
A
1 Watt SIP Dual Series DC/DC Converters
2401 Stanwell Drive Concord, California 94520 Ph: 925/687-4411 or 800/542-3355 Fax: 925/687-3333 www.calex.com Email: sales@calex.com
4
3/2001
0
10
2030
405060
7080
90
100
LOAD (%)
50
55
60
65
70
75
80
EFFICIENCY
(%)
EFFICIENCY Vs. LOAD
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (VDC)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
INPUT
CURRENT
(AMPS)
INPUT CURRENT Vs. INPUT VOLTAGE
from ambient by knowing that the case temperature rise is
approximately 58°C per package watt dissipated.
For example: If a 5D12.040SIP is delivering 0.9 watts at 5V
input, at what ambient could it expect to run with no additional
cooling such as moving air?
Efficiency is approximately 73% which leads to an input
power of 1.2 watts. The internal power loss is 1.2 - .9 = 0.30
watts. The case temperature rise will be 0.30W x 58°C/W=
17°C. This number is subtracted from the maximum case
temperature rating of 85°C to get 68°C, which is the maximum
ambient operating temperature.
This example calculation is for an application with no extra
air flow for cooling. Extra cooling air will greatly effect the
maximum ambient temperature. Exact internal power loss
depends upon the efficiency, input voltage, and load in the
application.
The above example is a rough approximation to the
maximum ambient temperature. Because of the difficulty of
defining ambient temperature, these calculations should be
verified by actual measurement before committing to a
production design.
0
10
2030
405060
7080
90
100
OUTPUT LOAD (%)
-6
-4
-2
0
2
4
6
8
10
NORMALIZED
OUTPUT
(%)
LOAD REGULATION
4.50
4.75
5.00
5.25
5.50
Input Voltage (VDC)
-15
-10
-5
0
5
10
15
Normalized
Output
(%)
Line Regulation
Typical Performance: (Tc=25°C)
Figure 4.
Unipolar output voltages up to 34 volts may be generated by
operating the SIP Dual Series converters in a single ended mode.
The CMN pin should not be directly used in your application.
Grounding
The input and output sections are fully floating and isolated
from each other. They may be operated fully floating or with
a common connection between the input and output.
Temperature Derating
The 1 Watt Output SIP series can be operated up to a +85°C
case temperature. Case temperature can be roughly calculated