FF with High True Enables...

R

Ricketty C

Guest
The only FF devices I can find with a high true reset control are the CD4013 and CD4027 and the part number variations of those parts. Is this it? Do none of the AC, AHC, HC, VLC,... use high true resets?

I thought there were parts made in the HC or AHC technology with the 40xx numbers and functions, but I\'m not finding them at digikey.

The circuit I\'m using it in is a hybrid analog/digital thing. I want to detect a voltage (representing a motor current) has risen above a threshold for some amount of time, then set a FF that controls power to a motor, disabling the motor.

I went through an iteration of this circuit using MOSFETs (1 N-channel and 1 higher power P-channel) to form the FF and two more to provide control from lower voltage inputs. The input that turns the motor off is from a comparator that detects transitions above the threshold. The output is OC with a pullup and a cap to act as a timer. Reaching the threshold of the input control FET flips the flop turning off the motor. The other input is from the MCU to turn it back on. Another FETs is used to detect the state of the FF to match the MCU input voltage.

Using a proper FF allows three of the transistors to be removed and a few passives. The level of the RC output from the comparator is used to control the reset input to the FF. The MCU input is direct to the clock input which with the D held high sets the FF. The FF output then drives the FETs that control the motor. Simple. But...

I\'m concerned that this is using the input threshold to set the level of the RC on the output of the comparator. It looks like it can cause a range of 50 to 200 ms to detect the high current condition. I was hoping to find a different flavor of device with a better specified input spec, but this requires a high true rest and there only seems to be two PNs that have this, CD4013 and CD4027.

I\'m pretty sure the variation in timing is not at all important. This is to detect the motor running to the stops if the software craps out. Turning off in 50 ms won\'t be so different from 200 ms I expect. It\'s not like we have any hard spec. This project is running pretty open loop in that regard.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
I pushed the transistor version around until I found a couple more optimizations and I think that is the better circuit now. No new parts added to the BoM other than the P-MOSFET needed to handle the motor current.

I optimized it by not using the PFET as part of the FF since that made the FF all 15 volt logic which was hard to interface to the low voltage circuit.. I could use two NFETs to make the FF on the low voltage rail, but the final optimization was to eliminate the NFET interfacing the timing RC by putting the OC comparator output in series with one of the NFETs. That created an OR gate to allow the transistor to accept two inputs.

I added two resistors in the load of the other NFET so there was a node the MCU can pull up or down through a cap to turn the motor back on or to turn it off although that should not be needed as there is a motor controller to handle that. This circuit is kill the motor power if it goes to the stops too long.

I\'m pretty happy with the result and no logic chip required.

Here is the LTspice circuit if anyone cares to see it.

Version 4
SHEET 1 1752 708
WIRE -688 -256 -704 -256
WIRE -704 -240 -704 -256
WIRE 416 -192 400 -192
WIRE 416 -176 416 -192
WIRE 656 -112 640 -112
WIRE -688 -96 -704 -96
WIRE -496 -96 -512 -96
WIRE 656 -96 656 -112
WIRE -704 -80 -704 -96
WIRE -496 -80 -496 -96
WIRE 256 -64 240 -64
WIRE 304 -64 256 -64
WIRE 416 -64 416 -96
WIRE 416 -64 368 -64
WIRE 480 -64 416 -64
WIRE 560 -64 480 -64
WIRE 832 -48 816 -48
WIRE 416 -32 416 -64
WIRE -288 0 -320 0
WIRE -48 0 -288 0
WIRE 832 0 832 -48
WIRE 656 16 656 -16
WIRE 656 16 512 16
WIRE 736 16 656 16
WIRE 784 16 736 16
WIRE -320 32 -320 0
WIRE -496 48 -496 0
WIRE -432 48 -496 48
WIRE -368 48 -432 48
WIRE 656 48 656 16
WIRE -688 64 -704 64
WIRE -704 80 -704 64
WIRE 352 80 320 80
WIRE 416 80 416 48
WIRE 416 80 352 80
WIRE -496 96 -496 48
WIRE -368 96 -400 96
WIRE -400 112 -400 96
WIRE 416 112 416 80
WIRE -320 128 -320 112
WIRE 560 128 560 -64
WIRE 608 128 560 128
WIRE 832 144 832 96
WIRE 912 144 832 144
WIRE 960 144 912 144
WIRE -144 176 -160 176
WIRE 832 176 832 144
WIRE 960 176 960 144
WIRE -496 192 -496 176
WIRE -496 192 -512 192
WIRE -144 192 -144 176
WIRE 512 192 512 16
WIRE 512 192 464 192
WIRE -688 224 -704 224
WIRE 416 224 416 208
WIRE -704 240 -704 224
WIRE 96 256 80 256
WIRE 768 272 752 272
WIRE 832 272 832 256
WIRE 832 272 768 272
WIRE 96 288 96 256
WIRE 832 288 832 272
WIRE 960 288 960 256
WIRE -144 304 -144 272
WIRE 16 304 -144 304
WIRE 64 304 16 304
WIRE 208 320 128 320
WIRE 272 320 208 320
WIRE 400 320 352 320
WIRE 464 320 400 320
WIRE 656 320 656 144
WIRE 656 320 464 320
WIRE -144 336 -144 304
WIRE -48 336 -48 0
WIRE 16 336 -48 336
WIRE 64 336 16 336
WIRE 400 352 400 320
WIRE -560 368 -576 368
WIRE -48 368 -48 336
WIRE 96 368 96 352
WIRE -576 384 -576 368
WIRE 832 384 832 352
WIRE -688 432 -704 432
WIRE -144 432 -144 416
WIRE 400 432 400 416
WIRE -704 448 -704 432
WIRE -48 480 -48 448
FLAG 96 368 0
FLAG -48 480 0
FLAG -704 432 SIG
FLAG -704 224 NOISE
FLAG -704 528 0
FLAG -704 320 0
FLAG -496 -96 SIG
FLAG -496 192 NOISE
FLAG -288 0 Input
FLAG 16 336 U1+
FLAG 208 320 SIXAMPS
FLAG -320 128 0
FLAG -400 112 0
FLAG -144 432 0
FLAG 16 304 VREF
FLAG -144 176 3V3
FLAG 400 432 0
FLAG -432 48 SUM
FLAG -704 160 0
FLAG -704 64 3V3
FLAG -704 0 0
FLAG -704 -96 5V
FLAG 656 -112 VIN
FLAG 736 16 OFF
FLAG 832 -48 VIN
FLAG -576 464 0
FLAG -576 368 VIN
FLAG 352 80 ON
FLAG 416 224 0
FLAG 96 256 3V3
FLAG -704 -160 0
FLAG -704 -256 MOT_ON
FLAG 416 -192 3V3
FLAG 256 -64 MOT_ON
FLAG 464 320 OVR
FLAG 480 -64 FORCE
FLAG 960 288 0
FLAG 912 144 VMOT
FLAG 832 384 0
FLAG 768 272 DIODE
SYMBOL voltage -704 64 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V1
SYMATTR Value 3.3
SYMBOL res -64 352 R0
SYMATTR InstName R3
SYMATTR Value 1.5K
SYMBOL voltage -704 432 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 24 96 Left 1
SYMATTR Value PWL(0 0 0.5 0 0.51 4 1 4 1.005 8 1.05 8 1.055 4 1.1 4 1.105 8 1.15 8 1.155 4 1.2 4 1.205 8 1.25 8 1.255 4 1.3 4 1.305 8 1.35 8 1.355 4 1..4 4 1.405 8 1.45 8 1.455 4 1.5 4 1.505 8 1.55 8 1.555 4 1.6 4 1.605 8 2 8 2.005 4 2.6 4 2.605 8)
SYMATTR InstName V2
SYMBOL bv -704 224 R0
SYMATTR InstName B1
SYMATTR Value V=0.2*(white(2e1*time))
SYMBOL res -512 -96 R0
SYMATTR InstName R10
SYMATTR Value 1k
SYMBOL res -512 80 R0
SYMATTR InstName R11
SYMATTR Value 100k
SYMBOL res -160 176 R0
SYMATTR InstName R1
SYMATTR Value 1Meg
SYMBOL g -320 16 R0
WINDOW 3 16 98 Left 2
SYMATTR Value 142.25E-6
SYMATTR InstName G1
SYMBOL cap 384 352 R0
SYMATTR InstName C1
SYMATTR Value 22µF
SYMBOL Comparators\\\\LTC1841 96 320 R0
WINDOW 3 25 58 Left 2
SYMATTR InstName U1
SYMBOL res 368 304 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 1k
SYMBOL res -160 320 R0
SYMATTR InstName R2
SYMATTR Value 620k
SYMBOL voltage -704 -96 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL res 640 -112 R0
SYMATTR InstName R8
SYMATTR Value 46k4
SYMBOL pmos 784 96 M180
SYMATTR InstName M3
SYMATTR Value AOD4185
SYMBOL voltage -576 368 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V4
SYMATTR Value PULSE(0 14.7 0.01 0.02 0.12 15)
SYMBOL nmos 464 112 M0
SYMATTR InstName M1
SYMATTR Value 2N7002
SYMBOL voltage -704 -256 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V5
SYMATTR Value PULSE(3.3 00 0.1 10us 10us 0.01 2.4)
SYMBOL res 400 -192 R0
SYMATTR InstName R7
SYMATTR Value 212k
SYMBOL nmos 608 48 R0
SYMATTR InstName M2
SYMATTR Value 2N7002
SYMBOL res 400 -48 R0
SYMATTR InstName R6
SYMATTR Value 46k4
SYMBOL cap 368 -80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 100nF
SYMBOL ind 944 160 R0
SYMATTR InstName L1
SYMATTR Value 60mH
SYMATTR SpiceLine Ipk=20 Rser=2
SYMBOL schottky 848 352 R180
WINDOW 0 2 60 Right 2
WINDOW 3 4 1 Right 2
SYMATTR InstName D1
SYMATTR Value RBR30T60A
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 816 160 R0
SYMATTR InstName R5
SYMATTR Value 0R1
TEXT 16 176 Left 3 !.tran 0 3 0 0.001
TEXT 1032 -184 Right 3 ;Alternate Part - DMP3007SCG
TEXT 176 -144 Right 3 ;From MCU
TEXT -392 -88 Left 3 ;Motor Controller\\nCurrent Sense Output
TEXT 32 416 Left 2 ;Alternate Parts -\\nLMC6772 in SOIC8 or VSSOP8\\nTLV1702 in VSSOP8 \\nTLV1704 in TSSOP14 (quad) <--- lowest cost per unit
TEXT 456 368 Left 3 ;~100 ms trip time
TEXT 152 -96 Center 3 ;ON
TEXT 152 -32 Center 3 ;OFF
TEXT 136 8 Center 3 ;10 ms setup required
TEXT 304 80 Right 3 ;Status to MCU
TEXT 544 432 Left 3 ;Alternate Part - STPS20M100SG
TEXT 328 -272 Right 4 ;Motor Overcurrent Shutoff
TEXT -304 304 Left 3 ;1.26 volts
LINE Normal 864 0 928 -160
LINE Normal 48 -80 16 -80
LINE Normal 64 -112 48 -80
LINE Normal 96 -112 64 -112
LINE Normal 64 -112 96 -112
LINE Normal 48 -96 64 -112
LINE Normal 64 -96 48 -96
LINE Normal 64 -112 64 -96
LINE Normal 64 -16 48 -48
LINE Normal 96 -16 64 -16
LINE Normal 64 -16 96 -16
LINE Normal 48 -32 64 -16
LINE Normal 64 -32 48 -32
LINE Normal 64 -16 64 -32
LINE Normal 48 -48 16 -48
LINE Normal 816 352 768 416

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
 
I pushed the transistor version around until I found a couple more optimizations and I think that is the better circuit now. No new parts added to the BoM other than the P-MOSFET needed to handle the motor current.

I optimized it by not using the PFET as part of the FF since that made the FF all 15 volt logic which was hard to interface to the low voltage circuit.. I could use two NFETs to make the FF on the low voltage rail, but the final optimization was to eliminate the NFET interfacing the timing RC by putting the OC comparator output in series with one of the NFETs. That created an OR gate to allow the transistor to accept two inputs.

I added two resistors in the load of the other NFET so there was a node the MCU can pull up or down through a cap to turn the motor back on or to turn it off although that should not be needed as there is a motor controller to handle that. This circuit is kill the motor power if it goes to the stops too long.

I\'m pretty happy with the result and no logic chip required.

Here is the LTspice circuit if anyone cares to see it.

Version 4
SHEET 1 1752 708
WIRE -688 -256 -704 -256
WIRE -704 -240 -704 -256
WIRE 416 -192 400 -192
WIRE 416 -176 416 -192
WIRE 656 -112 640 -112
WIRE -688 -96 -704 -96
WIRE -496 -96 -512 -96
WIRE 656 -96 656 -112
WIRE -704 -80 -704 -96
WIRE -496 -80 -496 -96
WIRE 256 -64 240 -64
WIRE 304 -64 256 -64
WIRE 416 -64 416 -96
WIRE 416 -64 368 -64
WIRE 480 -64 416 -64
WIRE 560 -64 480 -64
WIRE 832 -48 816 -48
WIRE 416 -32 416 -64
WIRE -288 0 -320 0
WIRE -48 0 -288 0
WIRE 832 0 832 -48
WIRE 656 16 656 -16
WIRE 656 16 512 16
WIRE 736 16 656 16
WIRE 784 16 736 16
WIRE -320 32 -320 0
WIRE -496 48 -496 0
WIRE -432 48 -496 48
WIRE -368 48 -432 48
WIRE 656 48 656 16
WIRE -688 64 -704 64
WIRE -704 80 -704 64
WIRE 352 80 320 80
WIRE 416 80 416 48
WIRE 416 80 352 80
WIRE -496 96 -496 48
WIRE -368 96 -400 96
WIRE -400 112 -400 96
WIRE 416 112 416 80
WIRE -320 128 -320 112
WIRE 560 128 560 -64
WIRE 608 128 560 128
WIRE 832 144 832 96
WIRE 912 144 832 144
WIRE 960 144 912 144
WIRE -144 176 -160 176
WIRE 832 176 832 144
WIRE 960 176 960 144
WIRE -496 192 -496 176
WIRE -496 192 -512 192
WIRE -144 192 -144 176
WIRE 512 192 512 16
WIRE 512 192 464 192
WIRE -688 224 -704 224
WIRE 416 224 416 208
WIRE -704 240 -704 224
WIRE 96 256 80 256
WIRE 768 272 752 272
WIRE 832 272 832 256
WIRE 832 272 768 272
WIRE 96 288 96 256
WIRE 832 288 832 272
WIRE 960 288 960 256
WIRE -144 304 -144 272
WIRE 16 304 -144 304
WIRE 64 304 16 304
WIRE 208 320 128 320
WIRE 272 320 208 320
WIRE 400 320 352 320
WIRE 464 320 400 320
WIRE 656 320 656 144
WIRE 656 320 464 320
WIRE -144 336 -144 304
WIRE -48 336 -48 0
WIRE 16 336 -48 336
WIRE 64 336 16 336
WIRE 400 352 400 320
WIRE -560 368 -576 368
WIRE -48 368 -48 336
WIRE 96 368 96 352
WIRE -576 384 -576 368
WIRE 832 384 832 352
WIRE -688 432 -704 432
WIRE -144 432 -144 416
WIRE 400 432 400 416
WIRE -704 448 -704 432
WIRE -48 480 -48 448
FLAG 96 368 0
FLAG -48 480 0
FLAG -704 432 SIG
FLAG -704 224 NOISE
FLAG -704 528 0
FLAG -704 320 0
FLAG -496 -96 SIG
FLAG -496 192 NOISE
FLAG -288 0 Input
FLAG 16 336 U1+
FLAG 208 320 SIXAMPS
FLAG -320 128 0
FLAG -400 112 0
FLAG -144 432 0
FLAG 16 304 VREF
FLAG -144 176 3V3
FLAG 400 432 0
FLAG -432 48 SUM
FLAG -704 160 0
FLAG -704 64 3V3
FLAG -704 0 0
FLAG -704 -96 5V
FLAG 656 -112 VIN
FLAG 736 16 OFF
FLAG 832 -48 VIN
FLAG -576 464 0
FLAG -576 368 VIN
FLAG 352 80 ON
FLAG 416 224 0
FLAG 96 256 3V3
FLAG -704 -160 0
FLAG -704 -256 MOT_ON
FLAG 416 -192 3V3
FLAG 256 -64 MOT_ON
FLAG 464 320 OVR
FLAG 480 -64 FORCE
FLAG 960 288 0
FLAG 912 144 VMOT
FLAG 832 384 0
FLAG 768 272 DIODE
SYMBOL voltage -704 64 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V1
SYMATTR Value 3.3
SYMBOL res -64 352 R0
SYMATTR InstName R3
SYMATTR Value 1.5K
SYMBOL voltage -704 432 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 24 96 Left 1
SYMATTR Value PWL(0 0 0.5 0 0.51 4 1 4 1.005 8 1.05 8 1.055 4 1.1 4 1.105 8 1.15 8 1.155 4 1.2 4 1.205 8 1.25 8 1.255 4 1.3 4 1.305 8 1.35 8 1.355 4 1..4 4 1.405 8 1.45 8 1.455 4 1.5 4 1.505 8 1.55 8 1.555 4 1.6 4 1.605 8 2 8 2.005 4 2.6 4 2.605 8)
SYMATTR InstName V2
SYMBOL bv -704 224 R0
SYMATTR InstName B1
SYMATTR Value V=0.2*(white(2e1*time))
SYMBOL res -512 -96 R0
SYMATTR InstName R10
SYMATTR Value 1k
SYMBOL res -512 80 R0
SYMATTR InstName R11
SYMATTR Value 100k
SYMBOL res -160 176 R0
SYMATTR InstName R1
SYMATTR Value 1Meg
SYMBOL g -320 16 R0
WINDOW 3 16 98 Left 2
SYMATTR Value 142.25E-6
SYMATTR InstName G1
SYMBOL cap 384 352 R0
SYMATTR InstName C1
SYMATTR Value 22µF
SYMBOL Comparators\\\\LTC1841 96 320 R0
WINDOW 3 25 58 Left 2
SYMATTR InstName U1
SYMBOL res 368 304 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 1k
SYMBOL res -160 320 R0
SYMATTR InstName R2
SYMATTR Value 620k
SYMBOL voltage -704 -96 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL res 640 -112 R0
SYMATTR InstName R8
SYMATTR Value 46k4
SYMBOL pmos 784 96 M180
SYMATTR InstName M3
SYMATTR Value AOD4185
SYMBOL voltage -576 368 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V4
SYMATTR Value PULSE(0 14.7 0.01 0.02 0.12 15)
SYMBOL nmos 464 112 M0
SYMATTR InstName M1
SYMATTR Value 2N7002
SYMBOL voltage -704 -256 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0.01
SYMATTR InstName V5
SYMATTR Value PULSE(3.3 00 0.1 10us 10us 0.01 2.4)
SYMBOL res 400 -192 R0
SYMATTR InstName R7
SYMATTR Value 212k
SYMBOL nmos 608 48 R0
SYMATTR InstName M2
SYMATTR Value 2N7002
SYMBOL res 400 -48 R0
SYMATTR InstName R6
SYMATTR Value 46k4
SYMBOL cap 368 -80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 100nF
SYMBOL ind 944 160 R0
SYMATTR InstName L1
SYMATTR Value 60mH
SYMATTR SpiceLine Ipk=20 Rser=2
SYMBOL schottky 848 352 R180
WINDOW 0 2 60 Right 2
WINDOW 3 4 1 Right 2
SYMATTR InstName D1
SYMATTR Value RBR30T60A
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 816 160 R0
SYMATTR InstName R5
SYMATTR Value 0R1
TEXT 16 176 Left 3 !.tran 0 3 0 0.001
TEXT 1032 -184 Right 3 ;Alternate Part - DMP3007SCG
TEXT 176 -144 Right 3 ;From MCU
TEXT -392 -88 Left 3 ;Motor Controller\\nCurrent Sense Output
TEXT 32 416 Left 2 ;Alternate Parts -\\nLMC6772 in SOIC8 or VSSOP8\\nTLV1702 in VSSOP8 \\nTLV1704 in TSSOP14 (quad) <--- lowest cost per unit
TEXT 456 368 Left 3 ;~100 ms trip time
TEXT 152 -96 Center 3 ;ON
TEXT 152 -32 Center 3 ;OFF
TEXT 136 8 Center 3 ;10 ms setup required
TEXT 304 80 Right 3 ;Status to MCU
TEXT 544 432 Left 3 ;Alternate Part - STPS20M100SG
TEXT 328 -272 Right 4 ;Motor Overcurrent Shutoff
TEXT -304 304 Left 3 ;1.26 volts
LINE Normal 864 0 928 -160
LINE Normal 48 -80 16 -80
LINE Normal 64 -112 48 -80
LINE Normal 96 -112 64 -112
LINE Normal 64 -112 96 -112
LINE Normal 48 -96 64 -112
LINE Normal 64 -96 48 -96
LINE Normal 64 -112 64 -96
LINE Normal 64 -16 48 -48
LINE Normal 96 -16 64 -16
LINE Normal 64 -16 96 -16
LINE Normal 48 -32 64 -16
LINE Normal 64 -32 48 -32
LINE Normal 64 -16 64 -32
LINE Normal 48 -48 16 -48
LINE Normal 816 352 768 416

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
 
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