High Efficiency 1.2MHz
2A Step Up Converter
FEATURES
• Integrated 80m Ω Power MOSFET
• 2V to 24V Input Voltage
• 1.2MHz Fixed Switching Frequency • Internal 4A Switch Current Limit • Adjustable Output Voltage • Internal Compensation • Up to 28V Output Voltage
• Automatic Pul Frequency Modulation Mode at Light Loads • up to 96% Efficiency
• Available in a 6-Pin SOT23-6 Package
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APPLICATIONS
• Battery-Powered Equipment
• Set-Top Boxed • LCD Bais Supply
• DSL and Cable Modems and Routers • Networking cards powered from PCI or PCI express slots
TYPICAL APPLICATION
Figure 1. Basic Application Circuit
The SX1308 is a constant frequency, 6-pin SOT23 current mode step-up converter intended for small, low power applications. The SX1308 switches at 1.2MHz and allows the u of tiny, low cost capacitors and inductors 2mm or less in height. Internal soft-start results in small inrush current and extends battery life.
The SX1308 features automatic shifting to pul frequency modulation mode at light loads. The SX1308 includes under-voltage lockout, current limiting, and thermal overload protection to prevent damage in the event of an output overload. The SX1308 is available in a small 6-pin SOT-23 package.
Efficiency
Iout (mA)
Figure 2. Efficiency Curve
E f f i c i e n c y (%)
GENERAL DESCRIPTION
SX1308
IN, EN voltages ………..….…… -0.3V to 26V Operating Temperature….... -40°C to +85°C FB Voltages ................................-0.3V to 6V Junction Temperature ………………...160°C
SW Voltage ……………………..-0.3V to 30V Storage Temperature Range -65°C to 150°C Peak SW Sink and Source Current ………4A Lead Temperature (Soldering, 10s) ...+300°C
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清蒸鲈鱼的制作方法PACKAGE/ORDER INFORMATION
3
124
6SOT23-5IN
GND
FB
SW
EN
(MT3540)5
NC
PIN DESCRIPTION
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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我的好朋友英语作文
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 ud, connect EN to the input supply for automatic startup.
5 IN Input Supply Pin. Must be locally bypasd. 6
NC
NC
ABSOLUTE MAXIMUM RATINGS SOT23-6 (SX1308)
ELECTRICAL CHARACTERISTICS
(V IN=V EN=5V, T A = 25°C, unless otherwi 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 mΩSW 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.
The SX1308 us a fixed frequency, peak current mode boost regulator architecture to regulate voltage at the feedback pin. The operation of the SX1308 can be understood by referring to the block diagram of Figure 3. At the start of each oscillator cycle the MOSFET is turned on through the control circuitry. To prevent sub-harmonic oscillations at duty cycles greater than 50 percent, a stabilizing ramp is added to the output of the current n amplifier and the result is fed into the negative input of the PWM comparator. When this voltage equals
The output voltage of the error amplifier the power
MOSFET is turned off. The voltage at the output of the error amplifier is an amplified version of the difference between the 0.6V bandgap reference voltage and the feedback voltage. In this way the peak current level keeps the output in regulation. If the feedback voltage starts to drop, the output of the error amplifier increas. The results in more current to flow through the power MOSFET, thus increasing the power delivered to the output. The
SX1308 has internal soft start to limit the amount of input current at startup and to also limit the amount of overshoot on the output.
Figure 3. Functional Block Diagram
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TYPICAL OPERATING CHARACTERISTICS
Efficiency Curve
Iout (mA)
line Regulation
Vin (V)
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Freq VS Vin
Efficiency Curve
Iout(mA)
Load regualation
Iout (mA)
Efficiency VS Vin
E f f i c i e n c y
V o u t (V )
C u r r e n t l i m i t (A )
V o u t (
V )梦见鬼上身
SX1308
