поискавой системы для электроныых деталей |
|
FAN5608 датащи(PDF) 9 Page - Fairchild Semiconductor |
|
FAN5608 датащи(HTML) 9 Page - Fairchild Semiconductor |
9 / 13 page © 2006 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN5608 Rev. 1.0.5 • 8/8/06 9 decreases due to the resistive loss in the switching power FET. Using L = 3.3μΗ and increasing the load to 12 LED x 20mA (POUT = 800mW) requires VIN > 3.5V to maintain a constant 20mA current through LEDs. An inductance L = 4.7μH ensures proper operation for 2 x 4 white LEDs with regulated 20mA current if VIN > 2.7V. For any lighter load or higher VIN, the inductance may be increased to improve the system efficiency. Application examples are given in Figures 16 - 25. The peak current in the inductor depends on the maximum battery voltage and the inductance, according to the equation: L V S I IN pk max 4 . 1 × = μ EQ 7 which gives the maximum rated current for the inductor. For L =4.7μH and VIN = 4.2V, the inductor saturation current should be at least 1A. Capacitors Selection Low ESR capacitors should be used to minimize the input and output ripple voltage. Use of a CIN > 4.7μF/6.3V and COUT = 4.7μF/25V type X5R/X7R multi- layer ceramic capacitor is recommended. A larger value input capacitor placed as close as possible to FAN5608 may be needed to reduce the input voltage ripple in noise-sensitive applications. An additional LC filter between the battery and the FAN5608 input can help reduce the battery ripple to the level required by a particular application. Driving Higher Current LEDs To increase the LED current range to 50mA, the CH1 and CH2 outputs may be connected, as shown below: A1 B1 B2 INDB INDA GND CH1 CIN DAC Inputs L = 4.7µH 4.7µF 2.7V to 5.5V CH2 A2 Figure 14. Digital Brightness Control A1 VIN INDB INDA GND CH1 CIN VEXT L = 4.7µH 4.7µF 2.7V to 5.5V CH2 A2 Figure 15. Analog Brightness Control The current feeding the string of LEDs is the sum of the currents programmed for each channel in digital or analog mode. Using all four inputs in digital mode, the LED current can be programmed within the 0 to 40mA range, according to the following table: Driving Two Independent Strings of LEDs For best efficiency, the two strings of LEDs driven by the FAN5608 should have close forward voltages. This recommendation is met when the same number and type of LEDs are serially connected in each channel. If the application requires the two channels be significantly unbalanced, an external resistor may be added in series with the shorter string of LEDs to reduce the voltage difference between the two channels and enhance performance. The maximum differential LEDs connected in series to CH1 and CH2 is not recommended to exceed three LEDs. Specific Layout Recommendations The FAN5608 is available in a dual Die Attach Pad (DAP) package. One DAP is connected to GND and another to VOUT, making it unnecessary to provide any external connection to the DAPs. Since the internal power dissipation is low, the 4x4mm MLP package is capable of dissipating maximum power without requiring an extra copper field on the printed circuit board. When viewing the bottom of the dual-DAP device package, two electrically isolated exposed metal islands are visible. The two IND pins should be connected externally. Depending on the application noise sensitivity, an external filter may be required between the battery and the IC input. |
Аналогичный номер детали - FAN5608_06 |
|
Аналогичное описание - FAN5608_06 |
|
|
ссылки URL |
Конфиденциальность |
ALLDATASHEETRU.COM |
Вашему бизинису помогли Аллдатащит? [ DONATE ] |
Что такое Аллдатащит | реклама | контакт | Конфиденциальность | обмен ссыками | поиск по производителю 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 |