Engee documentation

D Latch

The behavioral model of the D-latch.

blockType: AcausalElectricPowerSystems.IntegratedCircuits.Logic.DataLatch

d latch

Path in the library:

/Physical Modeling/Electrical/Integrated Circuits/Logic/D Latch

Description

Block D Latch implements the behavioral model of the D-latch. The block stores a single-bit value: 0 (low) or 1 (high).

The unit has two input ports that control the latch: data port D and resolution port E. When the logic level on port E is equal to 1, the block transmits data to the output port Q. When the logic level on port E is equal to 0, the block holds the output value in the previous state. The truth table below shows the logic levels at the inputs and outputs of the block. Lower index n indicates the value at the current time step, and n−1 — the value in the previous time step. Logic level on the inverted output port !Q is the reverse of the logical layer on port Q.

En Dn Qn

0

0

Qn-1

0

1

Qn-1

1

0

0

1

1

1

To set the logic level on port Q at the beginning of the simulation, in the parameter group Initial Targets set for the parameter Output logic meaning 0 or 1. The block uses this value as the initial logical level on port Q only if the initial logical level on port E is 0. In this case, the block usually stores the output value in the previous state. For more information about the initial values, see the article Configuring physical blocks using target values.

Gate inputs have infinite resistance and finite or zero capacitance.

If the gate voltage exceeds the threshold voltage, the block interprets the logic level at the input as 1. Otherwise, the block interprets the logic level at the input as 0. The unit calculates the threshold voltage as the average value of the parameters Low level input voltage and High level input voltage.

The output signal of the shutter depends on the parameter Output current-voltage relationship. Set this parameter to Linear to speed up the simulation, or Quadratic for more accurate results. For most models, it is recommended to use the value Linear. Meaning Quadratic It can be used to verify the results obtained using a simpler linear model.

If for the parameter Output current-voltage relationship the value is set Linear:

  • At the logical level 0 on the Q port, the output voltage is equal to the value of the parameter Low level output voltage.

  • At the logical level 1 on the Q port, the output voltage is equal to the value of the parameter High level output voltage.

  • The resistive-capacitive time constant of the gate output capacitor is equal to the value of the parameter Propagation delay.

If for the parameter Output current-voltage relationship the value is set Quadratic:

  • The output voltage is a function of the output current. For zero load current:

    • if the logic level on port Q is equal to 0, the output voltage is zero;

    • if the logic level on port Q is equal to 1, the output voltage is equal to the value of the parameter Supply voltage.

  • The delay of the shutter input signal approximately corresponds to the value of the parameter Propagation delay.

Assumptions and limitations

  • To increase the simulation speed, the unit does not simulate each internal MOSFET device of the gate individually. Therefore, the unit inaccurately models the gate response to input noise and input voltages close to the threshold voltage.

  • If you are modeling a feedback circuit around a set of logic gates, you must set the parameter Propagation delay a non-zero value for one or more gates.

Ports

Conserving

# D — data output
electricity

Details

A non-directional electrical port associated with data output.

Program usage name

data_pin

# Q — output contact
electricity

Details

A non-directional electrical port connected to the output pin.

Program usage name

output_pin

# E — resolution output
electricity

Details

A non-directional electrical port connected to the resolution pin.

Program usage name

enable_pin

# !Q — inverted output pin
electricity

Details

A non-directional electrical port connected to an inverted output pin.

Program usage name

inverted_output_pin

Parameters

Outputs

# Protection diode forward voltage — forward voltage of the protective diode
V | uV | mV | kV | MV

Details

The voltage that triggers the protective diode when exceeded.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

V | uV | mV | kV | MV
Default value

0.6 V
Program usage name

V_forward_diode
Evaluatable

Yes

# Propagation delay — time of change of the output voltage state
s | ns | us | ms | min | hr | d

Details

The time required to change the output voltage from the state low in the state of high or out of the state high in the state of low after changing the input logic levels.

If for the parameter Propagation delay the value is set 0, the value of the parameter Output resistance it should be positive.

Units

s | ns | us | ms | min | hr | d
Default value

25.0 ns
Program usage name

delay
Evaluatable

Yes

# Measurement voltage — Measuring supply voltage
V | uV | mV | kV | MV

Details

The gate supply voltage at which the output resistances and currents are set.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

V | uV | mV | kV | MV
Default value

5.0 V
Program usage name

V_measurement
Evaluatable

Yes

# Output resistance — output resistance
Ohm | mOhm | kOhm | MOhm | GOhm

Details

The output resistance that the unit uses to simulate the output voltage drop caused by the output current. This value can be calculated from the technical description by dividing the high-level output voltage by the maximum low-level output current.

If for the parameter Propagation delay the value is set 0, the value of the parameter Output resistance it should be positive.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Linear.

Units

Ohm | mOhm | kOhm | MOhm | GOhm
Default value

25.0 Ohm
Program usage name

R_output
Evaluatable

Yes

# Low level output voltage — output voltage at the logic level 0
V | uV | mV | kV | MV

Details

Output voltage when the logic level on the output port is equal to 0.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Linear.

Units

V | uV | mV | kV | MV
Default value

0.0 V
Program usage name

V_OL
Evaluatable

Yes

# High level output voltage — output voltage at the logic level 1
V | uV | mV | kV | MV

Details

Output voltage when the logic level on the output port is equal to 1.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Linear.

Units

V | uV | mV | kV | MV
Default value

5.0 V
Program usage name

V_OH
Evaluatable

Yes

# Logic HIGH output current I_OH when shorted to ground — output current at the logic level 1
A | pA | nA | uA | mA | kA | MA

Details

The output current is when the logic level at the output is 1 but the load causes the output voltage to tend to zero.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

A | pA | nA | uA | mA | kA | MA
Default value

63.0 mA
Program usage name

I_OH
Evaluatable

Yes

# Logic LOW output current I_OL when shorted to Vcc — output current at the logic level 0
A | pA | nA | uA | mA | kA | MA

Details

The output current is when the logic level at the output is 0, but the load causes the output voltage to tend to the value of the parameter Supply voltage.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

A | pA | nA | uA | mA | kA | MA
Default value

-45.0 mA
Program usage name

I_OL
Evaluatable

Yes

# Logic HIGH output resistance at zero current and at I_OH — resistance at the output logic level 1
Ohm | mOhm | kOhm | MOhm | GOhm

Details

Resistance when the logic level at the output is 1. Set the value for this parameter as a vector, a string of two resistance values. , where  — the gradient of the dependence of the output voltage on the current in the absence of an output current, and  — the gradient of the dependence of the output voltage on the current when the output is short-circuited to the ground.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

Ohm | mOhm | kOhm | MOhm | GOhm
Default value

[25.0, 250.0] Ohm
Program usage name

R_OH_vector
Evaluatable

Yes

# Output current-voltage relationship — the model of the dependence of the output current on the voltage
Linear | Quadratic

Details

A model that determines the dependence of the output current on the output voltage. Set this parameter to Linear for faster modeling and Quadratic for more accurate results.

Values

Linear | Quadratic
Default value

Linear
Program usage name

output_type
Evaluatable

No

# Logic LOW output resistance at zero current and at I_OL — resistance at the output logic level 0
Ohm | mOhm | kOhm | MOhm | GOhm

Details

Resistance when the logic level at the output is 0. Set the value for this parameter as a vector, a string of two resistance values. , where  — the gradient of the dependence of the output voltage on the current in the absence of an output current, and  — the gradient of the dependence of the output voltage on the current, when the load causes the output voltage to tend to the value of the parameter Supply voltage.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

Ohm | mOhm | kOhm | MOhm | GOhm
Default value

[30.0, 800.0] Ohm
Program usage name

R_OL_vector
Evaluatable

Yes

# Supply voltage — Supply voltage
V | uV | mV | kV | MV

Details

The voltage that is applied to the gate in the circuit.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

V | uV | mV | kV | MV
Default value

5 V
Program usage name

V_supply
Evaluatable

Yes

# Protection diode on resistance — resistance of an open protective diode
Ohm | mOhm | kOhm | MOhm | GOhm

Details

The voltage-current gradient for forward-biased protective diodes.

Dependencies

To use this parameter, set for the parameter Output current-voltage relationship meaning Quadratic.

Units

Ohm | mOhm | kOhm | MOhm | GOhm
Default value

5.0 Ohm
Program usage name

R_on_diode
Evaluatable

Yes

Inputs

# High level input voltage — the input voltage above which the logic level is 1
V | uV | mV | kV | MV

Details

The input voltage above which the block interprets the input logic level as 1.

Units

V | uV | mV | kV | MV
Default value

3.0 V
Program usage name

V_IH
Evaluatable

Yes

# Low level input voltage — the input voltage below which the logic level is 0
V | uV | mV | kV | MV

Details

The input voltage below which the block interprets the input logic level as 0.

Units

V | uV | mV | kV | MV
Default value

2.0 V
Program usage name

V_IL
Evaluatable

Yes

# Average input capacitance — input capacity of the MOSFET gate
F | pF | nF | uF | mF

Details

A fixed capacity approximately corresponding to the input capacity of the MOSFET gate. The MOSFET capacity depends on the applied voltage. If this unit is controlled by another shutter, the parameter Average input capacitance provides a rise time similar to the rise time of a MOSFET. The value of this capacity can be found in the manufacturer’s technical description. For a quick simulation, set this parameter to 0.

Units

F | pF | nF | uF | mF
Default value

5.0 pF
Program usage name

C_input
Evaluatable

Yes