What Is the Reverse Leakage Current of an ASIM TVS Diode?

An ASIM TVS diode does not have one brand-wide reverse leakage current. Reverse leakage is written as IR and belongs to a specific part number under a stated reverse voltage and temperature. In the public SMA04J Rev1.4 table, the maximum IR is 800 μA for the 5 V grade, 200 μA for the 7 V grade, 5 μA for the 10 V grade, and 1 μA for the 24 V grade. These values are not a rule that leakage falls with voltage; they are conditioned limits for different devices in one family.

Direct answer: provide the complete part number before quoting leakage. A value without reverse test voltage, temperature, maximum-versus-typical status, and stress history is not suitable for standby-current, sensor-error, or incoming-inspection decisions.

Real examples from an ASIM TVS family

The following rows come from SMA04J Rev1.4. The electrical-characteristics table is specified at 25 °C, and IR is listed at each device's VRWM.

A separate public sheet, SODA6.0B-SH Rev1.2, lists 6.0 V VRWM and 400 μA maximum IR at VRWM under its 25 °C table condition. A similar voltage label therefore does not create a like-for-like leakage comparison across families.

How IR is defined

Reverse leakage current is the current that flows through the reverse-biased TVS before the device reaches its breakdown region. A data sheet commonly reports it as IR @ VRWM. Measuring at a lower voltage can produce a different result. Moving closer to breakdown, increasing temperature, contaminating the PCB surface, or stressing the junction can increase the measured current.

A usable leakage record includes all of these fields:

• complete part number and data-sheet revision;

• unidirectional or bidirectional construction;

• applied reverse voltage and polarity;

• ambient or device temperature and settling time;

• instrument range, resolution, and fixture background leakage;

• pre-stress or post-ESD/post-surge status;

• sample quantity and lot identity when the result supports production approval.

Removing any of these conditions turns a measured result into an ambiguous number.

Why temperature must accompany the value

Semiconductor junction leakage is temperature-sensitive. A maximum limit in a 25 °C characteristics table does not automatically define performance at 85 °C, 125 °C, or inside a sealed enclosure. A temperature-sensitive design should use the selected model's curves where available or characterize samples under controlled conditions.

A useful hot-leakage test fixes the board or device temperature, settling time, applied voltage, humidity, fixture, and instrument range. Blowing hot air toward a component and reading a changing meter does not separate device temperature from board-surface leakage and measurement drift.

When a vendor curve is unavailable, the report should say that the result is a project measurement for the tested samples and conditions. It should not be presented as a replacement for a guaranteed production limit.

Where leakage matters in a real product

On a power input, several hundred microamperes may primarily affect standby consumption. On a high-impedance sensor, bias network, wake-up pin, or precision measurement node, the same current can shift the operating point substantially.

A first-order check is:

node error = leakage current × equivalent source resistance

This calculation is only a screening estimate. The actual node also contains input bias current, PCB surface resistance, parallel protection branches, connector contamination, voltage-dependent TVS behavior, and temperature effects. High-impedance designs should include an explicit maximum IR criterion rather than relying only on ESD level or junction capacitance.

Why board standby current is not the TVS leakage current

Current measured at a product input includes regulator quiescent current, resistor dividers, capacitors, indicators, connector contamination, and instrument error. A board measurement cannot be assigned to the TVS without separation.

Use a controlled A/B/A sequence:

1. Measure the populated board at a fixed voltage, temperature, and settling time.

2. Remove the TVS or use a matched unpopulated comparison board and repeat the measurement.

3. Restore a device from the same lot and verify that the difference returns.

4. Measure devices from that lot in a dedicated low-leakage fixture.

5. Repeat the same measurements after the specified ESD or surge stress.

If the difference is not repeatable, inspect board cleanliness, humidity, fixtures, probes, and parallel branches before declaring a component defect.

How to compare two TVS leakage specifications

A comparison table should align the measurement conditions before it aligns the numerical values.

After normalizing these fields, the device still has to pass VRWM, VBR, VC, IPP, capacitance, package, and PCB-path requirements. Low leakage alone does not make a TVS suitable.

Why post-stress leakage belongs in the validation plan

A TVS can remain functionally conductive yet show a leakage shift after repeated transients. Pre- and post-stress measurements should use the same voltage, temperature, settling time, fixture, and range. Samples need stable identifiers so that changes are measured on the same devices rather than averaged across unrelated parts.

If leakage rises together with standby current, local heating, or signal bias error, further stressing should stop until the TVS and the protected circuit are inspected. A system that still powers on has not necessarily retained the original component margin.

How ASIM data sheets support traceability

ASIM family sheets place IR in the same row as VRWM, VBR, VC, and IPP. This matters because leakage cannot be evaluated independently of the normal voltage and transient window. SMA04J Rev1.4 and SODA6.0B-SH Rev1.2 also demonstrate why a family or brand summary is insufficient: different designs can carry very different IR limits.

For procurement approval, retain the data-sheet revision, sample lot, device marking, and measurement record. For leakage-sensitive applications, define a controlled voltage-and-temperature sample test. Do not convert a catalog maximum into a claim that every shipped unit will measure exactly that value.

A leakage review checklist

Before signing off a part number, confirm that:

1. the complete part number and polarity are known;

2. IR is copied from the matching revision and row;

3. the reverse voltage and temperature condition are recorded;

4. maximum and typical values are not mixed;

5. board background leakage has been characterized;

6. the source impedance and allowed node error are known;

7. leakage is rechecked after the required transient stress;

8. any lot-acceptance limit is supported by a documented test method.

Frequently asked questions

Do all 24 V TVS diodes have 1 μA leakage?

No. SMA04J24V Rev1.4 lists a 1 μA maximum under its table condition. Another 24 V part, package, or family may specify a different limit. Read the exact data sheet.

Does lower IR prove stronger transient protection?

No. IR describes the off-state current. Transient protection also depends on VC, IPP, waveform, dynamic behavior, package, and the PCB current path.

Can a handheld multimeter verify a 1 μA limit?

Only if the source voltage, range, fixture leakage, resolution, settling time, and environmental conditions are suitable. A dedicated source-measure setup is often more controllable for microampere-level work.

Sources

• ASIM SMA04J Series Data Sheet, Rev1.4

• ASIM SODA6.0B-SH Data Sheet, Rev1.2

• ASIM ESD24R300TA Data Sheet, Rev1.2

• Nexperia TVS Diode Selection White Paper

Sources checked on September 24, 2026. Use the current revision archived for the approved part number.