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IN, EN voltages … …… ..….…… - 0.3V to 26V Operating Temperature… .... -40°C to +85°C Junction Temperature ………………... 160°C Storage Temperature Range -65°C to 150°C Peak SW Sink and Source Current … ……4 A Lead Temperature (Soldering, 10s) ...+300°C PACKAGE/ORDER INFORMATION SOT23-5 INGND FB SW EN (MT3540) NC PIN DESCRIPTION PIN NAME FUNCTION 1 SW Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and 28V.
2 GND Ground Pin
3 FB Feedback Input. The FB voltage is 0.6V. Connect a resistor divider to FB. 4 EN Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns it off. When not used, connect EN to the input supply for automatic startup. 5 IN Input Supply Pin. Must be locally bypassed.
6 NC NC
( ) SDB628 www.shouding.net SDB628 Shouding SD.14
ELECTRICAL CHARACTERISTICS
=5V, T A = 25°C, unless otherwise noted.) Parameter Conditions MIN TYP MAX unit Operating Input Voltage 2 24 V Under Voltage Lockout 1.98 V Under Voltage Lockout Hysteresis 100 mV Current (Shutdown) V EN = 0V 0.1 1 µA Quiescent Current (PFM) V FB =0.7V，No switch 100 200 µA Quiescent Current (PWM) V FB =0.5V，switch 1.6 2.2 mA Switching Frequency 1.2 MHz Maximum Duty Cycle V FB = 0V 90 % EN Input High Voltage 1.5 V EN Input Low Voltage 0.4 V FB Voltage 0.588 0.6 0.612 V FB Input Bias Current V FB = 0.6V -50 -10 nA SW On Resistance (1) 80 150 mΩ SW Current Limit (1) V IN = 5V, Duty cycle=50% 4 A SW Leakage V SW = 20V 1 μA Thermal Shutdown 155 ℃ Note: 1) Guaranteed by design, not tested. www.shouding.net SDB628 Shouding SD.14
Figure 3. Functional Block Diagram
TYPICAL OPERATING CHARACTERISTICS Efficiency Curve Iout (mA) line Regulation Vin (V) Freq VS Vin Efficiency Curve Iout(mA) Load regualation Iout (mA) Efficiency VS Vin Efficiency V out( V Current limit(A) Vout V www.shouding.net SDB628 Shouding SD.14
Setting the Output Voltage The internal reference VREF is 0.6V (Typical).The output voltage is divided by a resistor divider,R1 and R2 to the FB pin. The output voltage is given by ) 1 ( R RV V REFOUT + × = Inductor Selection The recommended values of inductor are 4.7 to 22μH. Small size and better efficiency are the major concerns for portable device, such as used for mobile phone. The inductor should have low core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation current rating should be considered. Capacitor Selection Input and output ceramic capacitors of 22μF are recommended for applications. For better voltage filtering, ceramic capacitors with low ESR are recommended. X5R and X7R types are suitable because of their wider voltage and temperature ranges. Diode Selection Schottky diode is a good choice for because of its low forward voltage drop and fast reverses recovery. Using Schottky diode can get better efficiency. The high speed rectification is also a good characteristic of Schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of the peak current and output average current multiplication as following : PEAKOUTD I I RMS I× ≈) ( The diode’ s reverse breakdown voltage should be larger than the output voltage. Layout Consideration For best performance of the , the following guidelines must be strictly followed. Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. The GND should be connected to a strong ground plane for heat sinking and noise protection. Keep the main current traces as possible as short and wide. SW node of DC -DC converter is with high frequency voltage swing. It should be kept at a small area. Place the feedback components as close as possible to the IC and k eep away from the noisy devices.
APPLICATION INFORMATION
www.shouding.net SDB628 Shouding SD.14
Figure 4. TSOT23-6/SOT23-6 Physical Dimensions 1)ALL DIMENSIONS ARE IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,PROTRUSION OR GATE BURR. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. 4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.10 MILLIMETERS MAX. 5) DRAWING CONFORMS TO JEDEC MO-193, VARIATION AB.