ZM7300G Series Digital Power Manager
Data Sheet
converters and then turn them on, if the Auto Turn-On is enabled in the POL Group configuration
window shown in Figure 10. Otherwise, the user will need to send the turn-on command via the I2C
bus.
When the IBV exceeds the IBH threshold plus the hysteresis, the DPM will pull OK lines low turning off
all POL converters. The POL converters will execute regular turn-off ramping their output voltages
down according to the turn-off delay and falling slew rate settings. In addition, the DPM will save the
contents of the Run Time Counter into the non-volatile memory. If the IBV does not decrease below the
IBH threshold minus the hysteresis within the next 50ms, the DPM will pull low the FE_EN output and
clear all bits in the POL Programming Status registers. The IBV High bit in the IBS Monitoring Window
will change to red. If the IBV still does not change, in 50ms the DPM will pull the CB pin high for 1ms to
trigger an optional crowbar protection.
One second after the IBV decreases below the IBH threshold minus the hysteresis, the DPM will pull the
FE_EN high and program all POL converters. Upon completion of the programming process, the DPM
will turn on the POL converters, if the Auto Turn-On is enabled in the POL Group configuration window
shown in Figure 10.
The propagation delay between the IBV increasing/decreasing above/below corresponding thresholds
and the DPM pulling down OK lines and triggering the turn-off process is approximately 1ms.
10.4.4.1 Voltage Reference
For the purposes of IBV monitoring the user can select either the DPM’s internal voltage reference or an
external 2.5V voltage reference. The selection is made by clicking an appropriate radio button in the
DPM Type Selection window shown in Figure 14.
Figure 14. DPM Type Selection Window
The DPM’s internal 2.56V voltage reference guarantees 10% overall accuracy of the IBV protection
thresholds. If the accuracy is sufficient, the user does not need to make any changes to the schematic
shown in Figure 3. If higher accuracy of the IBV monitoring is desired, then a 2.5V external reference
ZD-00896 Rev. 5.1, 13-Jul-10
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