ZL9006M
FN7959 Rev 2.00 Page 21 of 69
March 16, 2016
Output Overcurrent Protection
The ZL9006M can protect the power supply from damage if the
output is shorted to ground or if an overload condition is imposed
on the output. The following overcurrent protection response
options are available:
1. Initiate a shutdown and attempt to restart an infinite number
of times with a preset delay period between attempts.
2. Initiate a shutdown and attempt to restart a preset number of
times with a preset delay period between attempts.
3. Continue operating for a given delay period, followed by
shutdown if the fault still exists.
4. Continue operating through the fault (this could result in
permanent damage to the power supply).
5. Initiate an immediate shutdown.
The default response from an overcurrent fault is an immediate
shutdown of the controller. The controller continuously checks for
the presence of the fault condition, and if the fault condition no
longer exists, the device is re-enabled.
Please refer to “PMBus Commands Description” on page 32 for
details on how to select specific overcurrent fault response
options via PMBus.
Thermal Overload Protection
The ZL9006M includes a thermal sensor that continuously
measures the internal temperature of the module and shuts
down the controller when the temperature exceeds the preset
limit. The default temperature limit is set to +125°C in the
factory, but the user may set the limit to a different value if
desired. See “PMBus Commands Description” on page 32 for
details. Note that setting a higher thermal limit via the PMBus
interface may result in permanent damage to the controller.
Once the module 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 infinite number
of times with a preset delay period between attempts.
2. Initiate a shutdown and attempt to restart a preset number of
times with a preset delay period between attempts.
3. Continue operating for a given delay period, followed by
shutdown if the fault still exists.
4. Continue operating through the fault (this could result in
permanent damage to the power supply).
5. Initiate an immediate shutdown.
If the user has configured the module to restart, the controller
waits the preset delay period (if configured to do so) and then
checks the module temperature. If the temperature has dropped
below a threshold that is approximately +15°C lower than the
selected temperature fault limit, the controller attempts to
restart. If the temperature still exceeds the fault limit, the
controller waits the preset delay period and retries again.
The default response from a temperature fault is an immediate
shutdown of the module. The controller continuously checks for
the fault condition, and once the fault has cleared, the ZL9006M
is re-enabled.
Please refer to “PMBus Commands Description” on page 32 for
details on how to select specific temperature fault response
options via PMBus.
Voltage Tracking
Numerous high performance systems place stringent demands
on the order in which the power supply voltages are turned on.
This is particularly true when powering FPGAs, ASICs, and other
advanced processor devices that require multiple supply voltages
to power a single die. In most cases, the I/O interface operates at
a higher voltage than the core and therefore the core supply
voltage must not exceed the I/O supply voltage according to the
manufacturers' specifications. Voltage tracking protects these
sensitive ICs by limiting the differential voltage between multiple
power supplies during the power-up and power down sequence.
The ZL9006M integrates a lossless tracking scheme that allows
its output to track a voltage that is applied to the VTRK pin with
no external components required. The VTRK pin is an analog
input that, when tracking mode is enabled, configures the
voltage applied to the VTRK pin to act as a reference for the
device’s output regulation. Figure 22 illustrates the typical
connection of two tracking modules.
The ZL9006M offers two modes of tracking as follows, and can
be configured according to an external resistor, RSS, connected
between SS and SGND in Table 10 or via PMBus. The tON_DELAY
time is set to 5ms, and tOFF_DELAY time is set to 35ms. The
RAMP time is set to 2ms, but can track to a slower RAMP time,
i.e., >2ms.
1. Coincident. This mode configures the module to ramp its
output voltage at the same rate as the voltage applied to the
VTRK pin. Two options are available for this mode:
- Track at 100% VOUT limited. Member rail tracks the
reference rail and stops when the member reaches its target
voltage (Figure 23A).
- Track at 100% VTRK limited. Member rail tracks the
reference at the instantaneous voltage value applied to the
VTRK pin (Figure 23B).
TABLE 10. TRACKING RESISTOR SETTINGS
RSS
(kΩ)
TRACK
RATIO
(%)
UPPER TRACK
LIMIT RAMP-UP/DOWN BEHAVIOR
90.9 100 Limited by target Output does not decrease
before PG
100 Output always follows VTRK
110 Limited by VTRK Output does not decrease
before PG
121 Output always follows VTRK
133 50 Limited by target Output does not decrease
before PG
147 Output always follows VTRK
162 Limited by VTRK Output does not decrease
before PG
178 Output always follows VTRK