12V, V EN =5V, =3.3V, unless otherwise noted. Output Voltage (V) 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 2.7 2.6 I OUT =1.2A I OUT =1.5A 4 6 8 10 12 14 16 18 20 Input Voltage (V) Maximum Output Current (A) 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 =3.3V 0.4 0.2 4 6 8 10 12 14 16 18 20 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
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
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
Typical Application Figure 18. Typical Application Circuit of 10
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 8 0.200(0.008) 6 5 4 0.300(0.012) 0.600(0.024) Pin 1 Mark 1 2 3 0.700(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
Mounting Pad Layout SOT-23-6 Z G X Y E Dimensions (mm)/(inch) (mm)/(inch) (mm)/(inch) (mm)/(inch) (mm)/(inch) Value 3.600/0.142 1.600/0.063 0.700/0.028 1.000/0.039 0.950/0.037 12
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