RT8452GS Richtek

RT8452 High Voltage High Current LED Driver Controller for Buck Boost or Buck-Boost Topology General Description Features zz z zz High Voltage Capability : V Up to 36V, V Up to IN OUT The RT8452 is a current mode PWM controller designed 48V to drive an external MOSFET for high current LED zz z zz Buck, Boost or Buck-Boost Operation applications. With a current sense amplifier threshold of zz z zz Current Mode PWM with 350kHz Switching 190mV, the LED current is programmable with one Frenquency external current sense resistor. With the maximum zz z zz Easy Dimming Control : Analog or Digital operating input voltage of 36V and output voltage up to Converting to Analog with One External Capacitor 48V, the RT8452 is ideal for Buck, Boost or Buck-Boost zz z zz True PWM Dimming : External FET Driver is Build- operation. in With 350kHz operating frequency, the external inductor zz z zz Programmable Soft Start to Avoid Inrush Current and capacitors can be small while maintaining high zz z zz Programmable Over Voltage Protection efficiency. zz z zz V Undervoltage Lockout and Thermal Shutdown IN Dimming can be done by either analog or digital. A built-in zz z zz 16-Lead WQFN and SOP Packages. clamping comparator and filter allow easy low noise analog zz z zz RoHS Compliant and Halogen Free dimming conversion from digital signal with only one Applications external capacitor. An unique True PWM dimming control is made easy with MOSFET under LED string. A very high z General Industrial High Power LED Lighting dimming ratio can be achieved by adopting both analog/ z Desk Lights and Room Lighting digital dimming and True PWM dimming together. z Building and Street Lighting z Industrial Display Backlight The RT8452 is available in WQFN-16L 3x3 and SOP-16 packages. Pin Configurations (TOP VIEW) Ordering Information GBIAS 16 GND RT8452 2 15 GATE VCC 3 14 Package Type PWMOUT OVP 4 13 ISW EN S : SOP-16 5 12 PWMDIM NC QW : WQFN-16L 3x3 (W-Type) ISP 6 11 SS 7 10 ISN Lead Plating System DCTL 8 9 VC ACTL G : Green (Halogen Free and Pb Free) Note : SOP-16 Richtek products are : ` RoHS compliant and compatible with the current require- 16 15 14 13 ments of IPC/JEDEC J-STD-020. GBIAS 1 12 NC ` Suitable for use in SnPb or Pb-free soldering processes. 2 11 GATE SS GND 3 10 PWMOUT DCTL 17 4 9 ISW ACTL 5 6 7 8 WQFN-16L 3x3 Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8452-03 May 2012 www.richtek.com 1 PWMDIM GND ISP VCC ISN OVP VC ENRT8452 Marking Information RT8452GS RT8452GQW RT8452GS : Product Number F4= : Product Code RT8452 YMDNN : Date Code YMDNN : Date Code F4=YM GSYMDNN DNN Typical Application Circuit L1 R SENSE D1 47H 0.09 V OUT V IN 48V (Max.) C 4.5V to 36V IN C OUT 10F 1F RT8452 M1 15 2 GATE VCC 14 LEDs R SW 0.05 13 4 EN 5V ISW 6 Analog 9 ISP ACTL Dimming 7 ISN 10 DCTL R1 14 OVP V 8 OUT VC 3 PWMOUT R VC 11 R2 SS 10k 5 PWMDIM 1 GBIAS C SS C GND VC 0.1F 3.3nF C B 16, 17 (Exposed Pad) 1F Figure 1. Analog Dimming in Boost Configuration R L1 SENSE D1 47H 0.09 V OUT V IN 48V (Max.) 4.5V to 36V C IN C OUT 10F 1F RT8452 M1 2 15 GATE VCC R 14 LEDs SW 13 0.05 4 EN 5V ISW 10 6 DCTL PWM ISP Dimming control 7 8 ISN VC R1 14 V OVP OUT R VC 11 SS 10k 3 PWMOUT 1 GBIAS R2 C SS 5 C PWMDIM VC 0.1F 9 3.3nF C ACTL B GND 1F 16, 17 (Exposed Pad) C A 0.47F Figure 2. PWM to Analog Dimming in Boost Configuration Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS8452-03 May 2012 2