データシートサーチシステム |
|
MP1497S データシート(PDF) 9 Page - Monolithic Power Systems |
|
MP1497S データシート(HTML) 9 Page - Monolithic Power Systems |
9 / 15 page MP1497S – SYNCHRONOUS, STEP-DOWN CONVERTER WITH INTERNAL MOSFETS MP1497S Rev. 1.01 www.MonolithicPower.com 9 9/7/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. OPERATION The MP1497S is a high-frequency, synchronous, rectified, step-down, switch-mode converter with built-in power MOSFETs. It offers a very compact solution to achieve 3A continuous output current with excellent load and line regulation over a wide input supply range. The MP1497S operates in a fixed-frequency, peak-current–control mode to regulate the output voltage. The internal clock initiates a PWM cycle. The integrated high-side power MOSFET turns on and remains on until its current reaches the value set by the COMP voltage. When the power switch is off, it remains off until the next clock cycle starts. If the current in the power MOSFET does not reach the COMP set current value within 95% of one PWM period, the power MOSFET will be forced to turn off. Internal Regulator The 5V internal regulator powers most of the internal circuitries. This regulator takes the VIN input and operates in the full VIN range. When VIN exceeds 5.0V, the output of the regulator is in full regulation. When VIN is below 5.0V, the output decreases and requires a 0.1µF ceramic decoupling capacitor. Error Amplifier The error amplifier compares the FB pin voltage against the internal 0.8V reference (REF) and outputs a COMP voltage that controls the power MOSFET current. The optimized internal compensation network minimizes the external component counts and simplifies the control loop design. Enable/SYNC Control EN is a digital control pin that turns the regulator on and off. Drive EN high to turn on the regulator, drive it low to turn it off. An internal 1MΩ resistor from EN to GND allows EN to float to shut down the chip. The EN pin is clamped internally using a 6.5V series-Zener-diode as shown in Figure 2. Connecting the EN pin through a pullup resistor to any voltage connected to VIN limits the EN input current to less than 100µA. For example, when connecting VIN to a 12V source, RPULLUP≥[(12V – 6.5V) ÷ 100µA = 55kΩ]. Connecting the EN pin directly to a voltage source without any pullup resistor requires limiting the amplitude of the voltage source to below 6.5V to prevent damaging the Zener diode. EN/SYNC EN LOGIC Zener 6.5V-typ GND Figure 2: Zener Diode Circuit For external clock synchronization, connect a clock with a frequency range of 300kHz and 2MHz 2ms after the output voltage is set: The internal clock rising edge will synchronize with the external clock rising edge. Select an external clock signal with a pulse-width less than 1.7μs. Under-Voltage Lockout Under-voltage lockout (UVLO) protects the chip from operating at an insufficient supply voltage. The MP1497S UVLO comparator monitors the output voltage of the internal regulator, VCC. The UVLO rising threshold is about 3.9V while its falling threshold is 3.25V. External Soft-Start Adjust the soft-start time by connecting a capacitor from the SS pin to ground. When the soft-start period starts, an internal 11µA current source charges the external capacitor. The soft- start capacitor connects to the non-inverting input of the error amplifier. The soft-start period lasts until the voltage on the soft-start capacitor exceeds the reference voltage of 0.8V. At this point, the non-inverting amplifier uses the reference voltage. The soft-start time can be calculated as: SS SS 0.8V C (nF) t(ms) 11 A Over-Current-Protection and Hiccup The MP1497S has a cycle-by-cycle over- current limit that protects against the inductor current peak value exceeding the set current |
同様の部品番号 - MP1497S |
|
同様の説明 - MP1497S |
|
|
リンク URL |
プライバシーポリシー |
ALLDATASHEET.JP |
ALLDATASHEETはお客様のビジネスに役立ちますか? [ DONATE ] |
Alldatasheetは | 広告 | お問い合わせ | プライバシーポリシー | リンク交換 | メーカーリスト All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |