Electronic Components Datasheet Search |
|
MP2105 Datasheet(PDF) 6 Page - Monolithic Power Systems |
|
MP2105 Datasheet(HTML) 6 Page - Monolithic Power Systems |
6 / 8 page MP2105 – 1MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER MP2105 Rev. 1.3 www.MonolithicPower.com 6 5/11/2006 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2006 MPS. All Rights Reserved. TM Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for superior load and line response and protection of the internal main switch and synchronous rectifier. The MP2105 switches at a constant frequency (1MHz) and regulates the output voltage. During each cycle the PWM comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltage. During normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the next cycle starts. Dropout Operation The MP2105 allows the main switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage is dropping close to the output voltage. When the duty cycle reaches 100%, the main switch is held on continuously to deliver current to the output up to the PFET current limit. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. Short Circuit Protection The MP2105 has short circuit protection. When the output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the PFET current limit. The PFET current limit is also reduced to lower the short circuit current. The frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V. Maximum Load Current The MP2105 can operate down to 2.5V input voltage; however the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases. APPLICATION INFORMATION Output Voltage Setting The external resistor divider sets the output voltage (see Figure 3). The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor (see Figure 1). Choose R1 around 500kΩ for optimal transient response. R2 is then given by: 1 V 6 . 0 V 1 R 2 R OUT − = Table 1—Resistor Selection vs. Output Voltage Setting VOUT R1 R2 1.2V 499k Ω (1%) 499k Ω (1%) 1.5V 499k Ω (1%) 332k Ω (1%) 1.8V 499k Ω (1%) 249k Ω (1%) 2.5V 499k Ω (1%) 158k Ω (1%) Inductor Selection A 1µH to 10µH inductor with DC current rating at least 25% higher than the maximum load current is recommended for most applications. For best efficiency, the inductor DC resistance shall be <200mΩ. See Table 2 for recommended inductors and manufacturers. For most designs, the inductance value can be derived from the following equation: () OSC L IN OUT IN OUT f I V V V V L × ∆ × − × = where ∆IL is Inductor Ripple Current. Choose inductor ripple current approximately 30% of the maximum load current, 800mA. The maximum inductor peak current is: 2 I I I L LOAD ) MAX ( L ∆ + = Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. Table 3 lists inductors recommended for this purpose. |
Similar Part No. - MP2105_06 |
|
Similar Description - MP2105_06 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |