AS3645 austriamicrosystems, AS3645 Datasheet - Page 27

• Manufacturer Part Number: AS3645
• Description: 1000/720ma Ultra Small High Efficient Single/dual Led Flash Driver With Safety Features
• Manufacturer: austriamicrosystems

AS3645
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
For a very straightforward control (parallel control) use following circuit (R
AS3645B):
Figure 29. Application Circuit using parallel interface mode
TXMask-ing of battery current - only AS3645B
If the battery has to supply two high current loads at the same time (e.g. the AS3645 flash and a RF-power amplifier) it
is possible, that the total current causes a high voltage drop on the battery and with a low battery resulting in a shut-
down of the complete system. In order to avoid this shutdown, the AS3645 can reduce its current with the signal
‘TXMask’ using the circuit shown in
The TXMask signal is connected to e.g. the (RF-) power amplifier enable pin (active high if the PA is enabled). This
reduces the flash current if the power amplifier is enabled and avoids the unexpected shutdown of the system.
Note: The voltage on I2C/EN in shutdown of the AS3645 should be less than V
External Components
Input Capacitor C
Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. Ceramic
capacitors are required for input decoupling and should be located as close to the device as is practical.
Table 16. Recommended Input Capacitor
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GRM188R60J126
Part Number
neously into I
The internal flash timeout timer (t
function (see
VIN
2
Flash Timeout on page
C mode.
10µF +/-10%
>5µF@1.9V
>4µF@5V
Figure
C
FLASHTIMEOUT
29.
11).
TC Code
X5R
Revision 1.6
) to limit the total flash duration, is not affected by the TXMask
30m Ω
ESR
Voltage
Rated
6V3
ISET
AS3645
or R
TXMASK
TXMASK
0603
Size
(0.5V) to avoid switching erro-
can only be used for
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Manufacturer
Murata
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