
Electrical Specifications
USB Low-Speed Source Electrical Characteristics
MC68HC908JB8MC68HC08JB8MC68HC08JT8 — Rev. 2.3
Technical Data
Freescale Semiconductor
Electrical Specifications
259
18.10 USB Low-Speed Source Electrical Characteristics
Characteristic(1)
NOTES:
1. All voltages are measured from local ground, unless otherwise specified. All timings use a capacitive load of 50 pF, unless
otherwise specified. Low-speed timings have a 1.5k
pullup to 2.8 V on the D– data line.
Symbol
Conditions
Min
Typ
Max
Unit
Internal operating frequency
fOP
——
3
—
MHz
Transition time(2)
Rise time
Fall time
2. Transition times are measured from 10% to 90% of the data signal. The rising and falling edges should be smoothly tran-
sitioning (monotonic). Capacitive loading includes 50 pF of tester capacitance.
tR
tF
CL = 200 pF
CL = 600pF
CL = 200 pF
CL = 600pF
75
—
300
ns
Rise/Fall time matching
tRFM
tR/tF
80
—
120
%
Low speed data rate
tDRATE
1.5 Mbs
± 1.5%
1.4775
676.8
1.500
666.0
1.5225
656.8
Mbs
ns
Source differential driver jitter
To next transition
For paired transitions
tDDJ1
tDDJ2
CL = 600 pF
Measured at
crossover point
–25
–10
—
25
10
ns
Receiver data jitter tolerance
To next transition
For paired transitions
tDJR1
tDJR2
CL = 600 pF
Measured at
crossover point
–75
–45
—
75
45
ns
Source SEO interval of EOP
tLEOPT
Measured at
crossover point
1.25
—
1.50
s
Source jitter for differential transition
to SE0 transition(3)
3. The two transitions are a (nominal) bit time apart.
Measured at
crossover point
667
ns
Receiver SEO interval of EOP
Must reject as EOP
Must accept
tLEOPR1
tLEOPR2
Measured at
crossover point
210
670
—
ns
Width of SEO interval during
differential transition
tLST
Measured at
crossover point
——
210
ns