unr-3.3-3000-d5 Murata Manufacturing Co., Ltd, unr-3.3-3000-d5 Datasheet - Page 4

• Manufacturer Part Number: unr-3.3-3000-d5
• Description: Single Output, Non-isolated, 3.3v 8-40 Watt, Dc/dc Converters
• Manufacturer: Murata Manufacturing Co., Ltd

Technical Notes
Input Capacitors
As shown in the simplified schematic, UNR Series power converters do not
have internal input capacitors. Users must install external input capacitors for
the devices to achieve specified operation. The input capacitor functions as a
true energy-storage element. Its required capacitance varies as a function of
applied line voltage. Additionally, as the power converter’s input FET switch
cycles on and off, the input capacitor must have the ability to rapidly supply
pulses of relatively high current. Therefore, required rms-ripple-current capa-
bilities of the input capacitor will vary as a function of the power converter’s
load current. Rather than install a large, expensive, internal capacitor that
UNR-3.3/12000-D5
UNR-3.3/8000-D5
UNR-3.3/3000-D5
10000
10000
1000
1000
1000
100
100
100
10
4.75
4.75
4.75
4.80
4.80
4.80
4.85
4.85
4.85
4.90
4.90
4.90
Minimum Input Capacitor Value vs. V
Minimum Input Capacitor Value vs. V
Minimum Input Capacitor Value vs. V
4.95
4.95
4.95
5.00
5.00
5.00
Input Voltage (Volts)
Input Voltage (Volts)
Input Voltage (Volts)
5.05
5.05
5.05
www.murata-ps.com
5.10
5.10
5.10
5.15
5.15
5.15
5.20
5.20
5.20
IN
IN
IN
5.25
5.25
5.25
@ Full Load
@ Full Load
@ Full Load
5.30
5.30
5.30
5.35
5.35
5.35
5.40
5.40
5.40
addresses all possible load conditions, we have chosen to leave the capaci-
tor out so that you may select a cost-effective component appropriate to your
particular application.
Use the charts below to determine how much input capacitance is required
as a function of input voltage and also to determine the required rms-ripple-
current capabilities of the needed capacitor as a function of output load
current. Note that "low-line" conditions will require proportionally more input
capacitance in order to maintain the required energy levels and that higher
output currents will obviously require higher input currents. Contact DATEL’s
Applications Engineering Group if you have any questions.
5.45
5.45
5.45
5.50
5.50
5.50
1.75
1.50
1.25
0.75
0.50
0.25
3.5
2.5
1.5
0.5
8
7
6
5
4
3
2
1
0
4
3
2
1
0
2
1
0
Technical enquiries email: [e-mail], tel:
0.3
1
1
2
0.6
2
Single Output, Non-Isolated, 3.3V
3
C
C
C
0.9
Output Load Current (Amps)
IN
Output Load Current (Amps)
IN
Output Load Current (Amps)
IN
8-40 Watt, DC/DC Converters
RMS Ripple Current vs. I
RMS Ripple Current vs. I
RMS Ripple Current vs. I
4
3
1.2
5
4
1.5
6
7
1.8
MDC_UNR8-40W.B01 Page 4 of 6
5
UNR Series
8
2.1
6
LOAD
9
LOAD
LOAD
2.4
10
7
[phone]
2.7
11
3.0
12
8