HPH_SERIES Datasheet, PDF (8/12 Pages) Murata Manufacturing Co., Ltd. – Isolated, Low VOUT to 70A, Half-Brick DC/DC Converters

HPH Series
Isolated, Low VOUT to 70A, Half-Brick DC/DC Converters
1
-INPUT
5
+OUTPUT
6
+SENSE
3 ON/OFF
CONTROL
TRIM
-SENSE
7
R TRIM DOWN
8
4 _+INPUT
-OUTPUT ⁹
Negative: Optional negative-polarity devices are on (enabled) when the On/Off
is grounded or brought to within a low voltage (see Specifications) with respect
to –Vin. The device is off (disabled) when the On/Off is left open or is pulled
high to +Vin with respect to –Vin.
LOAD
+INPUT
4
3
ON/OFF
CONTROL
+VCC
Figure 7 – Trim adjustments to Decrease Output Voltage using a Fixed Resistor
1 _-INPUT
Radj_up ⁽ⁱⁿ kΩ) = ^{Vnominal x (1+Δ)} - ¹ - 2
1.225 x Δ Δ
where Δ =
Vout -Vnominal
Vnominal
Radj_down
(in
kΩ)
=
1
Δ
-2
where Δ =
Vnominal -Vout
Vnominal
Trim Equations
Where Vref = +1.225 Volts and Δ is the desired output voltage change. Note
that "Δ" is given as a small fraction, not a percentage.
A single resistor connected between Trim and +Sense will increase the output
voltage. A resistor connected between Trim and –Sense will decrease the output.
Remote On/Off Control
On the input side, a remote On/Off Control can be ordered with either polarity.
Positive: Standard models are enabled when the On/Off pin is left open or is
pulled high to +Vin with respect to –Vin. An internal bias current causes the
open pin to rise to +Vin. Some models will also turn on at lower intermediate
voltages (see Specifications). Positive-polarity devices are disable when the
On/Off is grounded or brought to within a low voltage (see Specifications) with
respect to –Vin.
Figure 9 – Driving the Negative Polarity On/Off Control Pin
Dynamic control of the On/Off function should be able to sink appropriate sig-
nal current when brought low and withstand appropriate voltage when brought
high. Be aware too that there is a finite time in milliseconds (see Specifications)
between the time of On/Off Control activation and stable, regulated output. This
time will vary slightly with output load type and current and input conditions.
There are three CAUTION’s for the On/Off Control:
CAUTION: To retain full output circuit isolation, control the On/Off from the input
side ONLY. If you must control it from circuits in the output, use some form of
optoisolation to the On/Off Control. This latter condition is unlikely because the
device controlling the On/Off would have to remain powered on and not be
powered from the converter..
CAUTION: While it is possible to control the On/Off with external logic if you
carefully observe the voltage levels, the preferred circuit is either an open
drain/open collector transistor or a relay (which can thereupon be controlled by
logic). The On/Off prefers to be set at +Vin (open pin) for the ON state, assum-
ing positive logic.
CAUTION: Do not apply voltages to the On/Off pin when there is no input power
voltage. Otherwise the converter may be permanently damaged.
ON/OFF CONTROL
+ Vcc
CONTROL
-INPUT
Figure 8 – Driving the Positive Polarity On/Off Control Pin
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