zl2106 Intersil Corporation, zl2106 Datasheet - Page 25

• Manufacturer Part Number: zl2106
• Description: 6a Digital-dc Synchronous Step-down Dc-dc Converter
• Manufacturer: Intersil Corporation

If a pre-bias voltage higher than the target voltage
exists after the pre-configured delay period has
expired, the target voltage is set to match the existing
pre-bias voltage and both drivers are enabled with a
PWM duty cycle that would ideally create the pre-bias
voltage.
Once the pre-configured soft-start ramp period has
expired, the PG pin will be asserted (assuming the pre-
bias voltage is not higher than the overvoltage limit).
The PWM will then adjust its duty cycle to match the
original target voltage and the output will ramp down
to the pre-configured output voltage.
If a pre-bias voltage higher than the overvoltage limit
exists, the device will not initiate a turn-on sequence
and will declare an overvoltage fault condition to exist.
In this case, the device will respond based on the
output overvoltage fault response method that has been
selected. See Section 7.2 “Output Overvoltage
Protection,” for response options due to an overvoltage
condition.
Figure 17. Output Responses to Pre-bias Voltages
25
ZL2106
7.4 Output Overcurrent Protection
The ZL2106 can protect the power supply from
damage if the output is shorted to ground or if an
overload condition is imposed on the output. Once the
current limit threshold has been selected (see Section
6.9 “Current Limit Threshold Selection”), the user may
determine the desired course of action in response to
the fault condition. The following overcurrent
protection response options are available:
1. Initiate a shutdown and attempt to restart an
2. Initiate a shutdown and attempt to restart a preset
3. Continue operating for a given delay period,
4. Continue operating through the fault (this could
5. Initiate an immediate shutdown.
The default response from an overcurrent fault is an
immediate shutdown of the device. Please refer to
Application Note AN33 for details on how to select
specific overcurrent fault response options via
I
7.5 Thermal Overload Protection
The ZL2106 includes an on-chip thermal sensor that
continuously measures the internal temperature of the
die and will shutdown the device when the temperature
exceeds the preset limit. The factory default
temperature limit is set to 125 °C, but the user may set
the limit to a different value if desired. See Application
Note AN33 for details. Note that setting a higher
thermal limit via the I
permanent damage to the device. Once the device has
been disabled due to an internal temperature fault, the
user may select one of several fault response options as
follows:
1. Initiate a shutdown and attempt to restart an
2. Initiate a shutdown and attempt to restart a preset
2
C/SMBus.
infinite number of times with a preset delay period
between attempts.
number of times with a preset delay period
between attempts.
followed by shutdown if the fault still exists.
result in permanent damage to the power supply).
infinite number of times with a preset delay period
between attempts.
number of times with a preset delay period
between attempts.
2
C/SMBus interface may result in
Data Sheet Revision 2/19/2009
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