Trying to get a MAX44280 model to run in QTSPICE

Hello everyone,
I’m trying to get the attached model of a MAX44280 OpAmp to run in QSpice. The model is the result
of importing the Spice model provided at MAX44280 Datasheet and Product Info | Analog Devices

When trying to run a transient simulation I get the following warning:
This circuit has one floating node. From inspection, this node is believed to be floating: 98•X1
Warning: Singular matrix. Check node 98•X1
Which then results in a: Fatal error: Timestep too small(1.25e-19) at t=0

Attempted Solution
I’ve checked the model and found the following devices to be connected to Node 98:

GD24A 98 98A TABLE { V(98,98A) } ((-3m,-1000)(-2m,-10)(-1m,-1)(0,0)(1,1n))
GD24B 98 98B TABLE { V(98,98B) } ((-1,-1n)(0,0)(1m,1)(2m,10)(3m,1000))
R24A 0 98A 1 TC=0.00,0.00
R24B 0 98B 1 TC=0.00,0.00
G70 0 98 TABLE { V(96,5X) } ((-11.0,-85.6M)(-1.00M,-84.7M)(0,0)(1.00M,84.7M)(11.0,85.6M))

I’ve added the line:
R99 0 98 10G TC=0.00,0.00
to negate the floating node issue: but now the simulation fails with a: Fatal error: Timestep too small(1.25e-19) at t=0

I’ve added
.options gmin=1e-10
.options abstol=1e-10
.options reltol=0.003
.options cshunt=1e-15
But I’m still getting a: Fatal error: Timestep too small(1.73192e-19) at t=3.85533e-07


  1. What kind of device is GD24A? Per the QSpice help “Gnn” describes a Voltage dependet current source. But I’m not sure, whether D24A is a valid value for nn, which I had assumed to mean a two digit integer, as in the forth line above: G70
  2. What does the expresion in curly brackets after TABLE mean? The syntax for TABLE, according to the “Expression of Waveform Data” help page only allows for parantheses
  3. Is the TC expression used in the two resistors equivalent to a TCE or TC1?
  4. Is 98A a valid value for a node?
  5. How can I get the model to simulate?

I’d be thankful for you help,
kind regards,

max44280.qsym (6.0 KB)

Any chance you mix up Negative Supply and Output pin position?


Hey Kelvin, thank you for taking a look!
The pins are indded wrong. I’ve fixed the model but the problem persists.

max44280.qsym (6.0 KB)

I try to run this model in Qspice or LTspice, and both return timestep too small warning. Let see if other expert in this forum can help. But what interesting is that, even LTspice not include MAX44280 in its op-amp library.