Measured on the LP-EM-CC2745R10-Q1 reference design with Tc = 25°C, VDDS = 3.0V, unless otherwise noted.
|
PARAMETER |
MIN |
TYP |
MAX |
UNIT |
|
Crystal frequency |
|
48 |
|
MHz |
| gm |
Oscillator Transconductance(1) |
|
16.5 |
|
mA/V |
| ESR |
Equivalent series resistance(2)(3) CL = 9 pF, C0 ≤ 1pF |
|
|
45 |
Ω |
Equivalent series resistance(2)(3) CL = 8 pF, C0 ≤ 1pF |
|
|
55 |
Ω |
Equivalent series resistance(2)(3) CL = 7 pF, C0 ≤ 1pF |
|
|
70 |
Ω |
Equivalent series resistance(2)(3) 5 pF < CL ≤ 6 pF, C0 ≤ 1pF |
|
|
90 |
Ω |
| CL |
Crystal load capacitance(4) |
5 |
7(5) |
9 |
pF |
| Start-up time(6) |
Until clock is qualified. |
|
130 |
|
µs |
(1) Negative resistance is the oscillator's ability to counteract the losses in the crystal, thereby sustaining oscillations at the crystal's resonant frequency.
Negative resistance RN = -gm/((2*π*f)
2 * (2*(CL+C0))
2). RN corresponds to the total series resistance (ESR + additional series R) that prevents the oscillations from starting at the XTAL pins. XTAL startup margin = RN / ESRmax. For more information, see App Note
SWRA495.
(2) The max ESR value will be reduced if the crystal has a shunt capacitance of C0 > 1pF
(3) XTAL startup margin ≥10
(4) Adjustable load capacitance is integrated into the device. External load capacitors are required for systems targeting compliance with certain regulations.
(5) On-chip default connected capacitance including reference design parasitic capacitance. Connected internal capacitance is changed through software in the Customer Configuration section (CCFG).
(6) Start-up time using the TI-provided power driver. Start-up time may increase if the driver is not used.