feature

Record and playback blinking patterns Single-wire digital control of LED blink rate and brightness Resistor programmable LED maximum current Thermal Shutdown Protection Undervoltage Lockout Protection 6-Pin 3.0 x 3.0mm MLP Package

application

mobile phone, smart phone pocket pc, bluetooth 8482 ; headset pda, dsc, pmp and mp3 player laptop

illustrate

The FAN5645 is a flexible and compact solution. LED indicator flashes. An internal programmable blinking algorithm eliminates any need for continuous system processor control. This means longer battery life because the system processor isn't waking up from sleep mode just to blink the LEDs. An extremely low voltage drop of 40 mV is allowed without any inductors or switched capacitors. An external resistor sets the LED output current level. LED blinking frequency and intensity determined by a simple one-wire interface. In shutdown mode, the supply current is reduced to 0.3µA (typ). The FAN5645 is available in a 6-pin molded lead-free package (MLP).

Circuit Description Mode of Operation: When powered on, the device is in stop ("sleep") mode until a rising edge of the control signal is detected, and the device enters active mode. Active mode can train, run, run once, or resume after reset, depending on the signal applied to the control. The initialization reference and circuit remain in sleep mode until Vin crosses the UVLO threshold and a rising edge is detected on the ctrl pin. When the IC is in sleep mode, all internal bias circuits are disabled. The registers are all reset to 0 on training power-up. The training modality IC can record up to three distinct high (t) and low (toff) times. These times were recorded during training with six internal 8-bit counters, one for each different time. If the training pulse ON or OFF time exceeds the maximum clock count, the value remains at the maximum value. The training pattern consists of the following sequence: 1. Two control pulses, done within TCMD1. The duration of the high control pulse should be greater than 2 microseconds and less than 55 microseconds and the control pulse should be greater than 2 microseconds. 2.CTRL remains low, at least tftpr(min), but less than tftpr(max), from the control pulse. 3. Between one and three sets of training pulses, one of which defines the on-time of the LEDs when the rest time is up. 4. Three control pulses are completed within tcmd2, indicating the end of training. The high time of the control pulse should be greater than 2 microseconds and less than 55 microseconds. The shorter time between two control pulses is greater than 2 microseconds. 5. The IC enters stop (sleep) mode and is able to receive new commands only after tcmd2 expires. 6. If no control pulse is received after training to maximize the output, the IC enters stop (sleep) mode automatically.

Run Mode When CTRL is raised and held high, and the training registers are not all zeros, the repeated playback of the training sequence begins. The delay between CTRL high and LED on is TDLY1. When ctrl subsequently goes low, the IC turns off the LED and enters stop (sleep) mode. After a tcmd2 time, a new one can be processed.

run once mode when the IC receives four consecutive control pulses in tcmd1, then press ctrl to go high after at min tftpr(min), but less than tftpr(max), ic play back to training mode once, then enter stop (Sleep) mode after the training sequence is complete. This assumes that the training registers are not all zeros.

Reset and Follow Mode Reset mode consists of two control pulses, then ctrl executes much lower than TTIMEOUT. The insurer accepts all training registers to zero and then enters stop (sleep) mode.

A set of control pulses. When the control signal disappears low, the LED current is turned off and the IC enters a stop state (sleep) mode. A tcmd2 wait period, on the trailing edge of the last ctrl input, before new commands can be received and processed. Note that it is possible to enter follow mode after power on because all registers are cleared on power up and moving up, the device appears to be in reset mode.

Over current, over temperature and under voltage faults if the ISET pin is too low to ground or the RSET resistor value. If the result is that the LED current is greater than three times the maximum programmed output current (60mA), the IC turns off its output current and disables the reference voltage developed on the ISET pin. When the IC exceeds 150 °C, this also causes the IC to turn off its output current and disable the reference voltage generated on the ISET pin until the IC cools down to about 20°C. If any fault occurs, the IC turns off the output LED current and disables the generated reference voltage on the ISET pin. In the event of a short circuit or overtemperature playback mode fails, replays when the next playback pulse (ton) occurs. If a short circuit or overtemperature fault mode occurs during follower, the LED goes off, restarts, and then the follower mode attempts to restore the state of the LED current control line based on the current. In the event of an undervoltage fault, the IC will turn off the LEDs and enter sleep mode until the next control pulse comes, at which point the IC attempts to wake up. Application Information Setting the LED current LED forward current is determined by an external resistor, RSET, according to: ILED accuracy is determined by input voltage and ambient temperature range and RSET resistance. For best accuracy, rset should be a precision resistor connected near the IC pins, so the voltage across RSET and between the ISET and GND pins. Setting the LED turn-on time below 20-30 milliseconds appears as a flash, rather than in a timely manner to the observer. This flash of light is determined by the energy delivered at the time of the flash. It is possible to change the brightness frequency above 40Hz by changing the on/off time ratio. Because the time resolution is in 1-millisecond increments, 20 discrete levels of dimming function brightness can be implemented in software. Select external components to add a 0.1µF or higher ceramic capacitor between VIN and ground to lower the power line. The minimum value of VIN (vin) should be at least over vf to ensure that the LED current is at the correct value. Instead, the LEDs should be selected so that VF at the specified current is at least 40 mV lower than the lowest VIN. LED is used as blinking indicator, by FAN5645, can be white or any color. Forward current-voltage characteristics and absolute maximum ratings are provided by manufacturers in their specifications. A typical forward current of 15mA gives 1.9V for red and orange, 2V for yellow, 2.1V for green, 3.3V for bright white, bright non-yellow-green, and most blue types. Only meet the conditions favorable to the maximum current rating of the LED, with little or no heat build-up. Some LED current ratings assume a very favorable environment for testing - eg ambient air temperature does not exceed 25°C and good thermal conduction leads are installed. Operating the LED in the specified location for maximum rated current laboratory conditions will cause the LED to lose half of its light output life expectancy after rating (20000 to 100000 hours), best case.