135D データシートの表示（PDF） - Vishay Semiconductors

部品番号

コンポーネント説明

メーカー

135D

Wet Tantalum Capacitors Tantalum-Case with Glass-to-Tantalum Hermetic Seal for - 55 °C to + 200 °C Operation

Vishay Semiconductors 

www.vishay.com

GUIDE TO APPLICATION

1. AC Ripple Current: Subjecting a capacitor to an AC

voltage causes an AC current to flow through it. The

amplitude of the current is dependent on the impedance

of the capacitor at the frequency of the applied signal:

I

=

V---

Z

where:

I = Ripple current

V = Applied AC voltage

Z = Impedance of capacitor (frequency dependent)

This current causes heating in the capacitor because of

I2R losses (R is the equivalent series resistance at the

applied frequency). This heating or power dissipation, is

one of the limiting factors of the capacitor’s ripple current

rating.

CASE CODE

C

F

T

K

MAXIMUM PERMISSIBLE

POWER DISSIPATION

AT + 25 °C (W) IN FREE AIR

1.00

1.55

1.75

1.95

These power dissipation ratings are based on a

calculated + 50 °C internal temperature rise in still air. The

maximum allowable ripple currents given in the Standard

and Extended Ratings tables are based on these ratings

and the maximum equivalent series resistance at that

frequency.

The relationship is written as follows:

P = I2R

where:

P = Maximum power

I = Maximum ripple current

R = Equivalent series resistance

Therefore:

where:

R is in 

P is in W

I is in ARMS

I = -P--

R

2. AC Ripple Voltage: In operation, the peak voltage across

the capacitor (DC working voltage plus peak ripple

voltage) must not exceed the rated working voltage of the

capacitor. The DC component of the applied voltage

should be sufficiently large to prevent polarity reversal in

excess of 3 V at + 85 °C or 2 V at 125 °C.

135D

Vishay

There will be a point at the lower frequency and

capacitance values when the peak AC voltage will be the

limiting factor on the ripple current - not its heating

effects.

For example:

Given a 25 μF, 8 V capacitor in the “C” case code and

assuming a ripple current application at a frequency of

120 Hz, the total maximum allowable peak to peak

voltage at + 25 °C is:

8 VF + 3 VR = 11 Vpp

In order to allow the full swing of 11 Vpp and not exceed

rated forward or rated reverse, a DC bias of 2.5 V is

assumed to be applied.

From the ”Standard Ratings Table”, the maximum ripple

current at 40 kHz is 0.820 A. Compensating for the lower

frequency from the “Ripple Current Multipliers” tables:

IRMS (120 Hz) = 0.820 A x 0.6 = 0.492 ARMS

This current rating is calculated strictly on the basis of

maximum power dissipation. Now calculate what

impressed voltage this amount of current will cause

across this capacitor.

Assuming a sinusoidal voltage, calculate the rated peak

to peak current:

Ipp = IRMS x 2 2 = 0.492 x 2.828 = 1.39 App

Vppimpressed= Ipp x ZC 120 Hz

where:

2

Z C  120 H z 

=





ESR2 +

(XC(120



Hz)

ESR = 4  (from “Standard Ratings” table)

1

1

XC = 2fC = 212025 x 10-6 = 53.1 

Therefore:

ZC = 42 + 53.12 = 53.3 

and

Vppimpressed = 1.39 App x 53.3 

= 74.1 Vpp  11 Vpp

Therefore, the peak voltage of the capacitor is the limiting

factor for the ripple current and can be calculated as

follows:

Max. Ipp

=

V----C----p---p------a---l--l--o----w----e----d----

ZC

=

-1---1----.-0------V---

53.3 

=

0.206

App

or

0----.-2----0---6--

22

=

0.073

ARMS

at

120

Hz

Revision: 09-Apr-13

10

Document Number: 40024

For technical questions, contact: tantalum@vishay.com

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000

Share Link: