Ericsson Internal
PRODUCT SPEC. 2 (5)
Prepared (also subject responsible if other) No.
SEC/D KEVIN YAN 3/1301-BMR 644 4 Uen
Approved Checked Date Rev Reference
SEC/D (Wei Zhang A) 2006-02-08 A
External Ca
acitors
Input capacitors:
The recommended input capacitors are determined by the
470 μF minimum capacitance and 700 mArms minimum
ripple current rating.
Output capacitors (optional):
The recommended output capacitance of 330 μF will allow
the module to meet its transient response specification as
defined in the electrical specification.
When using one or more non-ceramic capacitors, the
calculated equivalent ESR should be no lower than 4 mΩ
(7mΩ using the manufacturer’s maximum ESR for a single
capacitor).
Input And Output Impedance
The impedance of both the input source and the load will
interact with the impedance of the DC/DC regulator. It is
important that the input source has low characteristic
impedance. The regulators 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 regulator will ensure stable operation.
The capacitor is not required when powering the DC/DC
regulator 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 b
addition of decouplin
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.
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.
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 regulator 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.
For further information please contact your local Ericsson
Power Modules representative.
Output Voltage Adjust (Vadj)
The DC/DC regulators have an Output Voltage Adjust pin
(Vadj). This pin can be used to adjust the output voltage above
or below Output voltage initial setting.
To increase or decrease the voltage the resistor should be
connected between the Vadj pin and GND pin. The resistor
value of the Output voltage adjust function is according to
information given under the Output section for the respective
product.
Parallel Operation
Two regulators may be paralleled for redundancy if the total
power is equal or less than PO max. It is not recommended to
parallel the regulators without using external current sharing
circuits.
Remote Sense
The DC/DC regulators have remote sense that can be used to
compensate for voltage drops between the output and the
point of load. The sense traces should be located close to the
PCB ground layer to reduce noise susceptibility. The remote
sense circuitry will compensate for up to 0.3v voltage drop
between output pins and the point of load.
If the remote sense is not needed +Sense should be left
open.
Over Current Protection (OCP)
The regulators include current limiting circuitry for protection
at continuous overload.
The output voltage will decrease towards zero for output
currents in excess of the over-current threshold. The regulator
will resume normal operation after removal of the overload.
The load distribution should be designed for the maximum
output short circuit current specified. The current limit
operation is a “hick up” mode current limit.
PMG 4000 series
POL regulator, Input 2.95-3.65 V, Output 15 A/37.5 W
EN/LZT 146 319 R1B April 2006
© Ericsson Power Modules AB