YH09T40 40A DC-DC POL Converter
5V to 13.8V Input
0.6V to 3.63V Output
Data Sheet
ZD-02095 Rev. 1.1, 18-Jun-10 www.power-one.com Page 11 of 13
6.5.2 Input Undervoltage Lockout
The POL converter will shut down when the input
voltage drops below a predetermined voltage. It will
start automatically when the input voltage exceeds
the specified threshold.
6.5.3 Output Overcurrent Protection
The POL converter is protected against overcurrent
and short circuit conditions. Upon sensing an
overcurrent condition, the POL converter will enter
hiccup mode of operation. Once the overload or
short circuit condition is removed, the POL converter
will automatically restart and Vout will return to its
nominal value.
6.5.4 Output Overvoltage Protection
The POL converter is protected against overvoltage
on the output. If the output voltage is higher than
125% of its nominal value set by the R
TRIM
, the high
side MOSFTES will be immediately turned off and
the low side MOSFETs will be turned on. The POL
converter will remain in the state until the output
voltage reduces below 115% of its nominal value. At
that point the POL converter will automatically
restart.
6.5.5 Overtemperature Protection
The POL converter will shut down under an
overtemperature condition to protect itself from
overheating caused by operation outside the thermal
derating curves, or operation in abnormal conditions
such as system fan failure. After the POL converter
has cooled to a safe operating temperature, it will
automatically restart.
7. Characterization
7.1 Ripple and Noise
The output voltage ripple and input reflected ripple
current waveforms are measured using the test
setup shown in Figure 20.
Figure 20. Test Setup For Measuring Input Reflected-Ripple
Current
And Output Voltage Ripple
8. Safety
The YH09T40-0 POL converters do not provide
isolation from input to output. The input devices
powering YH09T40-0 must provide relevant isolation
requirements according to all IEC60950 based
standards. Nevertheless, if the system using the
converter needs to receive safety agency approval,
certain rules must be followed in the design of the
system. In particular, all of the creepage and
clearance requirements of the end-use safety
requirements must be observed. These
requirements are included in UL60950 - CSA60950-
00 and EN60950, although specific applications may
have other or additional requirements.
The YH09T40-0 POL converters have no internal
fuse. If required, the external fuse needs to be
provided to protect the converter from catastrophic
failure. Refer to the “Input Fuse Selection for DC/DC
converters” application note on www.power-one.com
for proper selection of the input fuse. Both input
traces and the chassis ground trace (if applicable)
must be capable of conducting a current of 1.5 times
the value of the fuse without opening.
To comply with safety agencies’ requirements, a
recognized fuse must be used in series with the input
line. The fuse must not be placed in the grounded
input line. Abnormal and component failure tests
were conducted with the POL input protected by
three fast-acting 15A, 125V fuses connected in
parallel. If fuses rated greater than 15A is used,
additional testing may be required.
The maximum DC voltage between any two pins is
Vin under all operating conditions. In order for the
output of the YH09T40-0 POL converter to be
considered as SELV (Safety Extra Low Voltage),
according to all IEC60950 based standards, the input
to the POL needs to be supplied by an isolated
secondary source providing a SELV also.
out
S
source
470µF
capacitor
1.0
H
source
inductance
C
IN
100µF
tantalum
+
47
F
ceramic
capacito
YH09T40
