ZXLD1360
1A LED driver with internal switch Description
The ZXLD1360 is a continuous mode inductive step-down converter, designed for driving single or multiple ries 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 1A. Depending upon supply voltage and external components, this can provide up to 24 watts of output power.
The ZXLD1360 includes the output switch and a high-side output current nsing circuit, which us an external resistor to t the nominal average output current.
Output current can be adjusted above, or below the t value, by applying an external control signal to the 'ADJ' pin.The ADJ pin will accept either a DC voltage or a PWM waveform. Depending upon the control frequency, this will provide either a continuous or a gated output current. The PWM filter components are contained within the chip.
The PWM filter provides a soft-start feature by controlling the ri of input/output current. The soft-start time can be incread using an external capacitor from the ADJ pin to ground. 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.
Features
•Simple low parts count
•Internal 30V NDMOS switch
•1A output current
•Single pin on/off and brightness control using DC voltage or PWM
•Internal PWM filter
•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
Pin connections
Typical application circuit
Absolute maximum ratings (voltages to GND unless otherwi stated)Electrical characteristics (test conditions: V IN =12V, T amb =25°C unless otherwi stated)(a)
NOTES:
(a)Production testing of the device is performed at 25°C. Functional operation of the device and parameters specified over a -40°C to +105°C temperature range, are guaranteed by design, characterization and process control.
(b)100% brightness corresponds to V ADJ = V ADJ(nom) = V REF . Driving the ADJ pin above V RE
F will increa the V SENSE .threshold and output current proportionally.
Input voltage (V IN )
-0.3V to +30V (40V for 0.5 c)
I SENSE voltage (V SENSE )+0.3V to -5V (measured with respect to V IN )LX output voltage (V LX )
-0.3V to +30V (40V for 0.5 c)Adjust pin input voltage (V ADJ )-0.3V to +6V Switch output current (I LX ) 1.25A Power dissipation (P tot )
(Refer to package thermal de-rating curve on page 16)
1W
Operating temperature (T OP )-40 to 125°C Storage temperature (T ST )-55 to 150°C Junction temperature (T j MAX )
150°C
The are stress ratings only. Operation outside the absolute maximum ratings may cau device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability.
Thermal resistance
Junction to ambient (R ⍜JA )125°C/W
Symbol Parameter Conditions
Min.Typ.Max.Unit V IN Input voltage
7
30
V V SU Internal regulator start-up threshold V IN rising 5.65V V SD Internal regulator shutdown threshold
V IN falling 5.55
V
I INQoff Quiescent supply current with output off ADJ pin grounded 2040A I INQon Quiescent supply current with output switching ADJ pin floating f = 250kHz 1.8 5.0mA V SENSE
Mean current n threshold voltage (Defines LED current tting accuracy)Measured on I SENSE pin with respect to V IN V
ADJ = 1.25V 95
100
105
mV
V SENSEHYS Sen threshold hysteresis ±15%I SENSE I SENSE pin input current V SENSE = V IN -0.1 1.2510
A V REF
Internal reference voltage
Measured on ADJ pin with pin floating
1.25V ⌬V REF /⌬T Temperature coefficient of V REF 50
ppm/K V ADJ External control voltage range on ADJ pin for DC brightness control (b)0.3
2.5V 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
0.25V
V ADJon DC voltage on ADJ pin to switch device from quiescent (off) state to active (on) state
V ADJ rising
0.20.250.3V
Electrical characteristics (test conditions: V IN =12V, T amb =25°C unless otherwi stated) (cont.)
Symbol Parameter Conditions Min.Typ.
Max.Unit R ADJ Resistance between ADJ pin and V REF 0< V ADJ < V REF V ADJ > V REF +100mV 13513.5
25025k ⍀I LXmean Continuous LX switch current 1A R LX LX Switch ‘On’ resistance @ I LX = 1 A
0.5
1.0⍀I LX(leak)
LX switch leakage current
5A
D PWM(LF)Duty cycle range of PWM signal
applied to ADJ pin during low frequency PWM dimming mode PWM frequency
<500Hz
PWM amplitude = V REF Measured on ADJ pin 0.01
1
Brightness control range
100:1D PWM(HF)Duty cycle range of PWM signal
applied to ADJ pin during high frequency PWM dimming mode PWM frequency >10kHz PWM amplitude = V REF Measured on ADJ pin 0.16
1
Brightness control range
5:1
T SS Soft start time
Time taken for output current to reach 90% of final value after voltage on ADJ pin has rin above 0.3V
500
s
f LX
Operating frequency
(See graphs for more detail)
ADJ pin floating L = 33H (0.093⍀)
I OUT = 1A @ V LED = 3.6V Driving 1 LED 280KHz T ONmin Minimum switch ‘ON’ time LX switch ‘ON’240 (*)NOTES:
(*)Parameters are not tested at production. Parameters are guaranteed by design, characterization and process control.
ns T OFFmin
Minimum switch ‘OFF’ time
LX switch ‘OFF’
200 (*)ns T ONmin_REC Recommended minimum switch 'ON' time
LX switch 'ON'
800
ns f LXmax Recommended maximum
operating frequency
1
MHz
D LX
Recommended duty cycle range of output switch at f LXmax 0.3
0.7
T PD
Internal comparator propagation delay
50
ns
Pin description
Ordering information
Name Pin no.Description
LX 1Drain of NDMOS switch GND 2Ground (0V)
ADJ
3
Multi-function On/Off and brightness control pin:
•Leave floating for normal operation.(V ADJ = V REF = 1.25V giving nominal average output current I OUTnom = 0.1/RS)
•Drive to voltage below 0.2V to turn off output current
•Drive with DC voltage (0.3V < V ADJ < 2.5V) to adjust output current from 25% to 200% of I OUTnom
•Drive with PWM signal from open-collector or open-drain transistor, to adjust output current. Adjust
ment range 25% to 100% of I OUT nom for f>10kHz and 1% to 100% of I OUT nom for f < 500Hz
•Connect a capacitor from this pin to ground to increa soft-start time. (Default soft-start time = 0.5ms. Additional soft-start time is approx.0.5ms/nF)I SENSE
4
Connect resistor R S from this pin to V IN to define nominal average output current I OUT nom = 0.1/R S
(Note: R SMIN = 0.1⍀ with ADJ pin open-circuit)
V IN
5
Input voltage (7V to 30V). Decouple to ground with 4.7F or higher X7R ceramic capacitor clo to device
Device
Reel size (mm)Reel width (inches)
Quantity per reel Device mark ZXLD1360ET5TA
180
8
3,000
1360
Block diagram
