Datasheet

15 SERDESUB-21USB User’s Guide SNLU101 – April 2012
JP4,VR1: Address Decoder
Reference Description Setting Connector
JP4
DS90UB904Q
I
2
C Device ID Address
Selection
Default address: 0xC0’h
Enabled –
With jumper
VSS –
Default address
(Default)
JP4 &
VR1
RID value adjustment
(via screw)
JP4 MUST
have a jumper to
use VR1 potentiometer.
VR1 = 0Ω to 100KΩ
Clockwise
Decreases
RID value
Counter-
Clockwise
Increases
R
ID value
The ID[x] (CAD) pin is used to set the slave address of the DS90UB904Q (I
2
C only) to
allow up to six devices on the bus using only a single pin. The Address Decoder employs a
10 k pull up resistor to VDD 1.8V and a variable potentiometer (VR1) pull down resistor
R
ID
to generate six unique values based on the table below. Once the address bits are
latched on power up, the device will keep the slave address until a power down or reset
condition occurs.
Table 2. ID[x] Resistor Value – DS90UB904Q Slave Address
Rid Resistor Ω Address 7'b
Address 8'b
0 appended (WRITE)
0
7b' 110 0000 (h'60) 8b' 1100 0000 (h'C0)
2.0K
7b' 110 0001 (h'61) 8b' 1100 0010 (h'C2)
4.7K
7b' 110 0010 (h'62) 8b' 1100 0100 (h'C4)
8.2K
7b' 110 0011 (h'62) 8b' 1101 0110 (h'C6)
12.1K
7b' 110 0100 (h'62) 8b' 1101 1000 (h'C8)
39.0K
7b' 110 0110 (h'66) 8b' 1100 1100 (h'CC)