Ethernet & USB Clock Generator for
Freescale B4/T4-based Systems
840NT4-01
DATA SHEET
General Description
Features
The 840NT4-01 is clock generator designed to provide ethernet and
USB clocks for Freescale B4/ T4-based systems. The 840NT4-01
utilizes IDT’s FemtoClock NG® PLL technology to synthesize eight
low phase-jitter Ethernet reference clocks. The clock generator also
provides a 24MHz USB reference clock and a 25MHz reference
output.
• Ten LVCMOS clock outputs:
Five LVCMOS 125MHz Ethernet outputs
Three LVCMOS 25MHz /125MHz Ethernet outputs
One LVCMOS 24MHz USB output
One LVCMOS 25MHz REF output
• QREF output can be used to drive other clock drivers, saving a
crystal
Recommended Application:
• Selectable crystal or differential LVPECL input
• Freescale B4/ T4 Ethernet /USB clock generator
• RMS Phase Jitter, 125MHz, integration range 12kHz - 20MHz:
0.60ps (typical)
Output Features:
• Five LVCMOS 125MHz Ethernet outputs
• Cycle-to-Cycle jitter: 20ps (typical)
• Three LVCMOS 25MHz/ 125MHz Ethernet outputs
• One LVCMOS 24MHz USB output
• Flexible voltage supply modes; supports legacy and future system
requirements, minimizes power consumption
Core voltage: VDD, VDD_XTAL, VDDA
• One LVCMOS 25MHz REF output
Output voltage: VDDO_A, VDDO_B, VDDO_C, VDDO_REF
Core / Output
3.3V / 3.3V
3.3V / 2.5V
3.3V / 1.8V
2.5V / 2.5V
2.5V / 1.8V
• -40°C to 85°C ambient operating temperature
• Lead-free (RoHS 6) packaging
Pin Assignment
Table 1. Output Frequency Table
F
(MHz)
OUT
PD* PLL_ PLL_
(MHz) PSELB SELA SELB QA[4:0] QB[2:0] QC QREF
36 35 34 33 32 31 30 29 28 27 26 25
25
25
25
25
0
1
0
1
0
0
0
0
0
0
1
1
125
125
125
125
125
125
25
24
24
24
24
25
25
25
25
VDD
37
38
39
40
24
23
22
21
20
19
18
17
16
15
14
13
GND_QB
VDDO_B
QB0
PSELB
PLL_SELA
PLL_SELB
GNDA
QB1
25
41
42
43
44
45
46
QB2
840NT4-01
VDDA
VDDO_B
OE_B
*PD = Phase Detector input frequency.
GND
VDD
VDDO_C
QC
RESERVED
VDD
GND_QC
OE_C
XTAL_SEL
GND_XTAL
47
48
GND_REF
1
2 3 4 5 6 7 8 9 10 11 12
48-lead, 7.0mm x 7.0mm VFQFN
REVISION 2 05/18/15
1
©2015 Integrated Device Technology, Inc.