
Ericsson Internal
PRODUCT SPEC.
3 (5)
Prepared (also subject responsible if other)
No.
SEC/D KEVIN YAN
3/1301-BMR 651 8 Uen
Approved
Checked
Date
Rev
Reference
SEC/D Wei Zhang A
2006-3-6
PA1
Over Temperature Protection (OTP)
The PMM family of POL regulators are protected from thermal
overload by an internal over temperature shutdown circuit.
When the internal temperature exceeds the OTP threshold,
the POL regulator will shut down. The POL regulator will
make continuous attempts to start up (soft-start mode) and
resume normal operation automatically when the temperature
has dropped >10°C below the temperature threshold.
Over Current Protection (OCP)
The POL 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.
Soft-start Power Up
From the moment a valid input voltage is applied, the soft-
start control introduces a short time-delay (typically 8-15 ms)
before allowing the output voltage to rise.
The initial rise in input current when the input voltage first
starts to rise is the charge current drawn by the input
capacitors. Power-up is complete within 25 ms.
Auto-Track Function
The AutoTrack function is designed so that 2 or more POL
regulators can track each others output voltage tightly
together. This can be accomplished by connection the
AutoTrack pin to the output of another POL regulator or by
feeding an external voltage ramp on the pin. The AutoTrack
will automatically track any external voltage that is applied
within the given rules in Application Note POLA (AN205).
Margin Up/Down controls
The margin control allows the input voltage to be momentarily
adjusted, either up or down, by a nominal 5 %. This provides
a convenient method for dynamically testing the operation of
the load circuit over its supply margin or range. It can also be
used to verify the function of supply voltage supervisors.
Pre-Bias Startup Capability
This often occurs in complex digital systems when current
from another power source is backfed through a dual-supply
logic component, such as FPGA or ASIC.
The PMM family incorporate synchronous rectifiers, but will
not sink current during startup, or whenever the Inhibit pin is
held low. However, to ensure satisfactory operation of this
function, certain conditions must be maintained.
Thermal Consideration
General
The POL regulators are designed to operate in different
thermal environments and sufficient cooling must be provided
to ensure reliable operation.
Cooling is achieved mainly by conduction, from the pins to
the host board, and convection, which is dependant on the
airflow across the regulator. Increased airflow enhances the
cooling of the POL regulator.
The Output Current Derating graph found in the Output
section for each model provides the available output current
vs. ambient air temperature and air velocity at Vin = 12 V.
The POL regulator is tested on a 254 x 254 mm,
35 m (1 oz), 8-layer test board mounted vertically in a wind
tunnel with a cross-section of 305 x 305 mm.
Proper cooling of the POL regulator can be verified by
measuring the temperature at positions P1, P2 and P3. The
temperature at these positions should not exceed the max
values provided in the table below.
Note that the max value is the absolute maximum rating
(non destruction) and that the electrical Output data is
guaranteed up to Tamb +85°C.
See Design Note 019 for further information.
Position
Device
Designation
max value
P1
Pcb
130 C
P2
Mosfet
Tref
130 C
P3
Inductor
130 C
E
PMM 8000 series
POL regulator, Input 8-14 V, Output 50 A/275 W
EN/LZT 146 339 R1A April 2006
Ericsson Power Modules AB
Technical Specication
E
PMM 8000 series
POL regulator, Input 8-14 V, Output 50 A/275 W
EN/LZT 146 339 R1A April 2006
Ericsson Power Modules AB
Technical Specication
E
PMM 8000 series
POL regulator, Input 8-14 V, Output 50 A/275 W
EN/LZT 146 339 R1A April 2006
Ericsson Power Modules AB
Technical Specication
28