Ericsson Internal
EJUNGYA
PRODUCT SPECIFICATION
2 (5)
Prepared (also subject responsible if other)
No.
3/1301-BMR 636 01/A4 Uen
9
Technical Specification
Approved
Checked
Date
Rev
Reference
EN/LZT 146 382 R1A June 2007
PKB 4717 PINB
DC/DC converters, Input 36-75 V, Output 10.5 A/75 W
SEC/D (Julia You)
ECHWANG 2007-6-18
A
© Ericsson Power Modules AB
The ceramic capacitors will handle high-frequency dynamic
load changes while the electrolytic capacitors are used to
handle low frequency dynamic load changes. Ceramic
capacitors will also reduce any high frequency noise at the
load.
Operating information
Input Voltage
The input voltage range 36 to 75Vdc meets the requirements
{of the European Telecom Standard ETS 300 132-2 for
normal input voltage range in —48 and —60 Vdc systems, -40.5
to -57.0 V and —50.0 to -72 V respectively.
At input voltages exceeding 75 V, the power loss will be
higher than at normal input voltage and Tref must be limited to
absolute max +110°C. The absolute maximum continuous
input voltage is 80 Vdc.
It is equally important to use low resistance and low
inductance PCB layouts and cabling.
External decoupling capacitors will become part of the
control loop of the DC/DC converter and may affect the
stability margins. As a “rule of thumb”, 100 μF/A of output
current can be added without any additional analysis. The
ESR of the capacitors is a very important parameter. Power
Modules guarantee stable operation with a verified ESR value
of >10 mΩ across the output connections.
Turn-off Input Voltage
For further information please contact your local Ericsson
Power Modules representative.
The DC/DC converters monitor the input voltage and will turn
on and turn off at predetermined levels.
The minimum hysteresis between turn on and turn off input
voltage is 1V.
Output Voltage Adjust (Vadj
)
The DC/DC converters have an Output Voltage Adjust pin
(Vadj). This pin can be used to adjust the output voltage above
or below Output voltage initial setting.
When increasing the output voltage, the voltage at the output
pins (including any remote sense compensation ) must be
kept below the threshold of the over voltage protection, (OVP)
to prevent the converter from shutting down. At increased
output voltages the maximum power rating of the converter
remains the same, and the max output current must be
decreased correspondingly.
To increase the voltage the resistor should be connected
between the Vadj pin and +Sense pin. The resistor value of the
Output voltage adjust function is according to information
given under the Output section for the respective product.
To decrease the output voltage, the resistor should be
connected between the Vadj pin and —Sense pin.
Remote Control (RC)
The products are fitted with a
remote control function referenced
to the primary negative input
connection (- In), with negative
logic option available. The RC
function allows the converter to be
turned on/off by an external device
like a semiconductor or mechanical
switch. The RC pin has an internal
pull up resistor to + In.
The maximum required sink current is 1 mA. When the RC pin
is left open, the voltage generated on the RC pin is
12 — 15 V.
See Design Note 021 for detailed information.
Input and Output Impedance
The impedance of both the input source and the load will
interact with the impedance of the DC/DC converter. It is
important that the input source has low characteristic
impedance. The converters are designed for stable operation
without external capacitors connected to the input or output.
The performance in some applications can be enhanced by
addition of external capacitance as described under External
Decoupling Capacitors. If the input voltage source contains
significant inductance, the addition of a 100 μF capacitor
across the input of the converter will ensure stable operation.
The capacitor is not required when powering the DC/DC
converter from an input source with an inductance below
10 μH.
External Decoupling Capacitors
When powering loads with significant dynamic current
requirements, the voltage regulation at the point of load can
be improved by addition of decoupling capacitors at the load.
The most effective technique is to locate low ESR ceramic
and electrolytic capacitors as close to the load as possible,
using several parallel capacitors to lower the effective ESR.
ERICSSON [ ERICSSON ]
