Features: • Step-down LED driver
• 4V to 18V input voltage range
• Up to 1.5A output current
• Typical efficiency# > 85%
• User-defined thermal control of LED output current using external thermistor
• High output current stability over input voltage and temperature
• 12A typical standby current
• LED current adjustable from 100% down to 2%
• Adjustable soft-start
• Power 'OK' flag output
• Capable of driving 4 LEDs in seriesApplication• Low voltage halogen lamp replacement with LEDs
• High power LED flashlights
• LED back-up lighting
• General LED lighting
• Automotive lightingPinout
Specifications
| Part Number
| ZXLD1320 |
| Min.- Max. Input Voltage (V) |
4 ~ 18 |
| Output Voltage (V) |
18 |
| Typ Peak Output Current (A) |
- |
| Max Output Current (mA) |
1.5 |
| LED Current Accuracy (%) |
5 |
| Frequency (kHz) typ |
600 |
| Efficiency (%) |
85 |
| Operating Temperature (C) |
-40 to +125 |
| Quiescent Current (mA) typ |
1.5 |
| Standby Quiescent Current (uA) typ |
12 |
(Voltages relative to GND unless otherwise stated)
Operating temperature (Top) ..................-40 to 125
Storage temperature (Tst)...................... -55 to 150
Junction temperature (Tj)........................ -40 to 150
Package power dissipation (Ptot)
DFN-14 with Exposed Pad: 4mmx3mm, 0.5mm Pitch 1.5W at Tamb = 70
DC-DC Converter
Supply voltage (VIN) ................................-0.3V to +18V
POK................................................. -0.3V to VIN + 0.3V
ADJ ...........-0.3V to The lower of (+5.0V) or (VIN + 0.3V)
CFB ..........-0.3V to The lower of (+5.0V) or (VIN + 0.3V)
ISENSE..... -0.3V to The lower of (+5.0V) or (VIN + 0.3V)
TADJ......... -0.3V to The lower of (+5.0V) or (VIN + 0.3V)
BIAS......... -0.3V to The lower of (+5.0V) or (VIN + 0.3V)
POK ..........-0.3V to The lower of (+5.0V) or (VIN + 0.3V)
High-Side current monitor
Continuous sense voltage (M_VIN M_LOAD)....-0.3V to +5V
Switching NPN transistor
Collector-Base voltage (VCBO)................................. 20V
Collector-Emitter voltage (VCEO)............................. 20V
Peak pulse current (ICM).............. 3A (Pulse Width = 300s. Duty Cycle<=2%)
Continuous Collector current (IC) ............................1.5A
These are stress ratings only. Operation outside the absolute maximum ratings may cause device failure. Operation at the absolute maximum ratings for extended periods may reduce device reliability.
DescriptionZXLD1320 is an inductive DC-DC converter, with an internal switch, designed for driving single or multiple LEDs in series up to a total of 1.5A output current.Applications cover both commercial and automotive environments with input voltages ranging from 4V to 18V. Depending upon supply voltage and external components, this can provide up to 24W of output power.
The device employs a variable 'on' and 'off' time control scheme with adjustable peak switch current limiting and operates in the step-down (Buck) operating mode, offering higher power efficiency and lower system cost than conventional PFM circuitry.
The device includes the DC-DC converter, a high-side current monitor and an NPN switching transistor to provide an integrated solution offering small PCB size, competitive cost/performance, high power efficiency of DC-DC conversion and maximum LED brightness/reliability. More importantly, it retains design flexibility to add customer specific features. The feedback control circuitry inside the ZXLD1320 provides excellent load and current regulation, resulting in very stable LED current over the full operating voltage and temperature range.
The LED current can be adjusted from 100% down to 10% of the set value by applying a dc voltage to the ADJ pin and down to 1% by applying a PWM signal. An on-chip LED protection circuit also allows output current to be reduced linearly above a predetermined threshold temperature using an external thermistor at the TADJ pin.External resistors set nominal average LED current and coil peak current independently.
The 'Power-OK' (POK) output flag remains high during normal operation, but switches low if the switch transistor remains on for more than 500s. This provides indication of a low battery, or fault condition. The POK output may be used to drive an LED or the input of an MCU.
The device can be shut down by applying a continuous low level dc voltage to the ADJ pin.
ZXLD1320 Data Sheet
