ZL9010M_15 Datasheet, PDF (20/72 Pages) Intersil Corporation – Digital DC/DC PMBus 10A Power Module

ZL9010M
The routine can be set via the PMBus interface to execute one
time after ramp or periodically while regulating and have either
PG Assert behavior described earlier. Note that the Auto
Compensation feature requires a minimum t_{ON_DELAY} as
described in “Soft-start Delay and Ramp Times” on page 17.
The Auto Comp Gain control scales the Auto Comp results to
allow a trade-off between transient response and steady-state
duty cycle jitter. A setting of 100% will provide the fastest
transient response while a setting of 10% will produce the lowest
jitter.
With resistor settings, auto compensation can only be set to
execute one time after ramp with option to store auto comp
values. With auto compensation disabled, PG is asserted
according to POWER_GOOD_DELAY. With auto compensation
executed once and auto comp values not stored, PG is asserted
after auto compensation is complete at every start-up event.
With auto compensation executed once and auto comp values
stored, PG is asserted after auto compensation is complete at
the first start-up event and is asserted according to
POWER_GOOD_DELAY for subsequent start-up event along with
using the stored auto comp values from the first start-up. By
default with FC0 OPEN, auto compensation is configured to
execute one time after ramp with 70% Auto Comp Gain, PG
asserted immediately after the first Auto Comp cycle completes
and auto comp values not stored.
Note that if Auto Comp is enabled, for best results V_IN must be
stable before Auto Comp begins, as shown in Equation 4.
V^-----I^--N^--V---_N^-I--N-_o^---_m^{--- in%  -}₁^----+------2^-------15_--V----⁰⁶_----I--⁰_---N^-_----^%_----NV_--------o-O^------_m^---_{U--------T----}
(EQ. 4)
The auto compensation function can also be configured via the
AUTO_COMP_CONFIG command and controlled using the
AUTO_COMP_CONTROL command over the PMBus interface.
Please refer to “PMBus Command Summary” on page 28 for
further details.
Adaptive Diode Emulation
Adaptive diode emulation mode turns off the low-side FET gate
drive at low load currents to prevent the inductor current from
going negative, reducing the energy losses and increasing overall
efficiency. Diode emulation is available to single-phase devices
only.
Note: the overall bandwidth of the device may be reduced when
in diode emulation mode. Disabling the diode emulation prior to
applying significant load steps is recommended.
Input Undervoltage Lockout
The input undervoltage lockout (UVLO) prevents the ZL9010M
from operating when the input falls below a preset threshold,
indicating the input supply is out of its specified range.
The UVLO threshold (V_UVLO) can be set between 2.85V and 16V
using the PMBus interface.
Once an input undervoltage fault condition occurs, the device
can respond in a number of ways, as follows:
1. Continue operating without interruption.
2. Continue operating for a given delay period, followed by
shutdown if the fault still exists. The device remains in
shutdown until instructed to restart.
3. Initiate an immediate shutdown until the fault is cleared. The
user can select a specific number of retry attempts.
The default response from a UVLO fault is an immediate
shutdown of the module. The controller continuously checks for
the presence of the fault condition. If the fault condition is no
longer present, the ZL9010M is re-enabled.
Output Overvoltage Protection
The ZL9010M offers an internal output overvoltage protection
circuit that can be used to protect sensitive load circuitry from
being subjected to a voltage higher than its prescribed limits. A
hardware comparator is used to compare the actual output
voltage (seen at the FB+ pin) to a threshold set to 15% higher
than the target output voltage (the default setting). If the FB+
voltage exceeds this threshold, the PG pin deasserts and the
controller can then respond in a number of ways, as follows:
1. Initiate an immediate shutdown until the fault is cleared. The
user can select a specific number of retry attempts.
2. Turn off the high-side and the low-side MOSFETs until the
device attempts a restart.
The default response from an overvoltage fault is to immediately
shut down. The controller continuously checks for the presence
of the fault condition and when the fault condition no longer
exists, the device is re-enabled.
For continuous overvoltage protection when operating from an
external clock, the only allowed response is an immediate
shutdown.
Please refer to “PMBus Command Summary” on page 28 for
details on how to select specific overvoltage fault response
options via PMBus.
Output Prebias Protection
An output prebias condition exists when an externally applied
voltage is present on a power supply’s output before the power
supply’s control IC is enabled. Certain applications require that
the converter not be allowed to sink current during start-up if a
prebias condition exists at the output. The ZL9010M provides
prebias protection by sampling the output voltage prior to
initiating an output ramp.
If a prebias voltage lower than the target voltage exists after the
preconfigured delay period has expired, the target voltage is set
to match the existing prebias voltage and both drivers are
enabled. The output voltage is then ramped to the final
regulation value at the preconfigured ramp rate.
The actual time the output takes to ramp from the prebias
voltage to the target voltage varies, depending on the prebias
voltage, but the total time elapsed from when the delay period
expires and when the output reaches its target value, will match
the preconfigured ramp time (see Figure 20).
If a prebias voltage higher than the target voltage exists after the
preconfigured delay period has expired, the target voltage is set
to match the existing prebias voltage and both drivers are
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FN8422.2
January 22, 2015