Figure 11. Direct Control Mode, time diagram

6.3

Synchronous Control Mode (SCM)

When SYNC and LOAD inputs are independently driven, the device can operate in synchronous control mode

(SCM). The SCM is used to reduce the jittering of the outputs and to drive all outputs of different devices at the

same time. In SCM the LOAD signal is forced low to update the input buffer while the SYNC signal is high. The

LOAD signal is raised and the SYNC one is forced low for at least tSYNC(SCM). During this period, the internal

refresh is disabled and any pending transmission between the low voltage and the isolated side is completed.

When the SYNC signal is raised the channel output configuration is changed according to the one stored in the

input. If the tSYNC(SCM) limit is met, the maximum jitter of the channel outputs is tjitter(SCM). If more devices share

the same SYNC signal, all device outputs change simultaneously with a maximum jitter related to maximum delay

and maximum jitter for single device.

Table 16. Interface signal operation in synchronous mode

LOAD

SYNC

OUT_EN

Device behavior

Don't care Don't care

Low(1)

The outputs are disabled (turned off)

High

High

High

The outputs are left unchanged

Low

High

High

The input buffer is enabled, the outputs are left unchanged

High

Low

High

The internal refresh signal is disabled, the transmission buffer is updated and the outputs

are left unchanged

Low

Low

High

Should be avoided (DCM operation only)

1. The outputs are turned off on OUT_EN falling edge and they are kept disabled as long as it is low

Figure 12. Synchronous Control Mode, IC configuration

ISO808, ISO808-1

Synchronous Control Mode (SCM)

DS14169 - Rev 1

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