Electrical Specifications
Control Timing
MC68HC908JB8MC68HC08JB8MC68HC08JT8 — Rev. 2.3
Technical Data
Freescale Semiconductor
Electrical Specifications
257
18.7 Control Timing
18.8 Oscillator Characteristics
NOTES:
1. VDD = 4.0 to 5.5 Vdc, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25
°C only.
3. Run (operating) IDD measured using external square wave clock source (fXCLK = 6 MHz). All inputs 0.2 V from rail. No dc
loads. Less than 100 pF on all outputs. CL = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly
affects run IDD. Measured with all modules enabled.
4. Wait IDD measured using external square wave clock source (fXCLK = 6 MHz); all inputs 0.2 V from rail; no dc loads; less
than 100 pF on all outputs. CL = 20 pF on OSC2; 15 k ± 5% termination resistors on D+ and D– pins; all ports configured
as inputs; OSC2 capacitance linearly affects wait IDD
5. STOP IDD measured with USB in suspend mode; OSC1 grounded; transceiver pullup resistor of 1.5 k ± 5% between VREG
and D– and 15 k
± 5% termination resistors on D+ and D– pins; no port pins sourcing current.
6. Maximum is highest voltage that POR is guaranteed.
7. If minimum VREG is not reached before the internal POR reset is released, RST must be driven low externally until minimum
VREG is reached.
Characteristic(1)
NOTES:
1. VDD = 4.0 to 5.5 Vdc; VSS = 0 Vdc; timing shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
Symbol
Min
Max
Unit
Internal operating frequency(2)
2. Some modules may require a minimum frequency greater than dc for proper operation; see appropriate table for this infor-
mation.
fOP
—3
MHz
RST input pulse width low(3)
3. Minimum pulse width reset is guaranteed to be recognized. It is possible for a smaller pulse width to cause a reset.
tIRL
125
—
ns
Characteristic
Symbol
Min
Typ
Max
Unit
Crystal frequency(1)
NOTES:
1. The USB module is designed to function at fXCLK = 6 MHz.
fXCLK
1—
6
MHz
External clock
Reference frequency(1), (2)
2. No more than 10% duty cycle deviation from 50%.
fXCLK
dc
—
6
MHz
Crystal load capacitance(3)
3. Consult crystal vendor data sheet.
CL
——
—
Crystal fixed capacitance(3)
C1
—
2
× C
L
—
Crystal tuning capacitance(3)
C2
—
2
× C
L
—
Feedback bias resistor
RB
—10 M
—
Series resistor(3), (4)
4. Not required for high-frequency crystals.
RS
——
—