Charge Pump, 7-Channel Smart LED Driver with I2C Interface
The light intensity thresholds are fully programmable via the I2C® interface. A second phototransistor input, with dedicated comparators, improves the ambient light detection levels for various user operating conditions.
The ADP8860 allows as many as six LEDs to be independently driven up to 30 mA (maximum). A seventh LED can be driven to 60 mA (maximum). All LEDs are programmable for minimum/ maximum current and fade in/out times via the I2C interface. These LEDs can also be combined into groups to reduce the processor instructions during fade in/out. Driving this entire configuration is a two-capacitor charge pump with gains of 1×, 1.5×, and 2×. This setup is capable of driving a maximum IOUT of 240 mA from a supply of 2.5 V to 5.5 V. The device includes a variety of safety features including shortcircuit, overvoltage, and overtemperature protection. These features allow easy implementation of a safe and robust design. Additionally, input inrush currents are limited via an integrated soft start combined with controlled input to output isolation. The ADP8860 is available in two package types, either a compact 2 mm × 2.4 mm × 0.6 mm WLCSP (wafer level chip scale package) or a small LFCSP (lead frame chip scale package).
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
This describes the functionality of the Analog Devices, Inc., ADP8860 and provides software development guidelines. The ADP8860 communicates with an external processor using an I2C interface and an interrupt line (nINT). The processor sends initialization and activation commands to the ADP8860, which acts as a slave device.
The interrupt line, from the ADP8860 to the processor, is used to indicate a failure condition, such as a thermal shutdown or an overvoltage and LED/output short circuit, or to indicate a light level threshold has been crossed. All interrupt sources are maskable. Refer to Figure 1 for a typical application diagram. Figure 2 shows a schematic with keypad light control.
The interrupt line is active low; each interrupt source has an individual masking bit. The processor can reset the ADP8860 anytime by pulling the nRST line low; this operation reinitia-lizes the ADP8860 at the default state and places the device in standby mode.
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