ZY7115 15A DC-DC Intelligent POL Data Sheet
3V to 13.2V Input 0.5V to 5.5V Output
MDS-0006 Rev. 3.8, 5-May-2011 www.power-one.com Page 22 of 33
the Turn On command was recycled, or the input
voltage was recycled.
All protections can be classified into three groups
based on their effect on system operation: warnings,
faults, and errors.
8.3.1 Warnings
This group includes Overtemperature Warning and
Power Good Signal. The warnings do not turn off
POLs but rather generate signals that can be
transmitted to a host controller via the I2C bus.
8.3.1.1 Overtemperature Warning
The Overtemperature Warning is generated when
temperature of the controller exceeds 120°C. The
Overtemperature Warning changes the PT bit of the
status register ST to 0 and sends the signal to the
DPM. Reporting is enabled in the DPM Configure
Faults window or directly via the I2C by writing into
the PC3 register shown in Figure 44. When the
temperature falls below 117°C, the PT bit is cleared
and the Overtemperature Warning is removed.
8.3.1.2 Power Good
Power Good is an open collector output that is pulled
low, if the output voltage is outside of the Power
Good window. The window is formed by the Power
Good High threshold that is equal to 110% of the
output voltage and the Power Good Low threshold
that can be programmed at 90 or 95% of the output
voltage.
The Power Good protection is only enabled after the
output voltage reaches its steady state level. The PG
pin is pulled low during transitions of the output
voltage from one level to other as shown in Figure
43.
The Power Good Warning pulls the Power Good pin
low and changes the PG bit of the status register ST
to 0. It sends the signal to the DPM, if the reporting is
enabled. When the output voltage returns within the
Power Good window, the PG pin is pulled high, the
PG bit is cleared and the Power Good Warning is
removed. The Power Good pin can also be pulled
low by an external circuit to initiate the Power Good
Warning.
Note: To retrieve status information, Status Monitoring in the DPM
Configure Devices window should be enabled (refer to
Digital Power Manager Data Sheet). The DPM will retrieve
the status information from each POL on a continuous
basis.
8.3.2 Faults
This group includes overcurrent, overtemperature,
undervoltage, and tracking protections. Triggering
any protection in this group will turn off the POL.
8.3.2.1 Overcurrent Protection
Overcurrent protection is active whenever the output
voltage of the POL exceeds the pre-bias voltage (if
any). When the output current reaches the OC
threshold, the output voltage will start decreasing. As
soon as the output voltage decreases below the
undervoltage protection threshold, the OC fault
signal is generated, the POL turns off and the OC bit
in the register ST is changed to 0. Both high side and
low side switches of the POL are turned off instantly
(fast turn-off).
The temperature compensation is added to keep the
OC threshold approximately constant at
temperatures above room temperature. Note that the
temperature compensation can be disabled in the
POL Configure Output window or directly via the I2C
by writing into the CLS register. However, it is
recommended to keep the temperature
compensation enabled.
8.3.2.2 Undervoltage Protection
The undervoltage protection is only active during
steady state operation of the POL to prevent
nuisance tripping. If the output voltage decreases
below the UV threshold and there is no OC fault, the
UV fault signal is generated, the POL turns off, and
the UV bit in the register ST is changed to 0. The
output voltage is ramped down according to
sequencing and tracking settings (regular turn-off).
8.3.2.3 Overtemperature Protection
Overtemperature protection is active whenever the
POL is powered up. If temperature of the controller
exceeds 130°C, the OT fault is generated, POL turns
off, and the OT bit in the register ST is changed to 0.
The output voltage is ramped down according to
sequencing and tracking settings (regular turn-off).
If non-latching OTP is programmed, the POL will
restart as soon as the temperature of the controller
decreases below the Overtemperature Warning
threshold of 120°C.