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Diodes Incorporated ZXLD1321DCATC
- Part No.:
- ZXLD1321DCATC
- Manufacturer:
- Diodes Incorporated
- Category:
- LED Drivers
- Package:
- 14-UFDFN Exposed Pad
- Datasheet:
-
ZXLD1321DCATC.pdf
- Description:
- IC LED DRIVER RGLTR PWM 1A 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,667
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Product details
Overview
ZXLD1321DCATC from Diodes Incorporated (formerly Zetex Semiconductors) is a boost-mode DC-DC LED driver IC with integrated 2A NPN switch, high-side current monitor, and thermal compensation interface. It delivers up to 1A constant LED current from 1.2V–12V input, supports PWM/dim control via ADJ pin, and operates in bootstrap mode down to 1V input. Used in high-power flashlight and emergency lighting systems requiring stable current regulation across temperature and battery discharge.
For engineers reviewing the ZXLD1321DCATC datasheet, ZXLD1321DCATC pinout, ZXLD1321DCATC application, or ZXLD1321DCATC equivalent, key selection criteria include adjustable peak switch current (via ISENSE), thermal foldback using external NTC at TADJ, 50mV nominal VSENSE threshold, 12µA standby current, and DFN14 4mm×3mm package with exposed thermal pad.
Technical Context
The ZXLD1321 employs a variable on/off time PFM control architecture where the error voltage on CFB modulates the ISENSE reset threshold to regulate coil energy per cycle. Its dual-mode operation-normal PFM above 2.2V VIN and fixed-frequency start-up oscillator below 1.8V-enables reliable single-cell alkaline or NiMH operation.
Internal circuitry integrates three functional blocks: a 2A/18V NPN switching transistor with 50mV ±10mV VSENSE sense threshold, a high-side current monitor with 100mV full-scale VMON and ±3% accuracy, and a thermally compensated current sink referenced to TADJ's 75mV/50mV hysteresis thresholds for linear LED current reduction.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.2V–12V: Enables direct operation from single-cell batteries (1.2V–1.5V) through 12V automotive rails. |
| Max Output Current | 1A continuous LED current: Sufficient to drive 5× white LEDs (3.2V each) in series at full brightness. |
| VSENSE Threshold | 50mV ±10mV: Sets peak switch current as ISWPEAK = 50mV / RSENSE; defines overcurrent protection point. |
| Standby Current | 12µA typical: Achieved by grounding ADJ pin; enables ultra-low-power battery backup mode. |
| Thermal Foldback Threshold | TADJ upper/lower thresholds = 75mV / 50mV: Linearly reduces LED current from 100% to 0% as thermistor network pulls TADJ below 75mV. |
| Efficiency | Typical >85%: Measured at ILED=350mA–1A; dependent on external coil selection and PCB layout. |
| Package Thermal Resistance | RθJC = 26.3°C/W: Requires exposed pad soldered to PCB copper for 1.5W power dissipation at TA=70°C. |
Pinout & Package
ZXLD1321DCATC uses a 14-pin DFN package (4mm × 3mm, 0.5mm pitch) with exposed thermal pad (Pin 15) that must be connected to ground for thermal performance and electrical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ADJ (1) | Brightness and shutdown control input | DC voltage (50–500mV) sets 10–100% LED current; PWM signal enables 1–100% dimming; <28mV disables output. |
| BIAS (2) | Internal switch base current control | Short to GND for max 2A switch current; resistor to GND scales base drive and limits peak LED current. |
| CFB (3) | Loop compensation node | 10nF capacitor to GND stabilizes feedback loop; voltage here integrates IMON–IADJ error current. |
| N/C (4) | No connection | Internally unconnected; must remain floating. |
| ISENSE (5) | Peak switch current sense input | Measures emitter voltage drop across RSENSE; triggers switch turn-off when VISENSE ≥50mV. |
| EMITTER (6,7) | Switch emitter terminals | Both pins connect to top of RSENSE; parallel routing minimizes parasitic inductance in high-di/dt path. |
| COLLECTOR (8,9) | Switch collector terminals | Both pins connect to coil low-side; parallel routing handles up to 2A continuous collector current. |
| M_LOAD (10) | High-side monitor load input | Connects to LED cathode side; senses voltage drop across RM to generate proportional IMON current. |
| M_VIN (11) | High-side monitor supply input | Connects to boost output (LED anode); supplies monitor circuitry and defines IMON reference path. |
| VIN (12) | Main power input | Accepts 1.2–12V; requires local 10µF ceramic decoupling capacitor near pin. |
| TADJ (13) | Thermal compensation input | Voltage divider with NTC thermistor sets foldback onset temperature; 75mV = full current, 50mV = zero current. |
| VREF (14) | Internal 0.5V reference output | Stable 500mV ±20mV source; used to bias ADJ and TADJ networks; drives 100kΩ internal resistor to ADJ. |
| Exposed Pad (15) | Thermal and electrical ground | Must be soldered to large PCB copper pour; provides primary thermal path and reduces EMI coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Bootstrap low-voltage startup | Enables operation from 1.2V input using internal 50kHz oscillator, allowing single-cell battery use without external LDO. |
| Integrated high-side current monitor | Eliminates need for external shunt amplifier; achieves ±3% LED current accuracy with 0.1Ω RM resistor and no calibration. |
| Adjustable soft-start via CFB | 10nF capacitor at CFB controls ramp rate of output current, preventing inrush into capacitive LED loads. |
| Programmable thermal foldback | External NTC/resistor network at TADJ provides linear current reduction from 100% to 0% over user-defined temperature range. |
| Over-temperature shutdown | Internal die sensor disables switch at 150°C junction temperature, protecting device during sustained overload or poor heatsinking. |
Applications
| High-Power LED Flashlights | Emergency Lighting Systems |
|---|---|
Use Scenario: Handheld tactical flashlights powered by two AA/AAA alkaline cells with runtime optimization across battery discharge curve. IC Role / Device Role / Timing Role: Boost controller and current regulator maintaining constant 1A LED output despite VIN dropping from 3.2V to 1.8V. Use Value: Bootstrap mode extends usable battery life by enabling operation down to 1.2V; thermal foldback prevents LED thermal runaway during extended high-output use. | Use Scenario: Self-contained exit sign or corridor light with battery backup, requiring fail-safe dimming and thermal derating. IC Role / Device Role / Timing Role: Primary LED driver during AC failure; monitors LED temperature via NTC and reduces current before junction exceeds safe limit. Use Value: Integrated thermal compensation eliminates need for separate microcontroller-based monitoring; 12µA standby current maximizes battery hold time. |
| LED Back-Up Lighting | General LED Lighting Modules |
Use Scenario: Automotive interior map lights or cargo area illumination with wide input range (9–16V) and vibration resilience. IC Role / Device Role / Timing Role: Constant-current boost driver compensating for alternator ripple and cold-cranking dips below 9V. Use Value: 1.2V start-up capability ensures operation during cranking events; high-side current monitor rejects ground noise common in vehicle chassis returns. | Use Scenario: Commercial signage or architectural accent lighting using 3–5 white LEDs in series driven from 5V USB or 12V wall adapter. IC Role / Device Role / Timing Role: Efficient, compact LED current source with analog/PWM dimming support and minimal BOM count. Use Value: DFN14 package enables <100mm² total solution size; integrated switch and monitor reduce component count by ≥4 vs discrete alternatives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AL8862SP-13 | Fixed-frequency buck-boost controller; external MOSFET; no integrated current monitor or thermal foldback. | Requires external shunt, op-amp, and NTC interface circuitry; higher BOM cost and board area. | Choose for designs needing >1.5A output or programmable switching frequency; not drop-in for ZXLD1321 footprint. |
| LM3407MMX/NOPB | Constant-current buck LED driver; 1.25V reference; no boost capability or thermal foldback. | Limited to VIN > VLED + 0.5V; cannot drive LEDs from sub-2V sources or in boost configuration. | Choose only if input always exceeds LED string voltage; unsuitable for single-cell or emergency backup use cases. |
Compared with AL8862SP-13 and LM3407MMX/NOPB, ZXLD1321DCATC uniquely integrates boost conversion, high-side current sensing, and analog thermal foldback in a single DFN package-reducing design complexity for battery-powered LED systems requiring robustness across voltage and temperature extremes.
Availability
ZXLD1321DCATC is available at Aetrix Electronics and suitable for high-power LED flashlights, emergency lighting systems, and automotive back-up lighting requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for ZXLD1321DCATC includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Diodes Incorporated acquired Zetex Semiconductors in 2008 and maintains its portfolio of high-performance analog and power management ICs targeting industrial, automotive, and consumer applications.
The ZXLD1321 belongs to Zetex's LED Driver product line, engineered specifically for cost-sensitive, battery-operated lighting systems demanding high efficiency, thermal resilience, and minimal external components.
FAQ
What is the minimum input voltage required for ZXLD1321DCATC to start switching?
The ZXLD1321DCATC enters low-voltage start-up mode at VIN = 1.2V, using an internal 50kHz oscillator to initiate boost operation. Normal PFM control resumes once VIN rises above 2.2V, either from battery recovery or bootstrap action. This allows reliable ignition from fully discharged NiMH or alkaline cells without external assist circuitry.
How is LED current accuracy affected by external resistor tolerance?
LED current accuracy depends on RM (M_VIN–M_LOAD resistor) and RSENSE tolerances. With ±1% RM and ±5% RSENSE, total system accuracy remains within ±5% over temperature due to internal 50mV VSENSE matching and 0.5V VREF stability (±20mV). The datasheet specifies ±5% IOUT accuracy under these conditions, excluding external component drift.
Can the ZXLD1321DCATC drive more than 5 white LEDs in series?
No-maximum output voltage is limited by internal switch VCEO (18V) and practical efficiency constraints. At 1A output, five 3.2V white LEDs consume 16V, leaving only 2V headroom for Schottky drop and PCB losses. Driving six LEDs (19.2V) exceeds safe operating area and risks switch breakdown or thermal shutdown under load.
What happens if the TADJ pin is left unconnected?
An unconnected TADJ pin defaults to ~0V due to internal leakage, triggering full thermal foldback and reducing LED current to zero. To disable thermal compensation, TADJ must be actively tied to VREF (0.5V) via a 10kΩ resistor-not left floating. This ensures VTADJ > 75mV and disables the thermal current sink.
ZXLD1321DCATC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- 14-UFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 2V
- Voltage - Supply (Max):
- 12V
- Voltage - Output:
- 18V
- Current - Output / Channel:
- 1A (Switch)
- Frequency:
- 600kHz
- Dimming:
- PWM
- Applications:
- Backlight, Lighting
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DFN4030-14
ZXLD1321DCATC FAQ
1.How can I place an order for ZXLD1321DCATC through Aetrix?
Please submit a Request for Quotation (RFQ) for ZXLD1321DCATC on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ZXLD1321DCATC reliable?
The price and inventory of ZXLD1321DCATC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZXLD1321DCATC is usually 5 days.
3.What payment methods are accepted for ZXLD1321DCATC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZXLD1321DCATC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZXLD1321DCATC?
ZXLD1321DCATC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZXLD1321DCATC order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ZXLD1321DCATC?
For technical support, including ZXLD1321DCATC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZXLD1321DCATC requirements.
6.How does Aetrix verify that ZXLD1321DCATC is sourced from the original manufacturer or authorized distributors?
All ZXLD1321DCATC products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ZXLD1321DCATC meets industry standards.
7.What is the process for return or replacement of ZXLD1321DCATC?
All ZXLD1321DCATC units undergo pre-shipment inspection (PSI). If there is an issue with ZXLD1321DCATC, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ZXLD1321DCATC part is unused and in its original packaging.
Return procedure for ZXLD1321DCATC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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