PT6510_08 Datasheet, PDF (5/11 Pages) Texas Instruments – 8-A Rated Output Current

Application Notes
PT6510 Series
Using the PT6510 Series as a Replacement for the
PT6500 Series in Existing Designs
Scope
The PT6510 series of power modules is the recommended
plug-in replacement for PT6500 series parts. The PT6510
series uses the same single-in-line package (SIP) outlines
and footprint as the PT6500 series, and was designed to be
functionally identical to the PT6500. This application
note highlights the differences in electrical performance
between a PT6510 series replacement compared to an
original PT6500 series part.
Overview
The features that the PT6510 series share with the
PT6500 series includes the output current rating, thermal
shutdown, and on/off standby. The input voltage range,
output voltage adjustment, and output voltage options
are also the same. In addition, applications that use the
PT6510 series as a replacement will experience a number
of performance enhancements. These include improved
efficiency and power dissipation, lower in-rush current
and output ripple voltage. The ‘off’ standby current is
also significantly reduced. Table 1-1 provides a cross
reference between the current PT6500 series part num-
bers and their equivalent PT6510 series part.
Table 1-1; PT6500 / PT6510 Series Equivalent Parts
PT6500 Series
PT6501
PT6502
PT6503
PT6504
PT6505
PT6506
V_OUT
3.3 V
1.5 V
2.5 V
3.6 V
1.2 V
1.8 V
PT6510 Series
PT6511
PT6512
PT6513
PT6514
PT6515
PT6516
Electrical and Functional Differences
Although the PT6510 series was designed as a drop-in
replacement for PT6500 series, there are minor differences
in the electrical characteristics. These are described in the
following text and should be used to assess the replace-
ment part’s compatibility with the system or end product.
A replacement part’s compatibility with the system can
be further verified with appropriate board-level tests.
On/Off Standby: The Standby input of the PT6510 series
is compatible with both the logic polarity and thresholds
of PT6500 series. One exception is the internal pull-up
voltage, which is slightly higher on the PT6510 parts.
The open-circuit voltage for the PT6510 series is the
input voltage, V_in, versus about 1 V for the PT6500 series.
This should not be a problem if the standby input is
controlled with an open-drain transistor with a sufficient
max-Vds rating.
Over-Current & Over-Temperature Protection:
To protect against short circuits and load impedance
faults, the PT6500 employs a constant output current
limit combined with over-temperature shutdown. The
PT6500 will feed a limited steady-state current into a
load fault. When limiting output current, the PT6500
exhibits higher power dissipation, which increases the
module's operating temperature. When its internal tem-
perature rises above the over-temperature threshold, the
module will shut itself down for a few seconds. The
module will then continue to periodically shut down until
the load fault is removed.
The over-current protection mechanism of the PT6510
series is different. If the output current increases above
the modules over-current threshold, its output voltage
is momentarily turned off. It then attempts to recover
by executing a soft-start power up. The module will
continue in a rapid succession of shutdowns and restarts
until the load fault is removed. During this period the
output current is not steady state, but a series of short
high-amplitude pulses (frequency <100 Hz). However,
when operating into a short-circuit load fault, the average
output current and power dissipation are significantly
lower than under normal operation.
Power-Up Characteristic: Following the application of a
valid input source, the PT6510 series modules exhibit a
slightly longer time delay than the equivalent PT6500
series part. The PT6510 series has a soft-start power-up
feature, which lowers the in-rush current at its input.
Figure 1-1 and Figure 1-2 show the power-up charac-
teristics of the PT6501 and PT6511 respectively. Both
modules have a 3.3-V regulated output, and rise to their
regulated output voltage in a similar period. Note that
the output voltage of the PT6501 begins to rise when
the input voltage reaches 2.2 V, whereas the output voltage
of the PT6511 doesn’t begin to rise until the input voltage
has reached 3.5 V.
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