Electronic Components Datasheet Search |
|
RT8494GS Datasheet(PDF) 5 Page - Richtek Technology Corporation |
|
RT8494GS Datasheet(HTML) 5 Page - Richtek Technology Corporation |
5 / 17 page RT8494 5 DS8494-01 November 2015 www.richtek.com © Copyright 2015 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. Operation The startup voltage of the RT8494 is around 4.5V. When VCC voltage is greater than 4.5V, the RT8494 starts operation and a regulated GBIAS supply voltage is generated by an internal LDO circuit. With VCC greater than 10V, the GBIAS supply will be regulated around 8.5V to supply the power for the internal GATE pin driver circuit. As the system starts, the capacitor at the soft-start pin is slowly charged by an internal current source around 6 μA. During soft-start period, the VC pin voltage follows the soft-start pin voltage up by one VBE and gradually ramps up. The slowly rising VC pin voltage allows the PWM duty to increase gradually to achieve soft-start function. In normal operation, the GATE turns high when the oscillator (OSC) turns high. The ISW pin voltage is the triangular feedback signal of the sensed switch current (which equals inductor current ramp). The PWM comparator compares the ISW pin voltage to the VC pin voltage. When the ISW pin voltage exceeds the VC pin voltage, the PWM comparator resets the latch and turns off GATE. If the ISW pin voltage does not exceed the VC pin voltage by the end of the switching cycle, the GATE will be turned off by the OSC circuit for a minimum off time. The cycle repeats when the GATE is turned on at the beginning of the next OSC cycle. The RT8494 features high voltage LED driver control. The common mode operation voltage of the ISP and ISN pins can be high up to 90V. The regulated (VISP − VISN) sense threshold voltage is around 190mV. If the sensed (VISP − VISN) voltage is lower than 190mV, the VC pin will be charged higher by the internal OP AMP in the PWM control loop and vice versa. By the PWM closed loop control, the (VISP − VISN) voltage is regulated to 190mV. The actual LED output current can be adjusted by the sense resistor between the ISP and ISN pins. The dimming can be done by varying the ACTL/DCTL pin voltage signal. The internal sense threshold reference for (VISP − VISN) regulation follows the ACTL/DCTL signal to achieve dimming control. The fault protection features of the RT8494 include (1) VCC Under-Voltage Lockout (UVLO) (2) VOUT Over - Voltage Protection (OVP) (3) switch Over-Current Protection (OCP) (4) Over-Temperature Protection (OTP). |
Similar Part No. - RT8494GS |
|
Similar Description - RT8494GS |
|
|
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 |