PWBS331 DC transmission data bus chip achieves the function of delivery both of the UART data and DC power on only two wires. Ideal solution for long distance RS485 communication with DC transmission ability , adapts tree network RS485, star network RS485 well. 3000m long distance reliable work.

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DC TRANSMISSION DATA BUS PWBS331 DATASHEET
KEY FEATURES
Delivery both of the DC power and data
on only two wires. No need isolated
design. Excellent anti‐interference ability.
Can work close to AC power lines
Allows to 500 slave nodes on the BUS
(compatible to RS485 with one RS485
chip)
Achieves to 3000m in ideal environment
Non‐polarity. Easy to use in engineering
field.
Supports to any network: Tree, star, BUS
No type limit on BUS wires
Supports 17 to 48V on the BUS
Transparent UART interface, compatible
to RS485 interface directly
Self adaption to 9600bps and 2400bps in
half‐duplex
Low cost solution with simple circuit
Free design in isolation or non‐isolation.
Guarantee the best EMC performance
because of the high power BUS lines.
APPLICATION
Automation control
Instrument and sensors
DESCRIPTION
PWBS331 is the slave node's chip which works
with the host PWBS751 to communicate and
get DC power from the DC transmission BUS.
PWBS331 simplifies the traditional separated
solution of DC power and communication
data lines by the way of transmitting signal
with full amplitude DC voltage pulse wave and
receiving signal with current. That guarantees
the highest reliable communication result in
industry.
PWBS331 adapts to any type of the wires, and
can work in any topology network with no
polarity limit. That simplifies the engineering
connection of BUS lines.
PWBS331 works with host module PWBS751
to delivery both of the power and signal data.
ORDER PACKAGE INFORMATION
1 TUBE 100 pieces
1 ROLL 3000 pieces

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ABSOLUTE MAXIMUM RATINGS(1)
Table1.
PARAMETER RANGE
Vcc to Ground (GNG) ‐0.3V~6.0V
TX, RX, PI, PO ‐0.3V~Vcc+0.3V
Storage temperature ‐65 to +150℃
Operating temperature ‐40℃ to +85℃
Soldering temperature (10s) 220℃
ESD (HBM) 4KV
ESD (CDM) 2KV
ESD (MM) 400V
(1) Stresses beyond those listed under
"Absolute Maximum Ratings" may cause
permanent damage to the device. Working on
the absolute maximum rating in long time will
cause unstable performance
PIN NAME
Fig.1
ESD warning
ESD (Electrostatic discharge) protection
notice
Circuit board and the components on the
board may have static with high power.
Discharging may cause damage on the device.
ESD protection is important to ensure the
best performance of the device.
Table2. PIN DESCRIPTION
PIN NUMBER PIN NAME FUNCTION
1 VCC Power supply
2 TX Data transmitter
3 RX Data receiver
4 NC No connection
5 PO Square wave BUS signal output
6 PI Square wave BUS signal input
7 NC No connection
8 GND Ground

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GENERAL ELECTRICAL CHARACTERISTICS
All voltage referenced to GND, unless otherwise noted
Table3.
PARAMETER CONDITIONS MIN TYPE MAX UNIT
DC electrical characteristics
VCC power supply input Test on Vcc 2.7 5.5 V
ICC quiescent current Vcc=3.3V, no data communicate 0.8 mA
Vcc=5V, no data communicate 1.2 mA
UART electrical characteristics
VIL RX low level voltage 2.7<Vcc<5.5V 0.2Vcc V
VIH RX high level voltage 2.7<Vcc<5.5V 0.6Vcc V
VOL TX low level voltage ITX=1.1mA 0.6 V
VOH TX high level voltage ITX=1.1mA Vcc‐0.7 V
UART timer characteristics
TON power on delay
(1)
2 20 mS
Tbit communication time for 1bit 9600bps 100 104 108 uS
2400bps 410 416 428 uS
Td(TX) transmitting delay
(2)
11*Tbit uS
Td(RX) receiving delay
(2)
11*Tbit uS
(1) The delay time from power on to the device working well
(2) The delay time caused by data buffer. No more extra delay time after the device transmitting or
receiving in continues
UART INTERFACE
PWBS331 detects and adapts the data rate of 9600bps or 2400bps automatically. Transmit and
receive 8bits or 9bits automatically. The 9th bit can be used as data, check or address
8bits mode: start + 8bits data + stop
9bits mode: start + 8bits data + 9th data+ stop

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APPLICATION GUIDE
Target power got from transmission BUS
DC output can be got from the DCS terminal
on fig.6. This terminal deliveries rectified DC
power which comes from square wave BUS
and host side. This terminal can also be used
directly as a DC output or use DC/DC (LDO) to
have a target fixed output.
Notice: The target load can’t be connected to
the transmission BUS lines directly. That may
cause a protection action by host side.
Target load
DC transmission BUS provides high power DC
output to slave nodes. Target load can be any
style: resistance, capacitive, inductive load
from motor, electric actuator, electric relay,
high power LED and so on. Fluctuant current
on the load won't influence the
communication ability on the BUS.
Vcc on PWBS331
Vcc on PWBS331 can be large range to adapt
any LDO or DC/DC converter. Vcc also can
share from the power of MCU. It can be got
from rectified BUS or local battery of other
way.
FUSE and protection circuit on slave site
The fuse on fig.6 can be PPTC (Polyer Positive
Temperature Coefficent) or resistance, which
can avoid the circuit short and surging caused
by power on. Fuse can help to make the
damaged slave node break away from BUS
system, and then host side can detect the
fault on slave site. Fuse is not essential.
Pure load in system
If there are pure loads in slave nodes of the
system, fig.5 a simple circuit can be used to
down the total cost.

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Note:
BRIDGE: MB6S or 1N4007 (M7). BRIDGE can't use schottky bridge rectifier in here.
D1: US1M or RS1M. Here must be fast recovery diode
R1, R2: Do not change value on these two parts.
CX1 CX2: EMC capacitor, range from 30pF to 100pF
C1 and the output wave on DCS terminal
C1 is storage energy capacitor to make a stabilizing voltage output. C1 is selected by target
current load. Voltage wave on the DCS terminal has no influence on the communication ability.
The requirement on DCS terminal must be high than 10V. C1 can be electrolytic capacitor and
tantalum capacitor or ceramic capacitor. It is the best to use 470uf or 1000uF
Power level on the transmission BUS lines
There must be at least 12V peak voltage on the BUS line's slave site to ensure PWBS331 working
well. Please provide right DC input to host site to make sure the slave terminal of BUS can be high
than 12V.
APPLICATION CIRCUIT
Isolated design and other power supply source
If slave node needs power from other source such as local AC commercial power, please refer
fig.7 circuit below.
Compare with the isolated RS485 application, below circuit doesn't need isolated DC/DC power
which can down the cost. Power on the op‐coupler side can be got from the DC transmission
BUS.
Battery backup for slave node
If adopts battery backup, please refer fig.8 which means the power source for slave node can be
got from either of the BUS or battery

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PACKAGE INFORMATION
SOIC‐8
Note:
1. Pin1 point may locate in different position, but must be in the shadow part
2. All the unites are millimeter
3. Size C and D do not includes trim and bump. Trim and bump are low than 0.15mm
Suggested pad