Document
LD7860
12/30/2009
1A High-Brightness LED Driver with Integrated NMOS Switch
REV:00
General Description
The LD7860 is a controller for step-down converters, operating in continuous conduction mode and ideally for driving high brightness of power LEDs. The device operates with inputs from 6V to 30V and utilizes an external high-side current sense resistor to set the normal average output current of up to 1A. Depending on the selection of input voltage and external components, it can drive up to 7pcs of WLEDs (VF=3.5V). Output current can be adjusted below the set value, by applying an external analog or PWM control signal to DIM pin. The device can operate with the switching frequency of up to 1MHz, making it ideal for the applications requiring small footprint and low value external inductors. Some additional features include under-voltage lockout, over current protection and thermal shutdown.
Features
z Wide input voltage range: 6V to 30V z Integrated with 30V NMOS switch z Up to 1A output current z Hysteretic Control z Output current accuracy for ±5% (typ.) z Up to 1MHz switching frequency z Brightness control using analog or PWM signal z High efficiency z Over current protection z Over temperature protection z Inherent open-circuit LED protection z Output shutdown
Applications
z MR16 or LED bulbs z Architectural, Ambient and Low-voltage industrial
lightings z LED replacement for Low-voltage halogen z General lighting applications z Indicators or emergency lighting z LED back-up lighting
Leadtrend Technology Corporation
LD7860-DS-00 December 2009
1
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Typical Application
LD7860
Fig. 1 Typical application circuit
Pin Configuration
MSOP-8 (TOP VIEW)
8 76 5
78 60G K YYWWPP
GND NC DIM NC
TSOT23-5 (TOP VIEW)
VCC
CS
5 60 YWS PP
12
4 3
NC LX VCC CS
1 23 4
LX GN D DIM
S 60: Y, YY: W, WW: P, PP:
LD78 60 Year code Week code Production code
Ordering Information
Part number
Package
TOP MARK
LD7860 GL
TSOT23-5
LD7860 GK
MSOP-8
LD7860 GJ
SOT89-5
The LD7860 is Green Packaged.
YWS/60 7860GK 7860GJ
SOT89-5 (TOP VIEW) CS VCC
5 7 860G J
YYWWPP
12
4 3
DIM GND
LX
Shipping 3000 /tape & reel 2500 /tape & reel 1000 /tape & reel
Leadtrend Technology Corporation
LD7860-DS-00 December 2009
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Pin Descriptions:
MSOP-8
PIN 1 2
NAME NC LX
3 VCC
4 CS 5 NC
6 DIM
7 NC 8 GND
LD7860
FUNCTION No connection. Drain of NMOS switch Input voltage (from 6V to 30V). Bypass this pin with a 4.7μF of ceramic capacitor or larger one to GND. Connect a current sense resistor, RS between this pin and VCC pin to set average LED current ILEDAVG(A)=0.1(V)/RS(Ω) with DIM pin floating. No connection. z Remain floating during normal operation. (VDIM=5V) z Dimming can be accomplished by analog or by PWM control,
depending on the desired applications. z If VDIM is below 0.35V, IC will be disabled. z Connect a capacitor from it to GND to set the soft-start time. Connect a current sense resistor between it and VCC pin to set average LED current ILEDAVG(A)=0.1(V)/RS(Ω) with DIM pin floating. IC GND.
TSOT23-5
PIN 1 2
3
4 5
NAME LX
GND
DIM
CS VCC
FUNCTION Drain of NMOS switch IC GND. z Remain floating during normal operation. (VDIM=5V) z Dimming can be accomplished by analog or by PWM control,
depending on the desired applications. z If VDIM is below 0.35V, IC will be disabled. z Connect a capacitor from it to GND to set the soft-start time. Connect a current sense resistor between it and VCC pin to set average LED current ILEDAVG(A)=0.1(V)/RS(Ω) with DIM pin floating. Input voltage (from 6V to 30V). Bypass this pin with a 4.7μF of ceramic capacitor or larger one to GND.
Leadtrend Technology Corporation
LD7860-DS-00 December 2009
3
www.leadtrend.com.tw
SOT89-5
PIN
1
2 3 4 5
LD7860
NAME
DIM
GND LX VCC CS
FUNCTION z Remain floating during normal operation. (VDIM=5V) z Dimming can be accomplished by analog or by PWM control,
depending on the desired applications. z If VDIM is below 0.35V, IC will be disabled. z Connect a capacitor from it to GND to set the soft-start time. IC GND. Drain of NMOS switch Input voltage (from 6V to 30V). Bypass this pin with a 4.7μF of ceramic capacitor or larger one to GND. Connect a current sense resistor between it and VCC pin to set average LED current ILEDAVG(A)=0.1(V)/RS(Ω) with DIM pin floating.
Block Diagram
Leadtrend Technology Corporation
LD7860-DS-00 December 2009
4
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LD7860
Absolute Maximum Ratings
VCC and CS Pin to GND LX Pin to GND LX Current DIM Pin to GND Power dissipation TSOT-25@Ta=25°C Package Thermal Resistance TSOT-25 Power dissipation SOT89-5@Ta=25°C Package Thermal Resistance SOT89-5 Power dissipation MSOP-8@Ta=25°C Package Thermal Resistance MSOP-8 Operating Ambient Temperature Range Storage Temperature Range Maximum Operating Junction Temperature Lead Temperature (Soldering, 10sec) ESD Level (Human Body Model) ESD Level (Machine Model)
-0.3V~32V (33V for 0.5s) -0.3V~33V (34V for 0.5s) 3.5A -0.3V~6V 45.