CL6807 查看數據表（PDF） - Unspecified

零件编号

产品描述 (功能)

比赛名单

CL6807

30V 1A LED driver with internal switch

Unspecified 

CHIPLINK

SEMICONDUCTOR

SIMPLIFIED BLOCK DIAGRAM

CL6807

VIN

ISNS

ADJ

REGULATOR

BANDGAP

REF

-

+

Current Sense

COMPARATOR

1.25V

+

-

UVLO

COMPARATOR

DRIVER

LOGIC

ADJ

BUFFER

LX

GND

OPERATION DESCRIPTION

The CL6807 are step-down, constant current,high-brightness LED (HB LED) drivers. These

devices operate from a 7V to 30V input voltage range and provide up to 1A souring LEDs. A

highside current-sense resistor sets the output current and a dedicated PWM dimming input (ADJ)

allows for a wide range of independent pulsed dimming. The high-side current-sensing scheme and

on-board current-setting circuitry minimize the number of external components while delivering LED

current with a ±5% accuracy, using a 1% sense resistor. The device, in conjunction with the coil

(L1) and current sense resistor (RS), forms a self oscillating continuous-mode buck converter.

When input voltage VIN is first applied, the initial current in L1 and RS is zero and there is no

output fromthe current sense circuit. Under this condition, the output of CS comparator is high. This

turns MN on and switches the LX pin low, causing current to flow from VIN to ground, via RS, L1 and

the LED(s). The current rises at a rate determined by VIN and L1 to produce a voltage ramp (VISNS)

across RS. When (VIN-VISNS) >115mV, the output of CS comparator switches low and MN turns off.

The current flowing on the RS decreases at another rate. When (VIN-VISNS) < 85mV, the MN turns

on again and the mean current on the LED is determined by ((85+ 115)/2 mV) / RS = 100mV / RS .

The high-side current-sensing scheme and on-boardcurrent-setting circuitry minimize the

number of external components while delivering LED current with ±5% accuracy, using a 1% sense

resistor.

The CL6807 allow dimming with a PWM signal at the ADJ input. A logic level below 0.3V at ADJ

forces CL6807 to turn off the LED and the logic level at ADJ must be at least 2.5V to turn on the

2008-09-09

4

http://www.chiplink-semi.com

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