CN5728

CN5728 is a current modulation circuit operating from 2.85V to 6V, capable of delivering a constant output current up to 1.5A, suitable for driving various types of LEDs including white LEDs. The LED pin current of the CN5728 is set by an external resistor, with a current range of 30mA to 1.5A. An integrated power transistor significantly reduces the external component count. The chip also integrates a status register and oscillator circuit; working in conjunction with the push-button input pin and timing capacitor pin, the CN5728 can cycle the LED sequentially through three or four of the following states: high brightness, low brightness, strobe, and off — making it ideal for flashlight applications. Additional features include chip temperature modulation and a chip enable input. The CN5728 is available in a thermally enhanced 8-pin SOP8 package. The CN5728 is an IC capable of providing current modulation up to 1.5A for high-brightness LEDs. It also integrates an oscillator circuit and status register; working in conjunction with the push-button input pin and timing capacitor pin, the CN5728 can cycle the LED sequentially through three or four of the following states: high brightness, low brightness, strobe, and off. In the low brightness state, the LED current is 36.5% of the LED current in the high brightness state. The CN5728 also features a temperature modulation function. When the junction temperature of the CN5728 reaches 135°C due to excessive ambient temperature, poor heat dissipation, or a short circuit from the LED pin to ground, the internal power management unit automatically reduces the output current at the LED pin to prevent further temperature rise. This feature allows users to maximize the power handling capability of the chip without concern about overheating that could damage the chip or external components.

Applications

• Flashlights
• High-brightness LED drivers
• LED headlamps
• Emergency lights and lighting fixtures

Key features

• Operating voltage range: 2.85V to 6V
• Operating modes: Four-state cycle (high brightness, low brightness, strobe, off); three-state cycle (high brightness, low brightness, off); three-state cycle (high brightness, strobe, off)
• Integrated power transistor
• Low dropout: 0.4V@1.5A
• LED pin output current up to 1.5A
• Output current accuracy: ±5%
• Thermal modulation function
• Operating temperature range: -40°C to 85°C
• Enhanced thermal dissipation SOP8 package (8-pin)
• Lead-free, RoHS compliant, halogen-free