Over Voltage Protection (OVP)
EMC Specifications
The remote control can also be utilized for OVP by using the external
circuitry in fig. 2. Resistor values given are for 5V output applica-
tions, but can easily be adjusted for other output voltages and the
desired OVP level.
The conducted EMI measurement was performed using a module
placed directly on the test bench.
The fundamental switching frequency is 300 kHz 15ꢀ @ V = 26V,
I
IO = (0.1...1.0) ×IOmax.
Conducted EMI Input terminal value (typ)
5
4
6
7
9
8
1
10
3
Fig. 2
Maximum Capacitive Load
The maximum recommended capacitance connected directly to the
PKA DC/DC power modules’ output, without resistance or inductance
in series, is 100 mF/A (output current rating). Connect capacitors
across the load for maximum effectiveness and maximum stability
margins.
Turn-off Input Voltage (VIoff
)
5
50
The input voltage is monitored and the PKA DC/DC power module
will turn on and turn off at predetermined levels. The levels can be
decreased by means of an external resistor connected between pin 1
and pin 4.
A 200 kW resistor will decrease the shutdown voltage below 18 V. To
maintain the nominal output voltage at input voltages below VI min it
may be necessary to decrease the load.
Test Set-up according to CISPR publ. 1A.
Output Ripple (VOac)
Output ripple is measured as the peak to peak voltage of the funda-
mental switching frequency.
Output Voltage Adjust (Vadj
)
The output voltage, VO, can be adjusted by using an external resistor.
The output voltage adjust function is not accurate and it is recom-
mended to use a potentiometer. To decrease the output voltage the
resistor should be connected between pin 10 and pin 9 (+Out 1). To
increase the output voltage the resistor should be connected between
pin 10 and pin 8 (–Out 1).
Operating information
Remote Control (RC)
Turn-on or turn-off can be realized by using the RC-pin. Normal
operation is achieved if pin 1 is open (NC). If pin 1 is connected to pin
3 the PKA DC/DC power module turns off. To ensure safe turn-off the
voltage difference between pin 1 and 3 shall be less than 1.8 V. RC is
TTL open collector compatible (see fig. 1). Pin 1 is an output and no
current should be driven into pin 1. Use a diode if necessary e.g. totem
pole TTL logic. The internal pull-up resistance is 36 kW.
Parallel Operation
Due to the current limiting protection (hick-up), temperature coeffi-
cient and output voltage characteristic for PKA paralleling of modules
for increased power is not recommended. PKA can be paralleled for
redundancy.
+V
I
PKA
Current LimitingProtection
RC
(pin 1)
The output power is limited at loads above the output current limiting
threshold (Ilim), specified as a minimum value.
TTL
Control
Logic
As the PKA multiple output models are power limited, current limit-
ing threshold for an individual output is set by the loads on the other
outputs. The power module can withstand continuous short circuit
without destruction. A hick-up mode is used on all models to mini-
mize the internal power dissipation. The hick-up time constant is set
by the slow start.
-In
(pin 3)
-V
I
Fig. 1
EN/LZT 146 09 R1A © Ericsson Microelectronics AB, June 2000
15
ERICSSON [ ERICSSON ]
