7.2.1 Design Requirements

The goal of this design example is to simplify the FVMC and FCMV functions of a PMU design using a SPDT

switch. The FVMC configuration is useful to test a device being used as a power supply, or in continuity or

leakage testing. In this configuration, the input voltage is directly applied to the DUT pin, and the current into or

out of the DUT pin is converted to a voltage by a sense resistor and measured by an analog to digital converter

(ADC). In the FCMV mode, an input current is forced to the DUT and the produced voltage on the DUT pin is

directly measured. In this example, the PMU design is required to meet the following specifications:

• Force voltage range: –15volts to +15volts

• Force current range: ±5µA to ±50mA

• Measure voltage range: –15volts to +15volts

• Measure current range: ±5µA to ±50mA

In addition to the voltage and current requirements, fast throughput is also a key requirement in ATE because it

relates directly to the cost of manufacturing the DUT.

7.2.2 Detailed Design Procedure

DAC

+

±

+

±

ADC

+

±

Force

Amplifier

RSENSE

TMUX6136

DUT

B

B

A

A

Current

Sense

Amplifier

Voltage

Sense

Amplifier

Av

Figure 7-3. FVMC Implementation in PMU Using

the TMUX6136

DAC

+

±

+

±

ADC

+

±

Force

Amplifier

RSENSE

TMUX6136

DUT

B

B

A

A

Current

Sense

Amplifier

Voltage

Sense

Amplifier

Av

Figure 7-4. FCMV Implementation in PMU Using

the TMUX6136

The implementation of the FVMC and FCMV modes can be combined with the use of a dual SPDT switch such

as the TMUX6136. Figure 7-3 and Figure 7-4 shows simplified diagrams of such implementations. In the FVMC

mode, the switch is toggled to position A and this allows the voltage sense amplifier to become part of the

feedback loop and the voltage output of the current sense amplifier to be sampled by the ADC. In the FCMV

mode, the switch is toggled to position B, and this allows the current sense amplifier to become part of the

feedback loop and the voltage output of the voltage sense amplifier to be sampled by the ADC.

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TMUX6136

SCDS397B – NOVEMBER 2018 – REVISED AUGUST 2025

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