Functional Description:
Input Power Pins IN(+) and IN(-):
than 2.35V typical, the converter will be held off or
shut down if already operating. A third feature is
offered in that during a fault condition such as output
OVP, input UV or OV, or output current limit, the
ENABLE pin is pulled low internally. This can be
used as a signal to the user that a fault has
occurred. Whenever the ENABLE pin is pulled low,
the TRIM/SS pin follows, resetting the internal and
external soft-start circuitry. All faults will pull
ENABLE low including over temperature. If
increased turn on delay is desired, the ENABLE pin
can be bypassed with a small capacitor up to a
maximum of 1500pF.
The input power pins on the PI3106-00-HVMZ are
connected to the input power source which can
range from 16V to 50V DC. Under surge conditions,
the PI3106-00-HVMZ can withstand up to 55V DC
for 12.5 ms without incurring damage. The user
should take care to avoid driving the input rails
above the specified ratings. Since the PI3106-00-
HVMZ is designed with high reliability in mind, the
input pins are continuously monitored. If the applied
voltage exceeds the input over-voltage trip point
(typically 53.5V) the conversion process shall be
terminated immediately. The converter initiates soft-
start automatically within 80ms after the input
voltage is reduced back to the appropriate value.
The input pins do not have reverse polarity
protection. If the PI3106-00-HVMZ is operated in an
environment where reverse polarity is a concern, the
user should consider using a polarity protection
device such as a suitably rated diode. To avoid the
high losses of using a diode, the user should
consider the much higher efficiency Picor family of
intelligent Cool-ORing® solutions that can be used in
reverse polarity applications. Information is available
at picorpower.com.
TRIM/SS Pin:
The TRIM/SS pin serves as another multi-purpose
pin. First, it is used as the reference for the internal
error amplifier. Connecting a resistor from TRIM/SS
to SGND allows the reference to be margined down
by as much as -20%. Connecting a resistor from
TRIM/SS to ENABLE will allow the reference and
output voltage to be margined up by 10%. If the user
wishes a longer start up time, a small ceramic
capacitor can be added to TRIM/SS to increase it. It
is critical to connect any device between TRIM/SS
and SGND and not -IN, otherwise high frequency
noise will be introduced to the reference and
possibly cause erratic operation.
The PI3106-00-HVMZ will draw nearly zero current
until the input voltage reaches the internal start up
threshold. If the ENABLE pin is not pulled low by
external circuitry, the output voltage will begin rising
to its final value of 12V about 80ms after the input
UV lockout releases. This will occur automatically
even if the ENABLE pin is floating.
TM Pin:
The TM pin serves as an output indicator of the
internal package temperature which is within
approximately +/- 5 K of the hottest junction
temperature. Because of this, it is a good indicator of
a thermal overload condition. The output is a scaled,
buffered analog voltage which indicates the internal
temperature in degrees Kelvin. Upon a thermal
overload, the TM pin is pulled low, indicating a
thermal fault has occurred. Upon restart of the
converter, the TM pin reverts back to a buffered
monitor. The thermal shutdown function of the
PI3106-00-HVMZ is a fault feature which interrupts
power processing if a certain maximum temperature
is exceeded. TM can be monitored by an external
microcontroller or circuit configured as an adaptive
fan speed controller so that air flow in the system
can be conveniently regulated.
To help keep the source impedance low, the input to
the PI3106-00-HVMZ should be bypassed with (2)
4.7uF 50V ceramic capacitors of X7R dielectric in
parallel with a low Q 100uF 63V electrolytic
capacitor. To reduce EMI and reflected ripple
current, a series inductor of 0.2 to 0.47uH can be
added. The input traces to the module should be low
impedance configured in such a manner as to keep
stray inductance minimized.
ENABLE Pin:
The ENABLE pin serves as a multi-function pin for
the PI3106-00-HVMZ. During normal operation, it
outputs the on-board 4.9V regulator which can be
used for trimming the module up. The ENABLE pin
can also be used as a remote enable pin either from
the secondary via an optocoupler and some external
isolated bias supply or from the primary side through
a small signal transistor, FET or any device that
sinks 3.3mA, minimum. If the ENABLE pin is lower
SGND Pin:
The PI3106-00-HVMZ SGND pin is the “quiet”
control circuitry return. It is basically an extension of
the internal signal ground. To avoid contamination
and potential ground loops, this ground should NOT
be connected to -IN since it is already star
Picor Corporation • picorpower.com
Preliminary PI3106-00-HVMZ Rev 1.3, Jan 17th, 2012 Page 7 of 15
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