Rev Date: 10/22/2020

4

www.seielect.com

This specification may be changed at any time without prior notice.

marketing@seielect.com

Please confirm technical specifications before you order and/or use.

HDM Series

Moisture Resistant Carbon Film Resistor

Stackpole Electronics, Inc.

Resistive Product Solutions

Repetitive Pulse Information:

If repetitive pulses are applied to resistors, pulse wave form must be less than “pulse limiting voltage”, “pulse limiting

current” or “pulse limiting wattage” calculated by the formula below.

Where: Vp:

Pulse limiting voltage (V)

lp:

Pulse limiting current (A)

Pp:

Pulse limiting wattage (W)

P:

Power rating (W)

R:

Nominal resistance (ohm)

T:

Repetitive period (sec)

t:

Pulse duration (sec)

K:

Coefficient: 0.8

[Vr:

Rated Voltage (V), Ir: Rated Current (A)]

Note 1:

If

T > 10 → T = 10 (sec), T / t > 1000 → T / t = 1000

Note 2:

If T > 10 and T / t > 1000, “Pulse Limiting power (Single pulse) is applied

Note 3:

If Vp < Vr (lp < lr or Pp < P), Vr (lr, P) is Vp (lp, Pp)

Note 4:

Pulse limiting voltage (current, wattage) is applied at less than rated ambient temperature.

If ambient temperature is more than the rated temperature (70 °C), decrease power rating according to

“Power Derating Curve”

Note 5:

Assure sufficient margin for

use period and conditions for “pulse limiting voltage”

Note 6:

If the pulse waveform is not square wave, judge after transform the waveform into square

wave according to the “Waveform Transformation to Square Wave”.

Vp =

K√P x R x T/t

lp =

K√P/P x T/t

Pp = K

2 x P x T/t