PTN3700 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 3 — 12 October 2011 32 of 43
NXP Semiconductors
PTN3700
1.8 V simple mobile interface link bridge IC
12.3 Power decoupling configuration
The PTN3700 needs 1.8 V V
DD
and 1.8 V V
DDA
. Both can share the same voltage
regulator, and use a 10 resistor for isolation. The recommended power configuration of
the decoupling is shown in Figure 25
. It is recommended to install one 0.1 F ceramic
capacitor for each VDD pin and one 0.01 F ceramic capacitor for VDDA pin, and the lead
length between the IC power pins and decoupling capacitors should be as short as
possible.
12.4 PCB/Flex layout guideline
The high data rate at the serial I/O requires some specific implementations in the PCB and
flex layout design. The following practices can be used as guideline:
• The differential pair must be routed symmetrically. Keep all four pairs of differential
signal traces the same length. The difference in trace length should be less than
20 mils.
• Maintain 100 differential impedance.
• Do not route signals over any plane split; use only one ground plane underneath the
differential signals.
• Avoid any discontinuity for signal integrity. Differential pairs should be routed on the
same layer and the number of vias on the differential traces should be minimized. Test
points should be placed in series and symmetrically. Stubs should not be introduced
on the differential pairs.
12.5 Power-on/power-off requirement
PTN3700 does not have any external reset pin. Internally, there is Power-On Reset (POR)
circuitry to reset the whole IC at power-up. In order to guarantee that POR works properly,
the supply voltage V
DD
must be powered up from ground level, as illustrated in Figure 26.
Fig 25. Power decoupling configuration
VDD
0.1 μF 0.1 μF 0.1 μF
10 Ω
0.01 μF
VDDA
002aac937
Fig 26. Expected and unexpected power-on behavior
002aag311
Expected behavior.
Power-up from GND level enables
PTN3700 to start up correctly with
stable POR.
Unexpected behavior.
Power-up from a higher than GND level
might set PTN3700 to an unstable state
without proper POR.
V
DD
GND
