ssl3250a NXP Semiconductors, ssl3250a Datasheet - Page 11

• Manufacturer Part Number: ssl3250a
• Description: Photo ?ash Dual Led Driver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SSL3250A_2
Product data sheet
8.3.7 Indicator LED
The indicator LED is connected between the V
input pin. Internally a linear current sink controls the indicator LED current to reach the
required current level.
In I
internal 3-bit register sets the actual indicator LED according to the formula in
The external resistor R_IND is ignored.
When using the Direct enable mode, the indicator current can be determined by an
external resistor R_IND. The indicator current is defined using
between 2.5 mA and 20 mA. When not using the resistor, the indicator current will be set
to a default level of 10 mA. This current is similar to connecting an external resistor of
50 k . Entering Flash mode in Direct enable mode can be done using the EN1 and EN2
pins. The LED will stay on in Flash mode for as long as the enable pins are set.
If there is no resistor connected to the R_IND pin, it can either be left unconnected or
connected to VIN. Never connect the R_IND pin to GND since it will cause unnecessary
reference currents to flow to GND.
Figure 11
illustrates the Indicator mode current setting equation for the Direct enable mode.
I
I
I _IND
I _IND
Fig 10. The inductor current during TxMask
2
C mode, the indicator LED current can be set between 2.5 mA and 17.5 mA. The
Average
inductor
T Mask
=
=
current
Register
----------------- -
R
50 k
illustrates the Indicator mode current setting equation for I
R_IND
10 mA
2.5 mA
Rev. 02 — 21 April 2009
t < 50 s
BAT
and the dedicated indicator LED current
Flash
Photo flash dual LED driver
Equation
SSL3250A
2
C, while
© NXP B.V. 2009. All rights reserved.
7. It can be set
014aaa296
Equation
Figure 12
11 of 26
(6)
(7)
6.