Shutdown

External

Torch

Standby

Output On

Strobe

Flash

I2C Flash

External

Torch

Assist Light

LM3565

SNVS957 – JANUARY 2013

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In assist mode, by setting the PWM bit in the Strobe signaling register (PWM in register 0x06) to a '1', and

toggling the Strobe pin high and low, the diode current will transition between the target assist current and 10

mA. When the Strobe pin is high ('1'), the assist current is equal to the target LED current. When the Strobe pin

is low ('0'), the assist current is equal to 10 mA. The diode current is always ramped up to 90 mA, then reduced

to 60 mA if the assist target current is set to 60 mA. The transition between the full-assist current and the 10 mA

current level is done in one step.

TORCH Pin

The Torch pin of the LM3565, depending on the state and configuration, allows the user to enable Torch/Assist

(ETEN bit in register 0x03) must be set to a '1' to allow an external torch (default value = '1'). The torch mode

current is equal to the Assist mode current level stored in register 0x02 (AS0 bit, default value = '0' or 60 mA). In

shutdown mode, driving the Torch pin high will enable the LM3565 and drive the flash LEDs at 60 mA.

TX-MASK Pin

The TX-Mask pin provides the RF PA a direct method to reduce the flash current by a predetermined value

stored in the TX-Mask register (0x03), to prevent a battery over-current fault. When the TX-Mask pin is set low,

the normal target current is realized. When the TX-Mask pin is set high, the flash current is reduced. The flash

current is not ramped during the transition from full-scale to the reduced level; the flash current is ramped when

transitioning back to the full-scale value from the reduced value. As in the Fflash PWM Mode, the lowest flash

current is set to 60 mA.

Fault Protections

The LM3565 has numerous internal fault protection mechanisms to help prevent damage to the LM3565 as well

as the system in the event of a fault. Most fault conditions will cause the LM3565 to enter Shutdown Mode and

will report a fault to the fault register (0x08) or (0x09). The faults that can be detected are as follows:

•

Over-Voltage Protection (VOUT)

•

Short-Circuit Protection (VOUT and VLED)

•

Over-Temperature Protection

•

Flash Time-Out

•

TX-Mask Event

•

Under-Voltage Lock-Out

•

Input Low Voltage Detect

•

Inductor Current Limit (not reported)

•

Output Capacitor Open Protection

Figure 47. Mode Diagram

16

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