Overview
The CAT4004AHU2-GT3 is a constant current LED driver produced by onsemi. This device is part of the CAT400XA series, which includes the CAT4002A and CAT4004A models. The CAT4004AHU2-GT3 specifically provides four matched low dropout current sources to drive LEDs. It is designed to handle a wide range of LED forward voltages while maintaining tight current matching across all channels.
The device features a low dropout voltage of 50 mV at 20 mA, making it suitable for powering LEDs directly from a Lithium-ion battery. It also includes a digital dimming interface with 32 linear dimming levels, controlled through the EN/DIM logic input.
The CAT4004AHU2-GT3 is available in a compact 8-pad UDFN package with dimensions of 2 mm x 2 mm and a maximum height of 0.55 mm, making it ideal for space-constrained applications.
Key Specifications
| Parameter | Rating/Value | Unit |
|---|---|---|
| VIN, LEDx, RSET | 6 | V |
| EN/DIM Voltage | 6 | V |
| Storage Temperature Range | −65 to +160 | °C |
| Junction Temperature Range | −40 to +125 | °C |
| Lead Temperature | 300 | °C |
| Quiescent Current (No load, RSET = Float) | 0.2 - 0.5 | mA |
| Shutdown Current | <1 | μA |
| LED Current Setting (RSET = 3.0 kΩ) | 25 | mA |
| LED Current Accuracy | ±1% | |
| LED Channel Matching | ±5% | |
| RSET Pin Regulated Voltage | 0.57 - 0.63 | V |
| Dropout Voltage (90% of nominal LED current) | 50 mV (at 20 mA), 25 mV (at 1 mA) | mV |
| Thermal Shutdown | 150 | °C |
| Thermal Hysteresis | 20 | °C |
| Undervoltage Lockout (UVLO) Threshold | 2.0 | V |
Key Features
- 4 matched low dropout current sources to drive LEDs
- 32 linear dimming levels via 1-wire EZDim interface
- Low dropout voltage of 50 mV at 20 mA
- No switching noise
- Shutdown current less than 1 μA
- LED current set by external resistor (RSET)
- Thermal shutdown protection
- Available in 8-pad UDFN 2 mm x 2 mm and 6-lead SC-70 packages
- Pb-free, Halogen-free/BFR-free, and RoHS compliant
Applications
- LCD display backlight
- Digital still cameras
- Cellular phones
- Handheld devices
Q & A
- What is the primary function of the EN/DIM pin in the CAT4004AHU2-GT3?
The EN/DIM pin serves two primary functions: it enables and disables the device, and it controls the LED current dimming with 32 different levels through a digital interface.
- How is the LED current set in the CAT4004AHU2-GT3?
The LED current is set by an external resistor (RSET) connected between the RSET pin and ground. The formula for calculating the LED current is: LED current ≈ 125 x VRSET / RSET.
- What is the range of input voltage for the CAT4004AHU2-GT3?
The operating input voltage range is from 2.4 V to 5.5 V.
- What happens when the input supply falls below the under-voltage threshold?
If the input supply falls below the under-voltage threshold (2.0 V), all the LED channels are disabled, and the device enters shutdown mode.
- How many dimming levels does the CAT4004AHU2-GT3 support?
The device supports 32 linear dimming levels controlled through the EN/DIM pin.
- What is the thermal shutdown temperature for the CAT4004AHU2-GT3?
The thermal shutdown temperature is 150°C.
- What are the package options for the CAT4004AHU2-GT3?
The device is available in an 8-pad UDFN 2 mm x 2 mm package and a 6-lead SC-70 package.
- Is the CAT4004AHU2-GT3 RoHS compliant?
Yes, the device is Pb-free, Halogen-free/BFR-free, and RoHS compliant.
- What is the dropout voltage at 20 mA for the CAT4004AHU2-GT3?
The dropout voltage at 20 mA is 50 mV.
- How is the LED current adjusted using the EN/DIM pin?
The LED current is adjusted by pulsing the EN/DIM signal. Each consecutive pulse reduces the LED current by about 3.2% of the full scale value until it reaches zero after 31 pulses, then returns to full scale on the next pulse.
