fs-ulx3s/spice/powersection.spice

* POWERSECTION -> plot v(pwrbtn_pulse),v(shutdown_pulse),v(wake_pulse),v(p3v3),v(ftdi_nsleep)

* Simulation of power network
* POWER ON: USB plugged in, POWER button, RTC alarm, FTDI_nSLEEP
* POWER OFF: SHUTDOWN signal
* FTDI_nSLEEP has priority over SHUTDOWN signal (not yet simulated)

*  Simulate 5V USB plugging in every 10 seconds
*                                       start  rise  fall  duration  period
VUSB5V hard_5V 0         PULSE(0V    5V  0.1s  10ms  10ms        9s     10s DC=0V)
* internal resistor provides "soft" USB 5V
Rusb hard_5V USB5V 0.1

*  shutdown pulse every 1 second, start after 0.4s
*                                       start  rise  fall  duration  period
VSHUT shutdown_pulse  0  PULSE(0V  3.3V  0.4s  10ms  10ms     100ms      1s DC=0V)
* convergence friendly resistor
RSHUT shutdown_pulse SHUTDOWN 220

*  power up button pulse every 10 seconds, start after 0.7s
*                                       start  rise  fall  duration  period
VPWRBTN pwrbtn_pulse  0  PULSE(0V  3.3V  0.9s  10ms  10ms     100ms     10s DC=0V)

* RTC internal wakeup pulse every 10 seconds, start after 1.7s
*                                       start  rise  fall  duration  period
VWAKEUP wake_pulse  0  PULSE(0V  3.3V    1.9s  10ms  10ms     100ms     10s DC=0V)
* convergence friendly internal resistor
Rwk  wake_pulse wake_base  1k

*  FTDI_nSLEEP signal every 10 seconds, start after 2.3s
*                                       start  rise  fall  duration  period
VFTDI FTDI_nSLEEP   0    PULSE(0V  3.3V  2.2s  10ms  10ms      0.5s     10s DC=0V)

* RTC internal NPN transisfor for open collector output
Qwk  WAKEUPn wake_base 0  BC847

* hard 3.3V voltage
Vhard3V3 hard_3V3 0 3.3V
* internal resistor provides "soft" 3.3V
Rsmps hard_3V3 PWR3V3 10

* base resistor
R6 WAKEUPn WKn 1k
* PNP transistor
Q1 WKUP WKn USB5V BC857
* Slow down capacitor, initially discharged
C13 USB5V WKUP 2.2uF IC=0
* diode to discharge C13 at shutdown
D13 0 WKUP N4148

* diode to activate onboard switching regulator
D10 WKUP WAKE N4148
* "OR" resistors
R1 WAKE PWREN 15k
R4 PWREN HOLD 15k
* "OR" diode to 3.3V from switching regulator
D11 P3V3 HOLD N4148

* switching regulator, default off, starts by hysteresis
SW3V3 PWR3V3 P3V3 PWREN 0 SWITCH OFF

* pull down resistor
R2 PWREN 0 47k

* small mosfet
M1 drain SHUT 0 0 N7002
* drain resistor
R8 drain PWREN 1k
* mosfet gate slowdown resistor
C14 SHUT 0 100nF
* mosfet gate discharge (default OFF) resistor
R5 SHUT 0 4.7MEG

* diode to discharge gate at shutdown
D14 SHUT P3V3 N4148

* diode for shutdown to only pull down, never up
D15 SHUTDOWN SHUT BAT42
* Pull down resistor
R13 SHUTDOWN 0 15k

* power button
R3 USB5V pwrbtn 4.7k
D16 WAKEUPn pwrbtn N4148
SPWR pwrbtn 0  pwrbtn_pulse 0  SWITCH OFF

* ftdi no-sleep network
R10 FTDI_nSLEEP FTDI_nSUSPEND 220
D12 FTDI_nSUSPEND PWREN N4148


* The load (slow)
RL P3V3 0   100
CL P3V3 0   1000uF


.TRAN 1ms 3s
.OPTIONS METHOD=GEAR, RELTOL=1E-3, itl1=500, itl4=500
*.OPTIONS gmin=1e-11 reltol=4e-4 itl1=500 itl4=500
*.OPTIONS gmin = 1E-12, reltol = 1E-3, itl1 = 500, itl4 = 500 

.MODEL SWITCH SW (VT=1V, VH=0.5V, RON=0.01, ROFF=100MEG)
.MODEL N4148 D (CJO=0.2pF)
.MODEL BAT42 D (VJ=0.25)
.MODEL BC847 NPN (BF=150)
.MODEL BC857 PNP (BF=150)
.MODEL N7002 NMOS (LEVEL=1, VTO=2.5, KP=40, RS=0.033, RD=0.034)

* todo
* [ ] BAT42 schottky diode model doesn't simulate wanted 0.25V drop
*     the BAT42 model seems to have 0.7V drop
* [ ] delay: switch power 3.3V doesn't start immediately
* [ ] control signals should be derived from P3V3 line