Part Number: LD5850, LD5850GS
Function: Boost Controller for LED Backlight
Package: SOP-8 Pin Type
Manufacturer: Leadtrend Technology
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Description
The LD5850 is a wide-input asynchronous current mode boost controller, capable to operate in the range between 9V and 28V and to generate 14V of voltage to the GATE pin of MOSFET to reduce thermal loss. The current mode control architecture enhances transient response and simplifies the loop compensation. The DIM input allows the brightness control for LED Backlight or LED lighting. The Device also features internal slope compensation, input voltage under-voltage lockout, output voltage short circuit protection, cycle-by-cycle current limit and thermal shutdown protection.
Features
Wide Input Range: 9V to 28V Current Mode Control 0.3V LED Feedback Current Sensing Reference Fixed Switching Frequency PWM Dimming Input Internal Slope Compensation Cycle-by-Cycle Current Limit Over Temperature Protection Applications LED TV Backlight LED Monitor Backlight LED lighting Typical Application VIN VOUT RA VCC 124 VCC DRV CS DIM 8 DIM LD5850 FB 5 OVP COMP GND 763 COVP RCS RFB RB Fig. 1 Application circuit Leadtrend Technology Corporation LD5850-DS-00 November 2012 1 www.leadtrend.com.tw Pin Configuration VSOCPC-8 (TOP VIEW) DIM OVP COMP FB 8765 TOP MARK YYWWPP 1 YY2WW3 PP4 YY: Year code WW: Week code PP: Production code LD5850 VCC DRV GND CS Ordering Information Part number Package LD5850 GS SOP-8 The LD5850 is ROHS compliant/ Green Packaged. TOP MARK LD5850 GS Shipping 2500 /tape & reel Pin Descriptions PIN NAME 1 VCC 2 DRV 3 GND 4 CS 5 FB 6 COMP 7 OVP 8 DIM FUNCTION Power source VCC pin. Gate drive output to drive the external MOSFET. Ground. Current Sense pin. Connect with an external current sensing resistor to GND. CS pin voltage is used to provide current feedback in the control loop and detect an overcurrent condition. LED output current feedback through a current sense resistor. Compensation of the error amplifier for voltage loop compensation. Over-voltage protection. PWM Dimming Input. If the DIM pin voltage is below logic Voltage threshold, the DRV control would be stopped immediately until DIM pin voltage rises to high again. Leadtrend Technology Corporation LD5850-DS-00 November 2012 2 www.leadtrend.com.tw Block Diagram DIM OVP 0.2V 2.5V LD5850 VCC DIM SCP 8.7V/7.0V UVLO VCC OK Internal Bias & Vref Vref OK DIM OVP SCP LED SHORT Vref Driver Stage 14V DRV Slope Compensation CS LEB GND Osillator PWM Comparator SQ R 0.5V OCP Comparator Voltage Divider & Buffer LED SHORT 0.3V GM 0.6V COMP FB Leadtrend Technology Corporation LD5850-DS-00 November 2012 3 www.leadtrend.com.tw LD5850 Absolute Maximum Ratings VCC, DRV, CS, FB, OVP All Other Pins Power Dissipation, PD@85C, SOP-8 Package Thermal Resistance, SOP-8, JA Maximum Junction Temperature Operating Junction Temperature Operating Ambient Temperature Storage Temperature Range Lead Temperature (Soldering, 10sec) ESD L […]
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