I am trying to use the TLV2241 DIP package IC to make a relaxation
oscillator(square wave oscillator using positive feedback). I first
simulated the design in spice (both ORCAD PSPICE and WINSPICE). I used
the SPICE model of the TLV2241 provided in the data sheet provided by
TI.COM . Please see the spice circuit file below.
Problem: In the simulated version I get an oscillation period of approx
6.2ms. However when I built the circuit using the chip I actually got a
frequency of 19Hz(Period approx 52ms)
I have made sure that all components are close to the specs as
specified in the spice simulation
Question) Is the model provided by TI, as shown below, adequate to
accurately model the opamp. Please suggest why is there such a
disparity between spice simulation(s) and the actual circuit?
Thanks
SPICE CIRCUIT FILE FOR SQUARE WAVE GENERATOR USING TLV2241
----------------------------------------------------------
*Relaxation oscillator using a single supply opamp
* connections: non-inverting input
* | inverting input
* | | positive power supply
* | | | negative power supply
* | | | | output
* | | | | |
..SUBCKT TLV2241 1 2 3 4 5
C1 11 12 9.8944E-12
C2 6 7 30.000E-12
CEE 10 99 8.8738E-12
DC 5 53 DY
DE 54 5 DY
DLP 90 91 DX
DLN 92 90 DX
DP 4 3 DX
EGND 99 0 POLY(2) (3,0) (4,0) 0 .5 .5
FB 7 99 POLY(5) VB VC VE VLP VLN 0 61.404E6 -1E3 1E3 61E6 -61E6
GA 6 0 11 12 1.0216E-6
GCM 0 6 10 99 10.216E-12
IEE 10 4 DC 54.540E-9
IOFF 0 6 DC 5E-12
HLIM 90 0 VLIM 1K
Q1 11 2 13 QX1
Q2 12 1 14 QX2
R2 6 9 100.00E3
RC1 3 11 978.81E3
RC2 3 12 978.81E3
RE1 13 10 30.364E3
RE2 14 10 30.364E3
REE 10 99 3.6670E9
RO1 8 5 10
RO2 7 99 10
RP 3 4 1.4183E6
VB 9 0 DC 0
VC 3 53 DC .88315
VE 54 4 DC .88315
VLIM 7 8 DC 0
VLP 91 0 DC 540
VLN 0 92 DC 540
..MODEL DX D(IS=800.00E-18)
..MODEL DY D(IS=800.00E-18 RS=1M CJO=10P)
..MODEL QX1 NPN(IS=800.00E-18 BF=27.270E21)
..MODEL QX2 NPN(IS=800.0000E-18 BF=27.270E21)
..ENDS
XOP1 3 1 4 0 2 TLV2241
Cout 2 6 0.033uF
RF 1 6 9.99K
CF 1 0 10uF
R2 6 3 1.001K
R1 3 0 19.97K
VS1 4 0 5V
..TRAN 0.01ms 100ms
..PROBE
..PLOT TRAN V(2)
..END
oscillator(square wave oscillator using positive feedback). I first
simulated the design in spice (both ORCAD PSPICE and WINSPICE). I used
the SPICE model of the TLV2241 provided in the data sheet provided by
TI.COM . Please see the spice circuit file below.
Problem: In the simulated version I get an oscillation period of approx
6.2ms. However when I built the circuit using the chip I actually got a
frequency of 19Hz(Period approx 52ms)
I have made sure that all components are close to the specs as
specified in the spice simulation
Question) Is the model provided by TI, as shown below, adequate to
accurately model the opamp. Please suggest why is there such a
disparity between spice simulation(s) and the actual circuit?
Thanks
SPICE CIRCUIT FILE FOR SQUARE WAVE GENERATOR USING TLV2241
----------------------------------------------------------
*Relaxation oscillator using a single supply opamp
* connections: non-inverting input
* | inverting input
* | | positive power supply
* | | | negative power supply
* | | | | output
* | | | | |
..SUBCKT TLV2241 1 2 3 4 5
C1 11 12 9.8944E-12
C2 6 7 30.000E-12
CEE 10 99 8.8738E-12
DC 5 53 DY
DE 54 5 DY
DLP 90 91 DX
DLN 92 90 DX
DP 4 3 DX
EGND 99 0 POLY(2) (3,0) (4,0) 0 .5 .5
FB 7 99 POLY(5) VB VC VE VLP VLN 0 61.404E6 -1E3 1E3 61E6 -61E6
GA 6 0 11 12 1.0216E-6
GCM 0 6 10 99 10.216E-12
IEE 10 4 DC 54.540E-9
IOFF 0 6 DC 5E-12
HLIM 90 0 VLIM 1K
Q1 11 2 13 QX1
Q2 12 1 14 QX2
R2 6 9 100.00E3
RC1 3 11 978.81E3
RC2 3 12 978.81E3
RE1 13 10 30.364E3
RE2 14 10 30.364E3
REE 10 99 3.6670E9
RO1 8 5 10
RO2 7 99 10
RP 3 4 1.4183E6
VB 9 0 DC 0
VC 3 53 DC .88315
VE 54 4 DC .88315
VLIM 7 8 DC 0
VLP 91 0 DC 540
VLN 0 92 DC 540
..MODEL DX D(IS=800.00E-18)
..MODEL DY D(IS=800.00E-18 RS=1M CJO=10P)
..MODEL QX1 NPN(IS=800.00E-18 BF=27.270E21)
..MODEL QX2 NPN(IS=800.0000E-18 BF=27.270E21)
..ENDS
XOP1 3 1 4 0 2 TLV2241
Cout 2 6 0.033uF
RF 1 6 9.99K
CF 1 0 10uF
R2 6 3 1.001K
R1 3 0 19.97K
VS1 4 0 5V
..TRAN 0.01ms 100ms
..PROBE
..PLOT TRAN V(2)
..END
