Rainbow Electronics ATA6839 - Manual (Page 5)

5
4955C–AUTO–09/07
ATA6839 [Preliminary]
3. Functional Description
3.1 Serial Interface
Data transfer starts with the falling edge of the CS signal. Data must appear at DI synchronized
to CLK and is accepted on the falling edge of the CLK signal. LSB (bit 0, SRR) has to be trans-
ferred first. Execution of new input data is enabled on the rising edge of the CS signal. When CS
is high, pin DO is in a tri-state condition. This output is enabled on the falling edge of CS. Output
data will change their state with the rising edge of CLK and stay stable until the next rising edge
of CLK appears. LSB (bit 0, TP) is transferred first.
Figure 3-1. Data Transfer Input Data Protocol
SRR LS1 HS1 LS2 HS2 LS3 HS3 LS4 HS4 LS5 HS5 LS6 HS6 OLD SCT SI
CS
DI
CLK
DO TP SLS1 SHS1 SLS2 SHS2 SLS3 SHS3 SLS4 SHS4 SLS5 SHS5 SLS6 SHS6 SCD INH PSF
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Table 3-1. Input Data Protocol
Bit Input Register Function
0 SRR
Status register reset (high = reset; the bits PSF, SCD and
overtemperature shutdown in the output data register are set to low)
1 LS1 Controls output LS1 (high = switch output LS1 on)
2 HS1 Controls output HS1 (high = switch output HS1 on)
3 LS2 See LS1
4 HS2 See HS1
5 LS3 See LS1
6 HS3 See HS1
7 LS4 See LS1
8 HS4 See HS1
9 LS5 See LS1
10 HS5 See HS1
11 LS6 See LS1
12 HS6 See HS1
13 OLD Open load detection (low = on)
14 SCT
Programmable time delay for short circuit
(shutdown delay high/low = 12 ms/1.5 ms)
15 SI
Software inhibit; low = standby, high = normal operation
(data transfer is not affected by standby function because the digital
part is still powered)