전자부품 데이터시트 검색엔진 |
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L6910 데이터시트(PDF) 5 Page - STMicroelectronics |
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L6910 데이터시트(HTML) 5 Page - STMicroelectronics |
5 / 29 page 5/29 L6910 - L6910A 4 DEVICE DESCRIPTION The device is an integrated circuit realized in BCD technology. The controller provides complete con- trol logic and protection for a high performance step-down DC-DC converter. It is designed to drive N Channel Mosfets in a synchronous-rectified buck topology. The output voltage of the converter can be precisely regulated down to 900mV with a maximum tolerance of ±1.5% when the internal reference is used (simply connecting together EAREF and VREF pins). The device allows also using an external reference (0.9V to 3V) for the regulation. The device provides voltage-mode control with fast transient response. It includes a 200kHz free-running oscillator that is adjustable from 50kHz to 1MHz. The er- ror amplifier features a 10MHz gain-bandwidth product and 10V/ µs slew rate that permits to realize high converter bandwidth for fast transient performance. The PWM duty cycle can range from 0% to 100%. The device protects against over-current conditions entering in HICCUP mode. The device monitors the current by using the rDS(ON) of the upper MOSFET(s) that eliminates the need for a cur- rent sensing resistor. The device is available in SO16 narrow package. 4.1 Oscillator The switching frequency is internally fixed to 200kHz. The internal oscillator generates the triangular waveform for the PWM charging and discharging with a constant current an internal capacitor. The current delivered to the oscillator is typically 50 µA (Fsw = 200KHz) and may be varied using an external resistor (RT) connected between OSC pin and GND or VCC. Since the OSC pin is maintained at fixed voltage (typ. 1.235V), the frequency is var- ied proportionally to the current sunk (forced) from (into) the pin. In particular connecting RT vs. GND the frequency is increased (current is sunk from the pin), according to the following relationship: Connecting RT to VCC = 12V or to VCC = 5V the frequency is reduced (current is forced into the pin), according to the following relationships: VCC = 12V VCC = 5V Switching frequency variation vs. RT are repeated in Fig. 4. Note that forcing a 50 µA current into this pin, the device stops switching because no current is delivered to the oscillator. Figure 4. f OS C,RT 200KHz 4.94 10 6 ⋅ R T K Ω () ------------------------- + = f OS C,RT 200KHz 4.306 10 7 ⋅ R T K Ω () ----------------------------- – = f OS C,RT 200KHz 15 10 6 ⋅ R T K Ω () --------------------- – = 10 100 1000 Frequency [kHz] 10 100 1000 10000 RT to GND RT to VCC=12V RT to VCC=5V |
유사한 부품 번호 - L6910_05 |
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유사한 설명 - L6910_05 |
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