Datasheet
TUSB7320, TUSB7340
www.ti.com
SLLSE76E–MARCH 2011– REVISED JULY 2011
9.2 External clock
When using an external clock source, the reference clock should have a ±100 PPM or better frequency
stability and have less than 50-ps absolute peak to peak jitter or less than 25-ps peak to peak jitter after
applying the USB 3.0 jitter transfer function. XI should be tied to the clock source and XO should be left
floating. The input clock must be 1.8-V LVCMOS; this input is not 3.3-V tolerant. When AUX_DET is high
and the TUSB73x0 is in D3cold the TUSB73x0 utilizes an internal ring oscillator to support wake from
D3cold eliminating the need to keep the external clock active while in D3cold.
Table 9-1. Input Clock Specification
PARAMETER CONDITION MIN TYP MAX UNIT
Frequency Tolerance Operational Temperature ±50 ppm
Frequency Stability 1 year aging ±100 ppm
Rise / Fall Time 20% - 80% 6 ns
Reference Clock R
J
with
0.8 ps
JTF (1 sigma)
(1)(2)
Reference Clock T
J
with
25 ps
JTF (total p-p)
(2)(3)
Reference Clock Jitter
50 ps
(absolute p-p)
(4)
(1) Sigma value assuming Gaussian distribution.
(2) After application of JTF.
(3) Calculated as 14.1 x R
J
+D
J
(4) Absolute phase jitter (p-p)
Table 9-2. Input Clock 1.8-V DC Characteristics
PARAMETER CONDITION MIN TYP MAX UNIT
VIH High-level input voltage 0.65 V
DDS
V
VIL Low-level input voltage 0.35 V
DDS
V
I
O
= -2 mA, V
DDS
= 1.62 to 1.98 V,
V
DDS
-0.45
driver enabled, pullup or pulldown disabled
VOH V
I
O
= -2 mA, V
DDS
= 1.4 to 1.6 V,
0.75 V
DDS
driver enabled, pullup or pulldown disabled
I
O
= 2 mA, driver enabled, V
DDS
= 1.62 to 1.98 V,
0.45
pullup or pulldown disabled
VOL V
I
O
= 2 mA, V
DDS
= 1.4 to 1.6 V,
0.25 V
DDS
driver enabled, pullup or pulldown disabled
9.3 External crystal
An external 1-MΩ feedback resistor is required between XI and XO when using a crystal. See the table
below for additional crystal specifications.
Table 9-3. Crystal Specification
PARAMETER CONDITION MIN TYP MAX UNIT
Frequency Tolerance Operational Temperature ±50 ppm
Frequency Stability 1 year aging ±100 ppm
Load Capacitance 12 24 pF
ESR 50 Ω
Copyright © 2011, Texas Instruments Incorporated INPUT CLOCK 103
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Product Folder Link(s): TUSB7320 TUSB7340