pth12040 Astec Powe, pth12040 Datasheet - Page 7

• Manufacturer Part Number: pth12040
• Description: Pth12040 12vin Single
• Manufacturer: Astec Powe

5. Safety Information
5.1 Safety Standards and Approvals
All models will have full international safety approval including
EN60950 and UL/cUL1950. Models have been submitted to
independent safety agencies for approval.
5.2 Fuse Information
Any suitable value fuse (based on the input ratings) maybe used in
the unearthed input line. However this is not required for compliance
with safety.
5.3 Safety Considerations
The converter must be installed as per guidelines outlined by the
various safety agency approvals, if safety agency approval is
required for the overall system.
File Name: an_pth12040.pdf Rev (02): 21 Dec 2005
6. Operating Information
6.1 Overtemperature Protection (OTP)
Only the PTHxx020 and PTHxx030 and PTHxx040 series of products
have overtemperature protection. These products have an on-board
temperature sensor that protects the module’s internal circuitry
against excessively high temperatures. A rise in the internal
temperature may be the result of a drop in airflow, or a high ambient
temperature. If the internal temperature exceeds the OTP threshold
(see datasheet specifications), the module’s Inhibit control is
automatically pulled low. This disables the regulator allowing the
output voltage to drop to zero. (The external output capacitors will
be discharged by the load circuit). The recovery is automatic, and
begins with a soft-start power-up. It occurs when the the sensed
temperature decreases by about 10°C below the trip point.
Note: The overtemperature protection is a last resort mechanism to
prevent thermal stress to the regulator. Operation at or close to the
thermal shutdown temperature is not recommended and will reduce
the long-term reliability of the module. Always operate the regulator
within the specified Safe Operating Area (SOA) limits for the worst-
case conditions of ambient temperature and airflow.
6.2 Overcurrent Protection
For protection against load faults, all modules incorporate output
overcurrent protection. Applying a load that exceeds the regulator’s
overcurrent threshold will cause the regulated output to shut down.
Following shutdown a module will periodically attempt to recover by
initiating a soft-start power-up. This is described as a “hiccup” mode
of operation, whereby the module continues in the cycle of
successive shutdown and power-up until the load fault is removed.
During this period, the average current flowing into the fault is
significantly reduced. Once the fault is removed, the module
automatically recovers and returns to normal operation.
6.3 Soft-start Power-up
The Auto-Track feature allows the power-up of multiple PTH modules
to be directly controlled from the Track pin. However in a stand-alone
configuration, or when the Auto-Track feature is not being used, the
Track pin should be directly connected to the input voltage, Vin (see
Figure 5).
When the Track pin is connected to the input voltage the Auto-Track
function is permanently disengaged. This allows the module to
power-up entirely under the control of its internal soft-start circuitry.
When power-up is under soft-start control, the output voltage rises
to the set-point at a quicker and more linear rate.
Application Note 193
C
1000µF
in
GND
12V
www.artesyn.com
+
2
V
Figure 5 - Soft-start Power-up
Inhibit
in
Up
10
3
Dn
9
GND
1
PTH12020W
Track
8
7
Adjust
Sense
4
R
0.1W, 1%
V
5
set
out
1.5kΩ
6
+
C
330µF
out
GND
3.3V
7