Electronic Components Datasheet Search |
|
MP24894 Datasheet(PDF) 10 Page - Monolithic Power Systems |
|
MP24894 Datasheet(HTML) 10 Page - Monolithic Power Systems |
10 / 12 page MP24894 – STEP-DOWN LED-CURRENT CONTROLLER WITH WIDE 6V TO 60V INPUT VOLTAGE MP24894 Rev 1.01 www.MonolithicPower.com 10 12/20/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. APPLICATION INFORMATION Setting the LED Current The LED current is identical and set by the current sense resistor between the IN pin and RS pin. RSENSE=200mV/ILED For RSENSE=0.2Ω, the LED current is set to 1A Selecting the Inductor Lower value of inductance can result in a higher switching frequency, which causes a larger switching loss. Choose a switch frequency between 100kHz to 600kHz for most application. According to switching frequency, inductor value can be estimated as: OUT OUT IN LED SW V (1- ) V V L 0.3 I f × = ×× For higher efficiency, choose an inductor with a DC resistance as small as possible. Selecting the Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. Choose a capacitor value between 10µF and 22µF for most applications. The voltage rating should be greater than the input voltage. Use a low ESR capacitor for input decoupling. Selecting the Output Capacitor For most applications, the output capacitor is not necessary. For applications that require that the peak-to-peak LED ripple current falls below 30% of the average current, add a capacitor across the LEDs. Higher capacitor values will result in proportionally lower ripple. A value of 2.2µF will meet most requirements. Selecting Soft-Start Capacitor When selecting a soft-start capacitor, the delay time can be estimated as 0.2ms/nF. For PWM dimming, select C < 2.2nF to eliminate its effect on the average LED current. Dimming Control MP24894 provides 1:2500 high-ratio PWM dimming. Apply a 100Hz to 20kHz square waveform to the EN/DIM pin. The average LED current is proportional to PWM duty cycle. Layout Consideration Pay careful attention to the PCB layout and component placement. RSENSE should be placed close to the IN pin and RS pin in order to minimize current sense error. The input loop—including input capacitor, Schottky diode, and Mosfet —should be as short as possible. Design Example Below is a design example following the application guidelines for the specifications: Table 1: Design Example VIN 24V VOUT 10V Iout 1A The detailed application schematic is shown in Figure 2. The typical performance and circuit waveforms have been shown in the Typical Performance Characteristics section. For more device applications, please refer to the related Evaluation Board Datasheets. |
Similar Part No. - MP24894 |
|
Similar Description - MP24894 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |