Overview
The CAT4139TD-GT3, produced by onsemi, is a DC/DC step-up converter designed to deliver an accurate constant current, making it ideal for driving LEDs. This device operates at a fixed switching frequency of 1 MHz, allowing the use of small external ceramic capacitors and inductors. It is particularly suited for driving parallel strings of up to five white LEDs in series or up to 22 V. The CAT4139TD-GT3 features a low profile TSOT-23 package, making it suitable for space-critical applications.
Key Specifications
| Parameter | Min | Typ | Max | Units |
|---|---|---|---|---|
| VIN, FB Voltage | -0.3 | 7 | V | |
| SW Voltage | -0.3 | 40 | V | |
| Storage Temperature Range | -65 | 160 | °C | |
| Junction Temperature Range | -40 | 150 | °C | |
| Lead Temperature | 300 | °C | ||
| VIN (Recommended Operating Conditions) | up to 5.5 | V | ||
| Ambient Temperature Range | -40 | 85 | °C | |
| Operating Current (IQ) | 0.6 | 0.1 | 1.5 | mA |
| Shutdown Current (ISD) | 0.1 | 1 | µA | |
| FB Pin Voltage (VFB) | 285 | 300 | 315 | mV |
| Switch Current Limit (ILIM) | 600 | 750 | mA | |
| Switching Frequency (FSW) | 0.8 | 1.0 | 1.3 | MHz |
| Thermal Shutdown (TSD) | 150 | °C | ||
| Under-voltage Lockout (UVLO) Threshold | 1.9 | V |
Key Features
- Fixed 1 MHz switching frequency for low noise operation and compatibility with small external components.
- Drives LED strings up to 22 V and supports up to five white LEDs in series.
- High efficiency of up to 87%.
- Low quiescent ground current of 0.6 mA.
- Soft-start feature to limit in-rush currents.
- Shutdown current less than 1 µA.
- Open LED overvoltage protection and automatic shutdown at 1.9 V (UVLO).
- Thermal overload protection.
- Pb-free, halogen-free/BFR-free, and RoHS compliant.
- Compact TSOT-23 5-lead package with a maximum height of 1 mm.
Applications
- GPS navigation systems.
- Portable media players.
- Handheld devices.
Q & A
- What is the primary function of the CAT4139TD-GT3?
The CAT4139TD-GT3 is a DC/DC step-up converter designed to deliver an accurate constant current for driving LEDs.
- What is the switching frequency of the CAT4139TD-GT3?
The device operates at a fixed switching frequency of 1 MHz.
- How many LEDs can the CAT4139TD-GT3 drive in series?
The device can drive up to five white LEDs in series or up to 22 V.
- What is the efficiency of the CAT4139TD-GT3?
The device has an efficiency of up to 87%.
- What is the quiescent ground current of the CAT4139TD-GT3?
The quiescent ground current is 0.6 mA.
- How does the CAT4139TD-GT3 handle open LED fault conditions?
In the event of an open LED fault, the device enters a very low power mode to prevent overvoltage damage.
- What thermal protection does the CAT4139TD-GT3 have?
The device includes thermal overload protection that shuts down the device if the junction temperature exceeds 150°C.
- What is the package type and dimensions of the CAT4139TD-GT3?
The device is housed in a TSOT-23 5-lead package with a maximum height of 1 mm.
- Is the CAT4139TD-GT3 RoHS compliant?
Yes, the device is Pb-free, halogen-free/BFR-free, and RoHS compliant.
- How is the LED current set in the CAT4139TD-GT3?
The LED current is set by an external resistor (R1) connected between the feedback pin (FB) and ground, using the formula: ILED = 0.3 V / R1.
