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5
Type 255D
Vishay Sprague
Document Number: 40052
Revision 04-Feb-03
PERFORMANCE CHARACTERISTICS
(Continued)
1.
A-C Ripple Current:
The maximum allowable ripple
current shall be determined from the formula:
where,
P = Power Dissipation in Watts @ + 25
°
C as given in
the table in Paragraph Number 5 (Power
Dissipation).
R
ESR
=The capacitor Equivalent Series Resistance at the
specified frequency.
2.
A-C Ripple Voltage:
The maximum allowable ripple
voltage shall be determined from the formula:
or, from the formula:
where,
P = Power Dissipation in Watts @ + 25
°
C as given in
the table in Paragraph Number 5 (Power
Dissipation).
R
ESR
=The capacitor Equivalent Series Resistance at the
specified frequency.
Z = The capacitor impedance at the specified frequency.
2.1
The sum of the peak AC voltage plus the DC voltage
shall not exceed the DC voltage rating of the capacitor.
V
rms
= I
rms
x Z
2.4
Power Dissipation
: Power dissipation will be affected
by the heat sinking capability of the mounting surface.
Non-sinusoidal ripple current may produce heating
effects which differ from those shown. It is important
that the equivalent
Irms
value be established when
calculating permissible operating levels. (Power
Dissipation calculated using +25
°
C temperature rise).
I
rms
=
P
R
ESR
V
rms
=
P
R
ESR
CASE CODE
MAXIMUM PERMISSIBLE
POWER DISSIPATION
@ + 25C (Watts) IN FREE AIR
D
0.150
TEMPERATURE
DERATING FACTOR
+25
°
C
+ 85
°
C
+ 105
°
C
1.0
0.9
0.4
10.
Solderability:
Capacitors will meet the solderability
requirements of (MIL-STD-202, method 208),
ANSI/J-STD-002, Test B.
11.
Resistance to Solder Heat:
Capacitors will with stand
reflow soldering @ + 240
°
C + 5
°
C for 10 seconds max.
Capacitors should be allowed to remain at ambient
conditions for a period of up to 24 hours prior to
electrical measurements.
11.1
Following the resistance to solder heat test,
capacitance, be within
±
20% of the initial value, the
dissipation factor and the DC leakage current shall not
exceed the initial value.
12.
Terminal Strength:
Per IEC-384-3, minimum of 3N
shear force.
13.
Flammability:
Encapsulant materials meet UL94 VO
with an oxygen index of 32%.
GUIDE TO APPLICATION
14.
Capacitor Failure Mode:
The predominant failure
mode for solid tantalum capacitors is increased leak-
age current resulting in a shorted circuit. Capacitor
failure may result from excess forward or reverse DC
voltage, surge current, ripple current, thermal shock
or excessive temperature. The increase in leakage is
caused by a breakdown of the Ta2O5 dielecric. For
additional information on leakage failure of solid tan-
talum chip capacitors, refer to Vishay Sprague Tech-
nical Paper, “Leakage Failure Mode in Solid Tantalum
Chip Capacitors.”
15 Humidity Test:
Capacitors shall withstand 500 hours at
+ 60
°
C, 90% to 95% relative humidity, with no voltage
applied.
15.1
Following the humidity test, capacitance change shall
not exceed -20% to + 40% of the initial value, dissipation
factor shall not exceed 150% of the initial requirement;
leakage current shall not exceed 0.1CV (9uA).
2.2
The sum of the negative peak AC voltage plus the
applied DC voltage shall not allow a voltage reversal
exceeding 10% of the DC working voltage at + 25
°
C.
Temperature Derating
: If these capacitors are to be
operated at temperatures above + 25
°
C, the
permissible rms ripple current or voltage shall be
calculated using the derating factors as shown:
2.3
3.
Reverse Voltage:
These capacitors are capable of
withstanding peak voltages in the reverse direction
equal to 10% of the DC rating at + 25
°
C, 5% of the DC
rating at + 85
°
C and 1% of the DC rating at +105
°
C.