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LM3560

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SNOSB43B – SEPTEMBER 2011 – REVISED AUGUST 2013

Table 2. Privacy Indicate (PWM'd Torch) Possible Current

Settings(1) (continued)

Privacy Current Setting

Privacy Indicate Duty Cycle

ILED1 or ILED2

(Enable Register Bit [2])

Privacy Register Bits[2:0]

(Single LED)

0 = 31.25mA peak

see (Table 5)

1 = 250mA peak

101

18.75 mA

110

21.875 mA

111

25 mA

000

25 mA

001

50 mA

010

75 mA

011

100 mA

100

125 mA

101

150 mA

110

175 mA

111

200 mA

POWER AMPLIFIER SYNCHRONIZATION (TX1)

The TX1/TORCH/GPIO1 pin has a triple function. With Configuration Register 1 Bit [7] = 0 (default)

TX1/TORCH/GPIO1 is a Power Amplifier Synchronization input (TX1 mode). This mode is designed to reduce

the flash LED current when TX1 is driven high (active high polarity) or driven low (active low polarity). When the

LM3560 is engaged in a Flash event and TX1/TORCH is driven high, the active current sources (LED1 and/or

LED2) are forced into Torch mode at the programmed Torch current setting. If TX1 is then pulled low before the

Flash pulse terminates, the LED current will return to the previous Flash current level. At the end of the Flash

timeout, whether the TX1/TORCH pin is high or low, the LED current will turn off.

The polarity of TX1 can be changed from active high to active low by writing a 0 to bit [5] of Configuration

Figure 28 details the functionality of the TX1 Interrupt.

TX1 Shutdown

TX1 also has the capability to force shutdown. Bit [4] of Configuration Register 2 set to a '1', changes TX1 from a

force Torch when active to a force shutdown when active. For example, if TX1/TORCH/GPIO1 is configured for

TX1 mode with active high polarity, and bit[4] of Configuration Register 2 is set to '1' , then when TX1 is driven

high, the active current sources (LED1 and/or LED2) will be forced into shutdown. Once the active current

sources are forced into shutdown by activating TX1, the current sources can only be re-enabled into flash mode

if TX1 is pulled low and the Flags Register is read back. If only the Flags register is read back and TX1 is kept

high the device will be re-enabled into torch mode and not shutdown. This occurs because the TX1 shutdown

feature is an edge-triggered event. With active high polarity the TX1 shutdown requires a rising edge at TX1 in

order to force the current source into shutdown. Once shut down, it takes a read back of the flags Register and

another rising edge at TX1 to force shutdown again. Figure 30 details the different responses of the TX1

shutdown mode.

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