Datasheet

DATA IN
Start
DATA OUT ACK
RFA A1 A0 D4 D3 D2 D1 D0DA7
0
DA6
1
DA5
0
DA4
0
DA3
1
DA2
1
DA1
1
DA0
0
Device Address DATABYTE
EOS Start EOS
Start
DA7
0
t
Start
Mode,Static
HighorLow
Mode,Static
HighorLow
DATA IN
t
Start
T
EOS
T
EOS
DA0
0
RFA
0
D0
1
AddressByte DATA Byte
TPS62420, TPS62421
SLVS676C –JUNE 2006–REVISED JUNE 2010 www.ti.com
MODE Selection
Because of the MODE/DATA pin is used for two functions, interface and a MODE selection, the device needs to
determine when it has to decode the bit stream or to change the operation mode.
The device enters forced PWM mode operation immediately whenever the MODE/DATA pin turns to high level.
The device stays also in forced PWM mode during the whole time of a protocol reception.
With a falling edge on the MODE/DATA pin the device starts bit decoding. If the MODE/DATA pin stays low for at
least t
timeout
, the device get’s an internal timeout and Power Save Mode operation is enabled.
A protocol which is sent within this time will be ignored, because the falling edge for the Mode change will be first
interpreted as start of the first bit. In this case it is recommended to send first the protocol and change at the end
of the protocol to Power Save Mode.
Figure 28. Easy Scale Protocol Overview
Table 3. Easy Scale Bit Description
BYTE BIT NAME TRANSMISSION DESCRIPTION
NUMBER DIRECTION
Device 7 DA7 IN 0 MSB device address
Address
6 DA6 IN 1
Byte
5 DA5 IN 0
4 DA4 IN 0
4Ehex 3 DA3 IN 1
2 DA2 IN 1
1 DA1 IN 1
0 DA0 IN 0 LSB device address
Databyte 7(MSB) RFA IN Request For Acknowledge, if high, Acknowledge condition will applied by the device
6 A1 Address Bit 1
5 A0 Address Bit 0
4 D4 Data Bit 4
3 D3 Data Bit 3
2 D2 Data Bit 2
1 D1 Data Bit 1
0(LSB) D0 Data Bit 0
ACK OUT Acknowledge condition active 0, this condition will only be applied in case RFA bit is
set. Open drain output, Line needs to be pulled high by the host with a pullup
resistor.
This feature can only be used if the master has an open drain output stage. In case
of a push pull output stage Acknowledge condition may not be requested!
Figure 29. Easy Scale Protocol Without Acknowledge
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