TFDS4400-TR3 Vishay, TFDS4400-TR3 Datasheet - Page 7

• Manufacturer Part Number: TFDS4400-TR3
• Manufacturer: Vishay
• Type: TX/RXr

Specifications of TFDS4400-TR3

• Data Rate: 115.2Kbps
• Peak Wavelength: 900nm
• Angle Of Half Sensitivity: 48°
• Pulse Width: 8us
• Fall Time: 600/200ns
• Rise Time: 600/1400ns
• Operating Supply Voltage (typ): 2.5/3.3/5V
• Operating Supply Voltage (min): 2/2.7V
• Operating Supply Voltage (max): 5.5V
• Mounting: Surface Mount
• Pin Count: 8
• Operating Temp Range: -25C to 85C
• Operating Temperature Classification: Commercial
• Lead Free Status / Rohs Status: Compliant

The sensitivity control (SC) pin allows the minimum
detection irradiance threshold of the transceiver to be
lowered when set to a logic HIGH. Lowering the
irradiance threshold increases the sensitivity to
infrared signals and increases transmission range up
to 3 meters. However, setting the Pin SC to logic HIGH
also makes the transceiver more susceptable to
transmission errors due to an increased sensitivity to
fluorescent light disturbances. It is recommended to
set the Pin SC to logic LOW or left open if the increased
range is not required or if the system will be operating
in bright ambient light.
The guide pins on the side-view and top-view pack-
ages are internally connected to ground but should not
be connected to the system ground to avoid ground
loops. They should be used for mechanical purposes
only and should be left floating.
Shutdown
The internal switch for the IRED in Vishay SIR
transceivers is designed to be operated like an open
collector driver. Thus, the V
unregulated power supply while only a well regulated
power source with a supply current of 1.3 mA
connected to V
the remainder of the transceiver circuitry in receive
mode. In transmit mode, this current is slightly higher
(approximately 4 mA average at 3 V supply current)
and the voltage is not required to be kept as stable as
in receive mode. A voltage drop of V
down to about 2.0 V when buffering the voltage directly
from the Pin V
This configuration minimizes the influence of high
current surges from the IRED on the internal analog
control circuitry of the transceiver and the application
circuit. Also board space and cost savings can be
achieved by eliminating the additional linear regulator
normally needed for the IRED’s high current
requirements.
The transceiver can be very efficiently shutdown by
keeping the IRED connected to the power supply V
but switching off V
V
microcontroller (see figure 6). In shutdown, current
loss is realized only as leakage current through the
current limiting resistor to the IRED (typically 5 nA).
The settling time after switching V
approximately 50
Document Number 82524
Rev. A1.5, 31-May-00
CC1
/SD
can
CC1
CC1
be
/SD is needed to provide power to
to GND see figure 3.
CC1
s.
provided
/SD. The power source to
Vishay
cc2
source can be an
CC1
directly
TOIM3232
CC1
/SD on again is
is acceptable
from
CC2
a
interface circuit is designed for this shutdown feature.
The V
be used to power the transceiver with the necessary
supply current.
If the microcontroller or the microprocessor is unable
to drive the supply current required by the transceiver,
a low–cost SOT23 pnp transistor can be used to switch
voltage on and off from the regulated power supply
(see figure 7). The additional component cost is
minimal and saves the system designer additional
power supply costs.
As external filter, only a capacitor is recommended.
Supply
Power
Supply
Power
Microcontroller or
Microprocessor
CC_SD
20 mA
+
–
TFDU4100 (Note: Typical Values Listed)
Receive Mode
@ 5 V: I
@ 2.7 V: I
Transmit Mode
@ 5 V: I
@ 2.7 V: I
+
–
TFDU4100 (Note: Typical Values Listed)
Receive Mode
@ 5 V: I
@ 2.7 V: I
Transmit Mode
@ 5 V: I
@ 2.7 V: I
Regulated Power Supply
, S0 or S1 outputs on the TOIM3232 can
Regulated Power Supply
Microcontroller or
Microprocessor
IRED
IRED
IRED
IRED
IRED
IRED
20 mA
IRED
IRED
50 mA
= 210 mA, I
= 210 mA, I
50 mA
= 210 mA, I
= 210 mA, I
= 210 mA, I
= 210 mA, I
Figure 6.
Figure 7.
= 210 mA, I
= 210 mA, I
Vishay Semiconductors
S
S
S
S
= 1.3 mA
S
= 5 mA (Avg.)
S
= 1.3 mA
S
= 5 mA (Avg.)
S
= 1.0 mA
= 3.5 mA (Avg.)
TFDS4400
I
S
= 1.0 mA
= 3.5 mA (Avg.)
I
S
I
IRED
V
R1
Anode
IRED
CC1
I
IRED
V
R1
Anode
CC1
IRED
/SD
www.vishay.com
/SD
14878
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