ADGM3121BCCZ-R2 datasheet(28/33 Pages) AD

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Data Sheet

ADGM3121

CRITICAL OPERATIONAL REQUIREMENTS

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Rev. 0 | 28 of 33

SYSTEM ERROR CONSIDERATIONS DUE TO

ON‑RESISTANCE DRIFT

The on-resistance (RON) performance of the ADGM3121 is affected

by part-to-part variation, channel-to-channel variation, cycle actua-

tions, settling time post turn on, bias voltage, and temperature

changes.

In a 50Ω system, the on-resistance drift over switch actuations

(∆RON) can introduce system inaccuracy. Figure 75 shows the

ADGM3121 connected with the load in a 50Ω system, where RS is

the source impedance. To calculate the system error caused by the

ADGM3121 ∆RON, use the following equation:

System Error (%) = ΔR / RLOAD

where:

ΔR is the ADGM3121 ∆RON.

RLOAD is the load impedance.

The ADGM3121 ∆RON also affects insertion loss, which must be

considered when using the device. To calculate the on-resistance

impact on insertion loss, use the following equation:

Insertion Loss = 10log (1 + (ΔR / RLOAD))

Figure 75. 50Ω System Representation Where the ADGM3121 Is Connected

with the Load

Table 9. System Error and Insertion Loss Error Due to ADGM3121 RON Drift

On-Resistance Drift

System Error

(%)

Insertion Loss Error (dB)

0.7

1.4

0.06

0.17

The ∆RON over time specification is −0.32Ω (maximum) measured

after 100ms, as shown in Figure 13 to Figure 20. According to the

plots, the RON drifts over time is −0.06Ω (typical) after 100ms. The

RON of the ADGM3121 typically drifts by −0.04Ω per decade. For

example, after 100ms, the RON drifts −0.06Ω. After 1s, the RON

drifts −0.1Ω. And after 10s, it drifts −0.14Ω. Therefore, after 1000s,

the RON is expected to drift by −0.22Ω.

ON-RESISTANCE SHIFT DUE TO

TEMPERATURE SHOCK POST ACTUATIONS

When the switch is actuated multiple times at one temperature, if

there is a sudden shift from this temperature, a large shift is shown

in the switch RON. Figure 76 shows the absolute RON performance

of the population of devices over different number of actuations.

During this measurement, the switch is actuated at 85°C and the

switch RON is measured at 25°C. Actuating the switch at 85°C

and measuring RON at 25°C is the most severe condition for the

ADGM3121 ∆RON over actuations.

Figure 76. Population vs. Absolute RON, Switch Actuated at 85°C and RON

Measured at 25°C, Actuation Frequency = 289Hz, VDD = 3.3V

HOT SWITCHING

Hot switching occurs by cycling the switch on or off with an exces-

sive voltage or current applied to the switch. The presence of

the applied signal during the switching cycle damages the switch

contacts. Hot switching damage is dependent on the current or the

voltage levels. Hot switching causes a significant reduction in the

cycle lifetime of the switch, as shown in Figure 80 and Figure 82.

Figure 77 shows the hot switching condition when the switch is

turned on with 1V present at the switch terminal during switching.

With a voltage across an off switch, damage can occur as the

contact or switch closes.

Figure 77. Hot Switching Condition When Turning the Switch from Off to On

Figure 78 shows the hot switching condition when the switch is

turned off with 10mA passing through the switch during switching.

With current passing through an on switch, damage can occur as

the contact or switch opens.

Figure 78. Hot Switching Condition When Turning the Switch from On to Off

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