PI3740-00 Datasheet, PDF (21/48 Pages) Vicor Corporation – Parallel capable with single wire current sharing

Output Overvoltage Protection
The PI3740-00 is equipped with two methods of detecting
an output over voltage condition. To prevent damage to input
voltage sensitive devices, if the output voltage exceeds 20% of
its set regulated value as measured by the EAIN pin (V_{EAIN_OV}),
the regulator will complete the current cycle, stop switching and
issue an OVP fault. Also if the output voltage of the regulator
exceeds the V_OUT Overvoltage Threshold (V_{OUT_OVT}) then the
regulator will complete the current cycle, stop switching and
issue an OVP fault. The system will resume operation once
the output voltage falls below the OVP threshold and after
Fault Restart Delay.
Overtemperature Protection
The PI3740-00 features an over temperature protection (OTP),
which will not engage until after the product is operated
above the maximum rated temperature. The OTP circuit is only
designed to protect against catastrophic failure due to excessive
temperatures and should not be relied upon to ensure the device
stays within the recommended operating temperature range.
Thermal shutdown terminates switching and discharges the
soft-start capacitor. As the temperature falls the PI3740-00 will
restart, and this will always occur before the product returns to
rated temperature range.
Pulse Skip Mode (PSM)
PI3740-00 features a hysteretic Pulse Skip Mode to achieve high
efficiency at light loads. The regulator is setup to skip pulses if
V_EAO falls below the Pulse Skip Threshold (V_{EAO_PST}). Depending
on conditions and component values, this may result in single
pulses or several consecutive pulses followed by skipped pulses.
Skipping cycles significantly reduces gate drive power and
improves light load efficiency. The regulator will leave Pulse Skip
Mode once the control node rises above the Pulse Skip Mode
threshold (V_{EAO_PST}).
Variable Frequency Operation
The PI3740-00 is preprogrammed to a fixed, maximum, base
operating frequency. The frequency is selected with respect to
the required power stage inductor to operate at peak efficiency
across line and load variations. The switching frequency period
will stretch as needed during each cycle to accommodate low
line and or high load conditions. By stretching the switching
frequency period, thus decreasing the switching frequency, the
ZVS operation is preserved throughout the input line voltage
range maintaining optimum efficiency.
IMON Amplifier
The PI3740-00 provides a differential amplifier with a level
shifted, SGND referenced output, the IMON Pin, which is useful
for sensing input or output current on high voltage rails. A fixed
gain of 20:1 is provided over a large common mode range.
When using the amplifier, the ISN pin must be referenced to
the common mode voltage of the ISP pin for proper operation.
See Absolute Maximum Ratings for more information. If not in
use, the ISN and ISP pins should be connected to SGND and the
IMON pin left floating.
Cool-Power^® ZVS Switching Regulators
Page 21 of 48
Rev 1.4
04/2017
vicorpower.com
800 927.9474
PI3740-00