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ZXLD1362ET5TA

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P25
ZXLD1362
Document number: DS33472 Rev. 6 - 2
4 of 25
www.diodes.com
March 2014
© Diodes Incorporated
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Product Line o
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Diodes Incorporated
ZXLD1362
Electrical Characteristics (@ V
IN
= 24V, T
A
= +25°C, unless otherwise specified.)
Symbol Parameter Condition Min Typ Max Unit
V
SU
Internal regulator start-up threshold 4.85 V
V
SD
Internal regulator shutdown threshold 4.75 V
I
INQoff
Quiescent supply current with output off ADJ pin grounded 65 90 µA
I
INQon
Quiescent supply current with output switching
(Note 9)
ADJ pin floating, L = 68µH,
3 LEDs, f = 260kHz
1.8 mA
V
SENSE
Mean current sense threshold voltage
(Defines LED current setting accuracy)
Measured on I
SENSE
pin with
respect to V
IN
V
ADJ
= 1.25V
95 100 105 mV
V
SENSEHYS
Sense threshold hysteresis ±10 %
I
SENSE
I
SENSE
pin input current V
SENSE
= V
IN
-0.1
4 10 µA
V
REF
Internal reference voltage
Measured on ADJ pin with
pin floating
1.25 V
ΔV
REF
/ΔT Temperature coefficient of V
REF
50 ppm/°C
V
ADJ
External control voltage range on ADJ pin for DC
brightness control (Note 7)
0.3 2.5 V
V
ADJoff
DC voltage on ADJ pin to switch device from active
(on) state to quiescent (off) state
V
ADJ
falling
0.15 0.2 0.27 V
V
ADJon
DC voltage on ADJ pin to switch device from
quiescent (off) state to active (on) state
V
ADJ
rising
0.2 0.25 0.3 V
R
ADJ
Resistance between ADJ pin and V
REF
0 < V
ADJ
< V
REF
V
ADJ
> V
REF
+100mV
30
10.4
50
14.2
65
18
k
I
LXmean
Continuous LX switch current 1 A
R
LX
LX switch ‘On’ resistance
@ I
LX
= 1A
0.5 1.0
I
LX(leak)
LX switch leakage current 5 µA
D
PWM(LF)
Duty cycle range of PWM signal applied to ADJ pin
during low frequency PWM dimming mode
PWM frequency <300Hz
PWM amplitude = V
REF
Measured on ADJ pin
0.001 1
Brightness control range 1000:1
DC
ADJ
DC Brightness control range Note 10 5:1
t
SS
Soft start time
Time taken for output current
to reach 90% of final value
after voltage on ADJ pin has
risen above 0.3V. Requires
external capacitor 22nF. See
graphs for more details
2 ms
f
LX
Operating frequency
(See graphs for more details)
ADJ pin floating
L = 68µH (0.1V)
I
OUT
= 1A @ V
LED
= 3.6V
Driving 3 LEDs
300 kHz
t
ONmin
Minimum switch ‘ON’ time LX switch ‘ON’ 130 ns
t
OFFmin
Minimum switch ‘OFF’ time LX switch ‘OFF’ 70 ns
Notes: 9. Static current of device is approximately 700µA, see Graph, Page 16.
10. Ratio of maximum brightness to minimum brightness before shutdown V
REF
= 1.25/0.3. V
REF
externally driven to 2.5V, ratio 10:1.
ZXLD1362
Document number: DS33472 Rev. 6 - 2
5 of 25
www.diodes.com
March 2014
© Diodes Incorporated
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Product Line o
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Diodes Incorporated
ZXLD1362
Device Description
The device, in conjunction with the coil (L1) and current sense resistor (R
S
), forms a self-oscillating continuous-mode buck converter.
Device operation (refer to Figure 1 - Block diagram and Figure 2 Operating waveforms)
Figure 2 Theoretical Operating Waveforms
Operation can be best understood by assuming that the ADJ pin of the device is unconnected and the voltage on this pin (V
ADJ
) appears directly
at the (+) input of the comparator.
When input voltage V
IN
is first applied, the initial current in L1 and R
S
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 V
IN
to ground, via R
S
, L1 and the LED(s). The current rises at a rate determined by V
IN
and L1 to produce a voltage ramp (V
SENSE
) across
R
S
. The supply referred voltage V
SENSE
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 (V
ADJ
), 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 10% of V
ADJ
.
When MN is off, the current in L1 continues to flow via D1 and the LED(s) back to V
IN
. The current decays at a rate determined by the LED(s)
and diode forward voltages to produce a falling voltage at the input of the comparator. When this voltage returns to V
ADJ
, the comparator output
switches high again. This cycle of events repeats, with the comparator input ramping between limits of V
ADJ
± 10%.
ZXLD1362
Document number: DS33472 Rev. 6 - 2
6 of 25
www.diodes.com
March 2014
© Diodes Incorporated
A
Product Line o
f
Diodes Incorporated
ZXLD1362
Device Description (cont.)
Switching Thresholds
With V
ADJ
= V
REF
, the ratios of R1, R2 and R3 define an average V
SENSE
switching threshold of 100mV (measured on the I
SENSE
pin with respect
to V
IN
). The average output current I
OUTnom
is then defined by this voltage and R
S
according to:
I
OUTnom
= 100mV/R
S
Nominal ripple current is ±10mV/R
S
Adjusting output current
The device contains a low pass filter between the ADJ pin and the threshold comparator and an internal current limiting resistor (50k 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 V
SENSE
switching threshold and adjust the output current.
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 60A and switch leakage is below 5A.
Actual Operating Waveforms
V
IN
= 15V, R
S
= 0.1V, L = 100µH Normal operation.
Output Current (Ch1) and LX Voltage (Ch2)
V
IN
= 30V, R
S
= 0.1V, L = 100µH Normal Operation.
Output Current (Ch1) and LX Voltage (Ch2)
V
IN
= 60V, R
S
= 0.1V, L = 100µH Normal Operation.
Output Current (Ch1) and LX Voltage (Ch2)
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ZXLD1362ET5TA

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Buy ZXLD1362ET5TA
Manufacturer:
Diodes Incorporated
Description:
LED Lighting Drivers 1A/60V LED DRIVER
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