SSL3250A_5

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 05 — 16 December 2009

6 of 26

NXP Semiconductors

SSL3250A

Photo flash dual LED driver

8.2.1 Using the direct enable control

When the Direct enable mode is used, the device can be switched to the various

operational modes using the ACT, EN1 and EN2 control signals. The definition of these

control signals is given in Table 5. The current in the main LED, in Torch mode and Flash

mode and the LED current in the indicator LED can be independently controlled by the

external current setting resistors R_IND, R_TR and R_FL. When no external current

setting resistors are used, the pins should preferably be connected to VIN and the default

current levels for each LED.

The relation between the ACT and EN1, EN2 signals is given in Figure 4. All modes can

be entered from the Standby mode. Entering Torch mode or Indicator mode before

entering Flash mode is not required.

Section 8.2.1, Figure 4. The Flash mode is entered in two steps:

1. Set the correct current and timing values in the current control and timing registers.

This arms the device for the required flash operation.

Table 5.

Enable definition

ACT

EN2

EN1

Operational mode

LED active

0

X

X

Shut-down mode

-

1

0

0

Standby mode

-

1

0

1

Indicator mode

indicator LED

1

1

0

Torch mode

main LED

1

1

1

Flash mode

main LED

Fig 4.

Functional description of the SSL3250A

Standby

Indicator

Flash

Torch

Indicator

EN2

EN1

Shut-down

ACT

Torch

014aaa294

Main LED

current

Indicator

LED current