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A Product Line of Diodes Incorporated
ZXLD1352
350mA LED driver with internal switch and enhanced PWM dimming range
Description
The ZXLD1352 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 7V and 30V and provides an externally adjustable output current of up to 350mA. Depending upon supply voltage and external components, this can provide up to 8 watts of output power. The ZXLD1352 includes the output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. Output current can be adjusted above, or below the set value, by applying an external control signal to the 'ADJ' pin. The ADJ pin will accept either a DC voltage or a PWM waveform. DC voltages between 0.3V and 2.5V allow adjustment of output current from 25% to 200% of nominal. 1000:1 adjustment of output current is possible using PWM control. Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches the device into a low current standby state. The device is assembled in a TSOT23-5 pin package.
Features
• • • • • • • • • • • • • Simple low parts count Internal 30V NDMOS switch 350mA output current Single pin on/off and brightness control using DC voltage or PWM 1000:1 PWM dimming range Soft-start High efficiency (up to 95%(*)) Wide input voltage range: 7V to 30V 40V transient capability Output shutdown Up to 1MHz switching frequency Inherent open-circuit LED protection Typical 4% output current accuracy
Applications
• • • • • Low voltage halogen replacement LEDs Automotive lighting Low voltage industrial lighting LED back-up lighting Illuminated signs
(*) Using standard external components as specified under electrical characteristics. Efficiency is dependent upon the number of LEDs driven and on external component types and values.
Pin connections
LX 1 GND 2 ADJ 3
TSOT23-5 Top view 4 ISENSE 5
Typical application circuit
D1
ZLLS1000
VIN
VIN (12V - 30V)
Rs 0.33
L1 47H C1 1F
PWM
VIN ADJ
ISENSE
LX
ZXLD1352
GND
GND
Issue 1 - August 2008
© Diodes Incorporated 2008
1
www.zetex.com www.diodes.com
Datasheet pdf - http://www.DataSheet4U.net/
www.DataSheet.co.kr
ZXLD1352
Absolute maximum ratings (voltages to GND unless otherwise stated)
Input voltage (VIN) ISENSE voltage (VSENSE) LX output voltage (VLX) Adjust pin input voltage (VADJ) Switch output current (ILX) Power dissipation (Ptot) (Refer to package thermal de-rating curve on page 18) Operating temperature (TOP) Storage temperature (TST) Junction temperature (Tj MAX) -0.3V to +30V (40V for 0.5 sec) +0.3V to -5V (measured with respect to VIN) -0.3V to +30V (40V for 0.5 sec) -0.3V to +6V 500mA 450mW -40 to 105°C -55 to 150°C 150°C
These are stress ratings only. Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability.
Thermal resistance
Junction to ambient (R⍜JA) Symbol
VIN VSU IINQoff IINQon VSENSE
200°C/W
Electrical characteristics (test conditions: VIN=12V, Tamb=25°C unless otherwise stated) (*)
Parameter
Input voltage Internal regulator start-up threshold VIN rising Quiescent supply current with output off Quiescent supply current with output switching Mean current sense threshold voltage (defines LED current setting accuracy) ADJ pin grounded 20 ADJ pin floating f=250kHz Measured on ISENSE pin with respect to VIN VADJ =1.25V 95 250 100 30 500 105 µA µA mV
Conditions
Min.
7
Typ.
4.8
Max.
30
Unit
V V
VSENSEHYS Sense threshold hysteresis ISENSE VREF ⌬VREF /⌬T VADJ VADJoff ISENSE pin input current Internal reference voltage Temperature coefficient of VREF External control voltage range on ADJ pin for dc brightness control (†) DC voltage on ADJ pin to switch device from active (on) state to quiescent (off) state DC voltage on ADJ pin to switch device from quiescent (off) state to active (on) state Resistance between ADJ pin and VREF Continuous LX switch current LX Switch ‘On’ resistance LX switch leakage current VADJ falling 0.3 0.15 VSENSE =VIN -0.1 Measured on ADJ pin with pin floating 1.21
±15 1.25 1.25 50 2.5 0.2 0.25 10 1.29
% µA V ppm/°C V V
VADJon
VADJ rising
0.2
0.25
0.3
V
RADJ ILXmean RLX ILX(leak)
35
65 0.37 1.5 2 1
k⍀ A
⍀
µA
Issue 1 - August 2008
© Diodes Incorporated 2008
2
www.zetex.com www.diodes.com
Datasheet pdf - http://www.DataSheet4U.net/
www.DataSheet.co.kr
ZXLD1352
Electrical characteristics (test conditions: VIN=12V, Tamb=25°C unless otherwise stated) (*) (continued)
Symbol
DPWM(LF)
Parameter
Duty cycle range of PWM signal applied to ADJ pin during PWM dimming mode Brightness control range
Conditions
PWM frequency 100Hz - 1KHz PWM amplitude= VREF Measured on ADJ pin
Min.
0.01
Typ.
Max.
1
Unit
1000:1 ADJ pin floating L=100µH (0.82⍀).