Datasheet

A1
A1
C B
A
T
LPDDR
Controller
Microprocessor
AM3517, AM3505
www.ti.com SPRS550E –OCTOBER 2009–REVISED MARCH 2013
Table 6-19. LPDDR Signal Terminations
NO. PARAMETER MIN TYP MAX UNIT NOTES
1 CK Net Class 0 10 Ω See Note
(1)
2 ADDR_CTRL Net Class 0 22 Zo Ω See Notes
(1)
,
(2)
,
(3)
Data Byte Net Classes
3 0 22 Zo Ω See Notes
(1)
,
(2)
,
(3)
(DQS0-DQS3, DQ0-DQ3)
(1) Only series termination is permitted, parallel or SST specifically disallowed.
(2) Terminator values larger than typical only recommended to address EMI issues.
(3) Termination value should be uniform across net class.
6.4.2.1.8 LPDDR CK and ADDR_CTRL Routing
Figure 6-21 shows the topology of the routing for the CK and ADDR_CTRL net classes. The route is a
balanced T as it is intended that the length of segments B and C be equal. In addition, the length of A
should be maximized.
Figure 6-21. CK and ADDR_CTRL Routing and Topology
Table 6-20. CK and ADDR_CTRL Routing Specification
NO. PARAMETER MIN TYP MAX UNIT NOTES
1 Center to Center CK-CK spacing 2w
2 CK A to B/A to C Skew Length Mismatch 25 Mils See Note
(1)
3 CK B to C Skew Length Mismatch 25 Mils
Center to Center CK to other
4 4w See Note
(2)
LPDDR trace spacing
5 CK/ADDR_CTRL nominal trace length CACLM-50 CACLM CACLM+50 Mils See Note
(3)
6 ADDR_CTRL to CK Skew Length Mismatch 100 Mils
ADDR_CTRL to ADDR_CTRL
7 100 Mils
Skew Length Mismatch
Center to Center ADDR_CTRL to other
8 4w See Note
(2)
LPDDR trace 4w spacing
Center to Center ADDR_CTRL to other
9 3w See Note
(2)
ADDR_CTRL 3w trace spacing
ADDR_CTRL A to B/A to C Skew Length
10 100 Mils See Note
(1)
Mismatch
11 ADDR_CTRL B to C Skew Length Mismatch 100 Mils
(1) Series terminator, if used, should be located closest to device.
(2) Center to center spacing is allowed to fall to minimum (w) for up to 500 mils of routed length to accommodate BGA escape and routing
congestion.
(3) CACLM is the longest Manhattan distance of the CK and ADDR_CTRL net classes.
Copyright © 2009–2013, Texas Instruments Incorporated Timing Requirements and Switching Characteristics 135
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