NCE4953 vs the Other "4953" Parts: Full Comparison

Read the numbers by column and the trap is obvious. On the 10V figure the NCE4953 is at the back of the pack - 55mΩ against the VBsemi part's 35mΩ.

But switch to 4.5V gate drive and the picture inverts. The NCE4953's published 90mΩ beats both the Vishay and onsemi figures - and the VBsemi part has no 4.5V row at all.

So which column is better depends entirely on your gate rail. Here's the same family ranked at 10V drive and at 4.5V drive:

The part with the best 10V number is the one with no 4.5V number. That single fact is why substitution decisions in this family go wrong so often - people compare the column that is printed and ignore the column that is missing.

All figures above are as published by each manufacturer; resistor values, thermal ratings and revision levels differ between vendors and between revisions of the same vendor's sheet. Verify against the current revision of the specific vendor's own datasheet before you commit a BOM.

When to Use the Vishay or onsemi "4953"

If your board already carries an SI4953DY or an FDS4953 and the gate drive is a full 10V, either remains a legitimate replacement for the NCE4953 on paper - the resistance figures are within a few milliohms and the footprint is identical.

The catch is availability. FDS4953 is obsolete, so any design still calling for it is a redesign waiting to happen. The onsemi part's 175°C junction rating is the one genuine advantage it holds over the NCE4953, which is rated to 150°C.

When to Use the NCE4953

When your gate drive is 4.5V rather than 10V. The NCE4953 is the only part in this comparison with a published maximum at that voltage - 90mΩ - and it beats both the Vishay and onsemi figures. It also carries the best published thermal path at 50°C/W.

It is active, it comes on a 4000-piece reel rather than 2500, and its datasheet states both resistance conditions rather than only the flattering one. If you are replacing an obsolete FDS4953 and your gate rail is 5V logic, this is the straightforward answer.

When NOT to Use Any "4953" at All

None of these five publishes an avalanche energy rating, and none publishes a body-diode recovery time. If your load is a motor, a solenoid or a relay, the unclamped turn-off edge is an unquantified event on every part in this table.

And if you need steady current rather than a ten-second number, the SOP-8 package is the wrong shape regardless of vendor. All five qualify their thermal ratings at t ≤ 10 sec on FR4.

Above an amp or two continuous, a single TO-252 with a real heat path beats two SOP-8 dies every time.

Pinout & Layout Notes

Pin 1 is S1, pin 2 is G1, pin 3 is S2, pin 4 is G2; D1 sits on pins 7 and 8, D2 on pins 5 and 6. The two channels are independent - there is no internal drain tie - so both high-side switches are wired entirely on your board.

The pin-1 dot sits at the lower left, and it's a dot rather than a chamfer: the official package drawing marks it as a Ø0.6 identifier.

Don't carry a pin map across from the complementary NCE4606, which puts S2 and G2 on pins 1 and 2 with S1 and G1 on pins 3 and 4. Same footprint, swapped channels.

Two layout points the datasheet supports directly. The published thermal resistance is 50°C/W on an FR4 board at t ≤ 10 sec - a transient figure with no steady-state companion, so copper area is your only lever.

And both channels share one package-level thermal budget. Mounting them far apart on separate copper pours keeps one load's heat out of the other's path.

Other Alternatives Worth Knowing

Here's the thing that catches people out: the parts most often listed as "4953 equivalents" are frequently not duals at all. The SI4435DY appears in those lists because it shares the SO-8 footprint and the P-channel function, but it is a single channel with a very different current class.

What about the channel count your schematic actually needs? If it needs two, only a dual will do - and the pin map is what decides whether the swap is a drop-in or a re-spin.

The column that matters is the one that is missing. The VBsemi part leads the −10V ranking by 20mΩ and publishes nothing at −4.5V - so a designer who compares only the printed column will pick it and then run it at 5V drive, where it has no specification at all.

Frequently Asked Questions About NCE4953 Replacements

Q1: Is the FDS4953 a drop-in replacement for the NCE4953?

A: On the footprint yes, on the numbers only at 10V drive. Both are dual P-channel 30V SOP-8 with the same pin map, and 55mΩ at −10V is identical. At −4.5V the FDS4953 is quoted at 95mΩ against the NCE4953's 90mΩ. Note also that FDS4953 is obsolete, so it is a replacement you should be migrating away from.

Q2: Is a "4953" from another brand the same die?

A: No - the numbers prove it. Published −10V resistance across the family runs 35mΩ, 45mΩ, 53mΩ and 55mΩ. Three different figures that wide cannot come from one die. The shared part number fixes the package and the function, nothing more.

Q3: Which one should I choose if my gate drive is only 4.5V?

A: The NCE4953, from this comparison. It publishes 90mΩ max at −4.5V and 50°C/W, both better than the Vishay and onsemi figures at the same drive level. The VBsemi part publishes no −4.5V row at all, which makes it the worst choice for that rail despite its better 10V number.

Q4: Can I substitute the NCE4606 in a 4953 socket?

A: No. The NCE4606 is a complementary N+P pair, so one of its two channels is the wrong polarity for a dual-P position - and its channel numbers are swapped relative to the 4953 pin map. It is a different part for a different job, not a replacement.

Q5: What replaced the FDS4953?

A: Nothing official - which is why the question gets asked. The NCE4953 is a functional alternative with the same footprint, a slightly better −4.5V figure, and active supply. For designs that relied on the FDS4953's 175°C junction rating, check that substitution carefully: the NCE4953 is rated to 150°C.

Q6: Is the NCE4953-VB (VBsemi) a valid substitute?

A: Only at 10V gate drive, and only if you accept a different die. It publishes 35mΩ at −10V, a 7.3A current and a 5W dissipation figure - all better than the NCE original on paper. It also publishes no −4.5V row and carries a 1350pF input capacitance against the NCE4953's 520pF. Better numbers on one axis, no specification on another.

Q7: What is the pinout, and what is the layout trap?

A: Pin 1 is S1, pin 2 G1, pin 3 S2, pin 4 G2, with D1 on pins 7–8 and D2 on pins 5–6. The channels are independent. The trap is the complementary NCE4606, which shares the footprint but swaps the channel numbers - and both channels share a single package thermal budget, so separate copper pours keep them from heating each other.

Q8: What thermal numbers should I design against?

A: 2.5W and 50°C/W, both package-level and both ten-second ratings. The NCE4953 publishes one R_θJA row and one P_D row, qualified on FR4 at t ≤ 10 sec, with no steady-state figure. Both channels share that budget. At −5.1A and 4.5V drive a single channel already burns 2.34W - 94% of it.