I/O Pins Configuration Table
Pin
1
2
3
Symbol
LED A
LED C
TXD
Description
LED Anode
LED Cathode
Transmit Data
I/O Type
Input
Output
Input,
Active High
Output,
Active Low
Function
This pin can be connected directly to V
CC
(i.e., without series resistor)
at less than 3 V. Please refer to Table 1 for V
CC
versus Series Resistor, R1.
Leave this pin unconnected.
This pin is used to transmit serial data when SD/Mode pin is low. If this
pin is held high longer than ~100
µs,
the LED would be turned off when
used in conjunction with the SD/Mode pin. TXD is low at initialization.
This pin is capable of driving a standard CMOS or TTL load. No external
pull-up or pull-down resistor is required. It is in tri-state mode when the
transceiver is in shutdown mode and during digital serial programming
operations. RXD is high at initialization.
The transceiver is in shutdown mode if this pin is high for more than
400
µs.
On the falling edge of this signal, the state of the TXD pin sampled
and used to set receiver low bandwidth (TXD=low) or high bandwidth
(TXD=high) mode. See Figure 2 for bandwidth selection timings. SD is low
at initialization.
Regulated, 2.7 to 5.25 Volts.
4
RXD
Receive Data
5
SD/Mode Shutdown/
Mode Select
Input,
Active High
6
7
8
–
V
CC
NC
GND
Shield
Supply
Voltage
No Connect
Ground
EMI Shield
Supply
Voltage
No Connect
Ground
EMI Shield
Connect to system ground.
Connect to system ground via a low inductance trace. For best
performance, do not connect directly to the transceiver pin GND.
Recommended Application Circuit Components
Component
Recommended Value
R1
0
Ω ±
5%, 0.5 Watt, for 2.7 V
1.8
Ω ±
5%, 0.5 Watt, for 3.0 V
4.7
Ω ±
5%, 0.5 Watt, for 3.3 V
6.8
Ω ±
5%, 0.5 Watt, for 3.5 V
CX1
0.47
µF ±
20%, X7R Ceramic
CX2
6.8
µF ±
20%, Tantalum
Notes
1
2
Notes:
1. CX1 must be placed within 0.7 cm of the HSDL-3603 to obtain optimum noise immunity.
2. In environments with noisy power supplies, supply rejection performance can be enhanced
by including CX2, as shown in Figure 1: ”HSDL-3603 Functional Block Diagram“ on Page 2.
3
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