AS3665 datasheet(11/78 Pages) AMSCO

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AS3665

Datasheet, Confidential - D e taile d D e scri pti on Ti ming Diag r ams

8 Detailed Description

The AS3665 is a fixed frequency charge pump. Its output (VOUT) is connected to nine current sources (LED1..LED9).

A sophisticated command based pattern generator with three sequencers controls the nine PWM generators (12 bit

resolution), which are connected to the current sources.

Commands are downloaded to the AS3665 internal memory space and can be executed autonomously in the three

sequencers. The commands are optimized for lighting applications (e.g. a single command executes logarithmic up

dimming). It supports command flow control (like unconditional and conditional jumps). Variables which are accessible

through the I

2C interface allow control of the program execution by the I2C interface and communication between the

three sequencers.

The three sequencers can be dynamically assigned to any of the nine outputs (under program control).

The AS3665 supports an audio input pin INT/AUDIO_IN which allows the control of patterns depending on an audio

input signal. This audio input can be feed through internal digital filters for better visual appearance.

If the audio feature is not used, the pin INT/AUDIO_IN can be used as interrupt output

1 to send interrupts.

The AS3665 is controlled by an I

2C interface and additional dedicated control lines. An EN input operates as a global

enable/disable pin and with the pin TRIG several AS3665 can be synchronized in a system. A separate CLK32K input

can be used to set an exact clock input frequency (all internal timings can be derived either from CLK32K or an internal

oscillator). The I

2C address is selectable by the pin ADDR - see I2C Address selection on page 40. A GPO pin can be

used for external control or as an additional ADC input.

The AS3665 supports LED testing (verification of the performance of the connected LEDs in an assembled system).

Following blocks are included inside the AS3665:

- Low Noise charge pump operating in 1:1, 1:1.5 and 1:2

- Automatic mode switching of the charge pump (up & down)

- 1MHz oscillator

- Internal LDO for powering the internal circuitry

- Audio processing of an analog input signal

- Overtemperature Protection

- Temperature Measurements of the AS3665

- 10 Bit ADC

- 9x12 bit, 1x8 bit PWM Generators

- 6 accurate current sources connected to VCP

- 3 accurate current source configurable to be connected to VBAT or VCP (to improve efficiency e.g. of red LEDs)

- Internal memory for the program execution

- 3 sequencers (3 parallel processing units)

- a fully programmable multiplexer connecting the three sequencers to the 10 PWM generators

- Automatic shutdown to safe power (if SCL and SDA=0 for 100ms)

1. INT/AUDIO_IN is an open drain output. Several interrupt can be easily combined externally.

AS3665 Datasheet(PDF) 11 Page - ams AG

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