Version 4
SHEET 1 1388 680
WIRE 192 0 -48 0
WIRE 192 64 192 0
WIRE -48 176 -48 0
WIRE 192 208 192 144
WIRE 288 208 192 208
WIRE 400 208 368 208
WIRE 192 288 192 208
WIRE -48 368 -48 256
WIRE 192 368 192 352
WIRE 192 368 -48 368
WIRE 192 400 192 368
FLAG 192 400 0
FLAG 400 208 #RESET
IOPIN 400 208 In
SYMBOL res 176 48 R0
SYMATTR InstName R1
SYMATTR Value 100
SYMBOL cap 176 288 R0
SYMATTR InstName C1
SYMATTR Value 10µ
SYMBOL res 384 192 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL voltage -48 160 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
TEXT -1112 224 Left 2 ;Constraints:\nVoltage source that MCP2515 accepts is 5 V.\nThe minimum operating voltage is 2.7 V.\nTo ensure this happens with a comfortable margin, we will design #RESET\nto remain below 2.7 V for at least 10 microseconds.
TEXT -1112 -40 Left 2 ;Problem:\n(Taken from MCP2515 Datasheet [Page 57])\nIt is important to provide a RESET signal after power-up to ensure that the logic\nand registers are in their default state. A hardware Reset can be achieved\nautomatically by placing an RC on the #RESET pin (See Figure 9-1).\nThe values must be such that the device is held in Reset for a minimum of\n2 microseconds after V_DD reaches the operating voltage, as indicated\nin the electrical specification (t_RL).
TEXT -1112 424 Left 2 !.tran 0 0.001 0 startup
TEXT 424 0 Left 2 ;Result:\nThis way over-satisfies the requirements, but will stay with this since the parts are\nprobably cheapest, just lying around somewhere in these values.