TMD4903 Datasheet, PDF (70/86 Pages) ams AG – Color and Proximity Sensor Module with mobeam

Figure 81:
External IR LED Using the LDR Pin
TMD4903 − ApplicationInformation
Electrical and Optical Output
The electrical or optical output of the remote control engine
can be realized in three ways: use of the integrated top-facing
LED, use of the LDR pin to directly drive an external LED, or use
of the GPIO pin to drive an external FET and IR LED.
The LDR pin has a regulated current sink with selectable drive
value. This is an attractive way to use an external LED without
having an additional LED drive FET. If this method is to be used,
then LEDA must be disconnected from the circuit. Since the
cathode of the integrated LED is connected to the LDR pin
internal to the module any current that is sourced through LEDA
will reduce the current available on the external remote control
LED. When the remote control functionality is not used the
external LED must be electrically disconnected from the LDR
pin to prevent it from illuminating.
V_BUS
V_LED
V_LED
V_DD
22Ω
VDD
1
1µF
GND ₃
SCL ₂
SDA ₈
TMD4903
µP
4 ^LEDA
6 ^GPIO
V_{DD µP}
1µF >4.7µF
INT
7
LDR
5
Remote Control Circuit Option #1
Recommended Connection: Option number one.
If the LDR pin is not used as the pattern output, the GPIO pin
can be used. With this method both the LEDA and external
remote control IR LED may remain connected to the LED power
supply, but an additional FET is needed to drive the remote
control LED.
Page 70
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ams Datasheet
[v1-12] 2015-May-14