GE Industrial Solutions PicoTLynx 3A - Manual (Page 12)

GE
Data Sheet
PicoTLynx TM 3A: Non-Isolated DC-DC Power Modules
2.4Vdc –5.5Vdc input; 0.6Vdc to 3.63Vdc output; 3A Output Current
September 11, 2013 ©2013 General Electric Company. All rights reserved. Page 12
Output Filtering
The Pico TLynx TM 3A modules are designed for low output
ripple voltage and will meet the maximum output ripple
specification with 0.1 µF ceramic and 10 µF ceramic
capacitors at the output of the module. However, additional
output filtering may be required by the system designer for a
number of reasons. First, there may be a need to further
reduce the output ripple and noise of the module. Second,
the dynamic response characteristics may need to be
customized to a particular load step change.
To reduce the output ripple and improve the dynamic
response to a step load change, additional capacitance at
the output can be used. Low ESR ceramic and polymer
capacitors are recommended to improve the dynamic
response of the module. Figure 36 provides output ripple
information for different external capacitance values at
various Vo and for load currents of 3A while maintaining an
input voltage of 5V. Fig 37 shows the performance with a
3.3V input. For stable operation of the module, limit the
capacitance to less than the maximum output capacitance
as specified in the electrical specification table. Optimal
performance of the module can be achieved by using the
Tunable Loop feature described later in this data sheet.
0
5
10
15
20
25
30
0.5 1 1.5 2 2.5 3 3.5
Output Voltage(Volts)
R
ippl
e
(m
V
p-
p
)
1x10uF External Cap
1x47uF External cap
2x47uF External Cap
4x47uF external Cap
Figure 36. Output ripple voltage for various output
voltages with external 1x10 µF, 1x47 µF, 2x47 µF or 4x47 µF
ceramic capacitors at the output (3A load). Input voltage is
5V.
0
5
10
15
20
0.5 1 1.5 2 2.5 3
Output Voltage(Volts)
R
ippl
e
(m
V
p-
p)
1x10uF External Cap
1x47uF External cap
2x47uF External Cap
4x47uF external Cap
Figure 37. Output ripple voltage for various output voltages
with external 1x10 µF, 1x47 µF, 2x47 µF or 4x47 µF ceramic
capacitors at the output (3A load). Input voltage is 3.3V.
Safety Considerations
For safety agency approval the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standards, i.e., UL
60950-1, CSA C22.2 No. 60950-1-03, and VDE 0850:2001-12
(EN60950-1) Licensed.
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), the input must
meet SELV requirements. The power module has extra-low
voltage (ELV) outputs when all inputs are ELV.
The input to these units is to be provided with a fast-acting
fuse with a maximum rating of 5A in the positive input lead
.
Feature Descriptions
Remote On/Off
The Pico TLynx TM 3A modules feature an On/Off pin for remote
On/Off operation. Two On/Off logic options are available. In
the Positive Logic On/Off option, (device code suffix “4”- see
Ordering Information), the module turns ON during a logic
High on the On/Off pin and turns OFF during a logic Low. With
the Negative Logic On/Off option, (no device code suffix, see
Ordering Information), the module turns OFF during logic High
and ON during logic Low. The On/Off signal is always
referenced to ground. For either On/Off logic option, leaving
the On/Off pin disconnected will turn the module ON when
input voltage is present.
For positive logic modules, the circuit configuration for using
the On/Off pin is shown in Figure 38. When the external
transistor Q1 is in the OFF state, Q2 is ON, the internal PWM
Enable signal is pulled low and the module is ON. When
transistor Q1 is turned ON, the On/Off pin is pulled low, Q2 is
turned off and the internal PWM Enable signal is pulled high
through the 100K internal pull-up resistor and the module is
OFF.