TMS320F28379S Datasheet, PDF (65/209 Pages) Texas Instruments – Microcontrollers

www.ti.com
TMS320F28379S, TMS320F28377S
TMS320F28376S, TMS320F28375S, TMS320F28374S
SPRS881B – AUGUST 2014 – REVISED OCTOBER 2015
5.7.3.4 Crystal Oscillator
When using a quartz crystal, it may be necessary to include a damping resistor (R_D) in the crystal circuit to
prevent over-driving the crystal (drive level can be found in the crystal data sheet). In higher-frequency
applications (10 MHz or greater), R_D is generally not required. If a damping resistor is required, R_D should
be as small as possible because the size of the resistance affects start-up time (smaller R_D = faster start-
up time). It is recommended that the crystal manufacturer characterize the crystal with the application
board.
Table 5-15. Crystal Oscillator Parameters
CL1, CL2
C0
Load capacitance
Crystal shunt capacitance
MIN MAX UNIT
12
24 pF
7 pF
Table 5-16. Crystal Equivalent Series Resistance (ESR) Requirements⁽¹⁾⁽²⁾
CRYSTAL FREQUENCY (MHz)
MAXIMUM ESR (Ω)
(CL1 = CL2 = 12 pF)
10
55
12
50
14
50
16
45
18
45
20
45
(1) Crystal shunt capacitance (C0) should be less than or equal to 7 pF.
(2) ESR = Negative Resistance/3
MAXIMUM ESR (Ω)
(CL1 = CL2 = 24 pF)
110
95
90
75
65
50
Table 5-17. Crystal Oscillator Electrical Characteristics
over recommended operating conditions (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX UNIT
Start-up time⁽¹⁾
f = 20 MHz
ESR MAX = 50 Ω
CL1 = CL2 = 24 pF
C0 = 7 pF
2
ms
Crystal drive level (DL)
1 mW
(1) Start-up time is dependent on the crystal and tank circuit components. It is recommended that the crystal vendor characterize the
application with the chosen crystal.
Copyright © 2014–2015, Texas Instruments Incorporated
Specifications
65
Submit Documentation Feedback
Product Folder Links: TMS320F28379S TMS320F28377S TMS320F28376S TMS320F28375S TMS320F28374S