Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
CAT4106HV4-GT2 Datasheet(PDF) 11 Page - ON Semiconductor |
|
CAT4106HV4-GT2 Datasheet(HTML) 11 Page - ON Semiconductor |
11 / 15 page CAT4106 http://onsemi.com 11 The external resistor R6 value needed to set a VFMIN level of 18 V is calculated as follows: R6 + R7 18 V 1.2 V * 1 For R7 = 20 k W, R6 = 280 kW. Setting VFMAX Level (Open−LED) The VFMAX level represents the maximum level expected for the LED string voltage “window of operation”. This voltage setting is based on the number of series LEDs being used and the expected maximum VF during normal operation. Example: Consider a string of 6 LEDs in series, with each LED having a VF range of 3.5 V ± 0.5 V. Since the maximum VF of each LED is 4.0 V, the overall maximum expected string voltage would be 24 V. Any string voltage which appears greater than 24 V would be considered as containing an open−circuit in one or more of the series LEDs. The external resistor R4 value needed to set a VFMAX level of 24 V is calculated as follows: R4 + R5 24 V 1.2 V * 1 For R5 = 20 k W, R4 = 380 kW. In normal operation, the LED string which has the largest VF will be used to set the VCTRL/VFB voltage levels. If the largest string voltage tries to exceed VFMAX setting, it will no longer be allowed to control the voltage level of VCTRL/VFB (i.e. it will be ignored) and subsequently the next largest LED string voltage will then be used in the control loop. All remaining functional LED channels will continue to operate as normal. If a disconnected LED string is reconnected, the FAULT flag remains on and the channel disabled until the device has been re−enabled with the EN pin going from low to high. If all LED channels are detected as being open−circuit, then the boost converter will limit the output voltage to the VFMAX setting. This eliminates the need for an external protection zener. Enable and PWM Dimming Control EN/PWM input signal provides two independent functions. The first function is to enable and disable the entire device. The second function is to apply PWM dimming on the output channels while the chip remains fully enabled. Applying logic high on the EN/PWM input will power up the device. The device will continue to remain powered up, even in the presence of PWM signals being applied. To disable the device into complete system shutdown mode, a logic low must be applied to the EN/PWM input for typically 5 ms. The duty cycle applied at the EN/PWM is directly applied to all the output channels. Each time the input is taken low, all output channels will immediately be switched off and the channels will resume normal operation when the PWM is taken back high. The response time of the channels when switching ON or OFF is typically 0.2 ms. During PWM dimming, the recommended minimum pulse width interval (either High or Low) is 0.2 ms. The recommended maximum pulse width during PWM dimming is 2.0 ms, however this only applies to the Low pulse interval. Pulse durations extending past 2.0 ms may cause the device to enter full shutdown mode. The LED channel response time is longer if the device has been in shutdown mode. For most applications, a maximum dimming resolution can be achieved with PWM clock frequencies in the range of 500 Hz to 2 kHz. Pulse width intervals of 1 ms, allows up to 1000:1 dimming ratio at 1 kHz PWM frequency. One or Two LED String Applications The CAT4106 can be used to drive one or two strings of LEDs by connecting together some LED pins. Also for applications requiring LED current greater than 175 mA, LED channels can be tied together, assuming the supply is suitable to drive the load. Figure 27 shows a typical application for driving a single string of LEDs. Note: VFMIN is disabled for one string. Figure 27. Application Circuit for One LED String GND LED2 LED3 LED1 LED4 RSET EN/PWM CAT4106 VIN VFMAX VFMIN C1 SW R1 PGND FB VCTRL R3 R5 R7 R8 LED Fault Detection (open drain pull−down) R4 R6 R2 C2 L D C3 VIN VIN VL FAULT OFF... ON... DIM... Figure 28 shows a typical application for driving two strings of LEDs. The LED current is equal to two times the channel current. Figure 28. Application Circuit for Two LED Strings GND LED2 LED3 LED1 LED4 RSET EN/PWM CAT4106 VIN VFMAX VFMIN C1 SW R1 PGND FB VCTRL R3 R5 R7 R8 LED Fault Detection (open drain pull−down) R4 R6 R2 C2 L D C3 OFF... ON... DIM... FAULT VIN VIN VL |
Número de pieza similar - CAT4106HV4-GT2 |
|
Descripción similar - CAT4106HV4-GT2 |
|
|
Enlace URL |
Política de Privacidad |
ALLDATASHEET.ES |
¿ALLDATASHEET es útil para Ud.? [ DONATE ] |
Todo acerca de Alldatasheet | Publicidad | Contáctenos | Política de Privacidad | Intercambio de Enlaces | Lista de Fabricantes 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 |