[图文]TG1611XC9216CE8506EUP3406

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[图文]TG1611XC9216CE8506EUP3406

宏碁3820tg的详细标识
宏碁3820tg的详细标识

降压芯片 TG1611The TG1611 is a high performance 800mA 1.5MHz monolithic step-down converter.The TG1611 requires only three external power components (Cin, Cout and L). The adjustable version can be programmed with external feedback to any voltage, ranging from 0.6V to the input voltage. At dropout, the converter duty cycle increases to 100% and the output voltage tracks the input voltage minus the Rdson drop of the high-side MOSFET. The internal error amplifier and compensation provides excellent transient response, load, and line regulation. Soft start function prevents input inrush current and output overshoot during start up. The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency should be less than input source impedance to prevent high frequency switching current passing to the input.R1 ) R2VOUT  0.6  (1 R1  (VOUT / 0.6  1)  R2Output Noise ( 10mV/DIV 200ns/DIV AC COUPLED)Output Noise( 100mV/DIV 2ms/DIV AC COUPLED)

TG1611XC9216CE8506EUP3406

降压芯片Output and Input Capacitor SelectionXC9216In continuous mode, the source current of the top MOSFET is a square wave of duty cycle V OUT /VIN. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by:This formula has a maximum at VIN = 2VOUT , where IRMS = IOUT /2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Note that the capacitor manufacturer’s ripple current ratings are often based on 2000 hours of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Always consult the manufacturer if there is any question. The selection of COUT is driven by the required effective series resistance (ESR). Typically, once the ESR requirement for C OUT has been met, the RMS current rating generally far exceeds the IRIPPLE(P-P) requirement. The output ripple ΔVOUT is determined by:The VIN quiescent current is due to two components: the DC bias current as given in the electrical characteristics and the internal main switch and synchronous switch gate charge currents. The gate charge current results from switching the gate capacitance of the internal power MOSFET switches. Each time the gate is switched from high to low to high again, a packet of charge △Q moves from VIN to ground. The resulting △Q/△t is the current out of VIN that is typically larger than the DC bias current. In continuous mode, IGATECHG = f (QT +QB) where QT and QB are the gate charges of the internal top and bottom switches. Both the DC bias and gate charge losses are proportional to VIN and thus their effects will be more pronounced at higher supply voltages.

TG1611XC9216CE8506EUP3406

降压芯片 CE8506This formula has a maximum at V IN = 2VOUT , where IRMS = IOUT /2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Note that the capacitor manufacturer’s ripple current ratings are often based on 2000 hours of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Always consult the manufacturer if there is any question. The selection of COUT is driven by the required effective series resistance (ESR). Typically, once the ESR requirement for C OUT has been met, the RMS current rating generally far exceeds the IRIPPLE(P-P) requirement. The output ripple ΔVOUT is determined by:Efficiency vs. Output Current (Vout=1.8V) 100 90 80 Output Voltage (V) 70 60 VIN=2.7V c ency 50 40 30 20 10 0 0 100 200 300 400 500 600 700 Output Current (mA) VIN=3.6V VIN=4.2V 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0Output Voltage vs. Load Current (Vin=3.6V, Vout=1.8V)100 200 300 400 500 600 700 800 Load Current (mA)

TG1611XC9216CE8506EUP3406

降压芯片 EUP3406Application InformationMain Control Loop The EUP3406 uses a slop-compensated constant frequency, current mode PWM architecture. Both the main (P-Channel MOSFET) and synchronous (N-channel MOSFET) switches are internal. During normal operation, the EUP3406 regulates output voltage by switching at a constant frequency and then modulating the power transferred to the load each cycle using PWM comparator. It sums three weighted differential signals: the output feedback voltage from an external resistor divider, the main switch current sense, and the slope-compensation ramp. It modulates output power by adjusting the inductor-peak current during the first half of each cycle. An N-channel, synchronous switch turns on during the second half of each cycle (off time). When the inductor current starts to reverse or when the PWM reaches the end of the oscillator period, the synchronous switch turns off. This keep excess current from flowing backward through the inductor, from the output capacitor to GND, or through the main and synchronous switch to GND. Inductor Selection The output inductor is selected to limit the ripple current to some predetermined value, typically 20%~40% of the full load current at the maximum input voltage. Large value inductors lower ripple currents. Higher VIN or VOUT also increases the ripple current as shown in equation. A reasonable starting point for setting ripple current is ∆IL=240mA (40% of 600mA). The input capacitor RMS current varies with the input voltage and the output voltage. The equation for the maximum RMS current in the input capacitor is:GENERAL DESCRIPTIONIRMS=IO× V V O × 1 − O  V  V IN IN     The output capacitor COUT has a strong effect on loop stability. The selection of COUT is driven by the required effective series resistance (ESR). ESR is a direct function of the volume of the capacitor; that is, physically larger capacitors have lower ESR. Once the ESR requirement for COUT has been met, the RMS current rating generally far exceeds the IRIPPLE(P-P) requirement. The output ripple ∆VOUT is determined by:∆V ≅ ∆I  ESR + L OUT 8fC    OUT 1When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best temperature and voltage characteristics of all the ceramics for a given value and size.∆IL= V 1 − OUT V OUT  (f)(L) V  IN1   

TG1611XC9216CE8506EUP3406

TG1611XC9216CE8506EUP3406