Operating information
Output Voltage Adjust (Vadj
)
The utput voltage, VO, can be adjusted by using an external resistor. A
0.1 MW resistor will change VO approximately 5ꢀ. 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).
Remote Control (RC)
Remote turn-on and turn-off can be realized by using the RC-pin.
Normal operation is achieved if pin 1 is open (NC). If pin 1 is con-
nected to pin 3 the PKG power module turns off. To ensure safe turn-
off the voltage difference between pin 1 and 3 shall be less than 1.0 V.
RC is TTL open collector compatible (see fig. 1).
Maximum Capacitive Load
The PKG series has no limitation of maximum connected capacitance
on the output. The power module may operate in current limiting
mode during start-up, affecting the ramp-up and the start-up time.
For optimum performance we recommend maximum 100 mF/A of IO
for dual outputs. Connect capacitors at the point of load for best per-
formance.
PKG
RC (pin 1)
TTL
Parallel Operation
-In (pin 3)
The load regulation characteristic and temperature coefficient of the
PKG DC/DC Power Modules are designed to allow parallel operation.
Paralleling of several modules is easily accomplished by connection of
the output voltage terminal pins. The connections should be symmet-
rical, i.e. the resistance between the output terminal and the common
connection point of each module should be equal. Good paralleling
performance is achieved if you allow the resistance to be 10 mW.
10 mW equals 50 mm (2 in) of 35 mm (1 oz/ft2) copper with a trace
width of 2.5 mm (0.1 in).
It is recommended not to exceed PO =n × 0.8 × POmax, where POmax
is the maximum power module output power and n the number of
paralleled units, not to overload any of them and thereby decrease the
reliability performance.
Fig. 1
Over Voltage Protection (OVP)
The PKG series has an internal Over Voltage Protection circuitry. The
circuitry will detect over voltage conditions on the output and stop
the power module operation. During OVP conditions there are contin-
uous attempts to start up (non-latching mode). If latching mode is
preferred an external circuit can be used to change the function and
make the output remain in off mode after over voltage detection. (The
OVP level can be found in the output data section.)
Paralleling performance may be further improved by voltage match-
ing. Voltage matching is accomplished by using the Output Adjust
function and trim the outputs to the same voltage.
+VI (pin 4)
Current Limiting Protection
62k
Reset
The output power is limited at loads above the output current limit-
ing threshold (Ilim), specified as a minimum value.
6.8k
RC (pin 1)
22k
1k
Input and Output Impedance
10k
10k
2.7 V
Both the source impedance of the power feeding and the load imped-
ance will interact with the impedance of the DC/DC power module.
It is most important to have the ratio between L and C as low as possi-
ble, i.e. a low characteristic impedance, both at the input and output,
as the power modules have a low energy storage capability.
10mF
-VI (pin 3)
Use an electrolytic capacitor across the input or output if the source or
load inductance is larger than 10 mH. Their equivalent series resistance
together with the capacitance acts as a lossless damping filter. Suitable
capacitor values are in the range 10–100 mF.
Fig. 2
Turn-on/off Input Voltage (TOA)
The power module monitors the input voltage and will turn on and
turn off at predetermined levels. The levels can be decreased by means
of an external resistor connected between pin 2 and pin 4.
A 0.2 MW resistor will decrease the turn-off input voltage approxi-
mately 10ꢀ.
EN/LZT 146 03 R1A (Replaces EN/LZT 137 R5) ©Ericsson Microelectronics AB, May 2000
12
ERICSSON [ ERICSSON ]
