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PDF ZXLD1350 Data sheet ( Hoja de datos )
| Número de pieza | ZXLD1350 | |
| Descripción | 30V 350mA LED DRIVER | |
| Fabricantes | Diodes | |
| Logotipo |  |
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A Product Line of
Diodes Incorporated
ZXLD1350
30V 350mA LED DRIVER with AEC-Q100
Description
The ZXLD1350 is a hysteretic mode inductive step-down
converter with integrated switch and high side current sense.
It operates from an input supply from 7V to 30V driving single
or multiple series connected LEDs efficiently external
adjustable output current up to 350mA.
The ZXLD1350 has been qualified to AECQ100 grade 2
allowing it to operate at ambient temperatures from -40 to
105°C.
The output current can be adjusted by applying a DC voltage
or a PWM waveform. 100:1 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.
Pin Assignments
LX
GND
ADJ
TSOT23-5
Top View
VIN
ISENSE
Features
Typical Application Circuit
• Simple low parts count
• Internal 30V NDMOS switch
• Internal PWM filter
• High efficiency (up to 95% (Note 1)
• Wide input voltage range: 7V to 30V
• 40V transient capability
• Up to 1MHz switching frequency
• Typical 4% output current accuracy
• Qualified to AEC-Q100 Grade 2
• Available in “Green” Molding Compound (No Br, Sb)
• Lead Free Finish/ RoHS Compliant (Note 2)
VIN
7~30V
C1
1µF
GND
RS
0.33Ω
L1
47µH
VIN SET
ADJ ZXLD1350
GND
LX
Notes: 1. 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.
2. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at:
http://www.diodes.com/products/lead_free.html
ZXLD1350
Document number: DS33468 Rev. 8 - 2
1 of 22
www.diodes.com
March 2011
© Diodes Incorporated
1 page  
Device Description
A Product Line of
Diodes Incorporated
ZXLD1350
30V 350mA LED DRIVER with AEC-Q100
The device, in conjunction with the coil (L1) and current sense resistor (RS), forms a self-oscillating continuous-mode buck
converter.
Device operation (Refer to block diagram and Figure 1 - Operating waveforms)
Operation can be best understood by assuming that the ADJ pin of the device is unconnected and the voltage on this pin
(VADJ) appears directly at the (+) input of the comparator.
When input voltage VIN is first applied, the initial current in L1 and RS is zero and there is no output from the current sense
circuit. Under this condition, the (-) input to the comparator is at ground and its output 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 (VSENSE) across RS. The supply referred voltage VSENSE is forced across internal
resistor R1 by the current sense circuit and produces a proportional current in internal resistors R2 and R3. This produces a
ground referred rising voltage at the (-) input of the comparator. When this reaches the threshold voltage (VADJ), the
comparator output switches low and MN turns off. The comparator output also drives another NMOS switch, which bypasses
internal resistor R3 to provide a controlled amount of hysteresis. The hysteresis is set by R3 to be nominally 15% of VADJ.
When MN is off, the current in L1 continues to flow via D1 and the LED(s) back to VIN. The current decays at a rate
determined by the LED and diode forward voltages to produce a falling voltage at the input of the comparator. When this
voltage returns to VADJ, the comparator output switches high again. This cycle of events repeats, with the comparator input
ramping between limits of VADJ ± 15%.
Switching thresholds
With VADJ =VREF, the ratios of R1, R2 and R3, define an average VSENSE switching threshold of 100mV (measured on the
ISENSE pin with respect to VIN). The average output current IOUTnom is then defined by this voltage and Rs according to:
IOUTnom=100mV/RS
Nominal ripple current is ±15mV/RS
Adjusting output current
The device contains a low pass filter between the ADJ pin and the threshold comparator and an internal current limiting
resistor (200k nom) between ADJ and the internal reference voltage. This allows the ADJ pin to be overdriven with either
DC or pulse signals to change the VSENSE switching threshold and adjust the output current. The filter is third order,
comprising three sections, each with a cut-off frequency of nominally 4kHz.
Details of the different modes of adjusting output current are given in the applications section.
Output shutdown
The output of the low pass filter drives the shutdown circuit. When the input voltage to this circuit falls below the threshold
(0.2V nom), the internal regulator and the output switch are turned off. The voltage reference remains powered during
shutdown to provide the bias current for the shutdown circuit. Quiescent supply current during shutdown is nominally
15mA and switch leakage is below 1mA.
ZXLD1350
Document number: DS33468 Rev. 8 - 2
5 of 22
www.diodes.com
March 2011
© Diodes Incorporated
5 Page 
Typical Characteristics (Continued)
A Product Line of
Diodes Incorporated
ZXLD1350
30V 350mA LED DRIVER with AEC-Q100
ZXLD1350
Document number: DS33468 Rev. 8 - 2
11 of 22
www.diodes.com
March 2011
© Diodes Incorporated
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet ZXLD1350.PDF ] | |
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