nvt2001 NXP Semiconductors, nvt2001 Datasheet - Page 9

• Manufacturer Part Number: nvt2001
• Description: Bidirectional Voltage Level Translator For Open-drain And Push-pull Applications
• Manufacturer: NXP Semiconductors

NXP Semiconductors
8. Limiting values
NVT2001_NVT2002
Product data sheet
7.3.1.1 Example maximum frequency
chip/terminating end of the wire when the transition time is shorter than the time of flight of
the wire because the NVT20xx looks like a high-impedance compared to the wire. If the
wire is not too long and the lumped capacitance is not excessive the signal will only be
slightly degraded by the series resistance added by passing through the NVT20xx. If the
lumped capacitance is large the rise time will deteriorate, the fall time is much less
affected and if the rise time is slowed down too much the duty cycle of the clock will be
degraded and at some point the clock will no longer be useful. So the principle design
consideration is to minimize the wire length and the capacitance on the 1.8 V side for the
clock path. A pull-up resistor on the 1.8 V side can also be used to trade a slower fall time
for a faster rise time and can also reduce the overshoot in some cases.
Question — We need to make the PLL area of a new line card backwards compatible and
need to need to convert one GTL signal to LVTTL, invert it, and convert it back to GTL.
The signal we want to convert is random in nature but will mostly be around 19 MHz with
very long periods of inactivity where either a HIGH or LOW state will be maintained. The
traces are 1 or 2 inches long with trace capacitance of about 2 pF per inch.
Answer — The frequency of the NVT20xx is limited by the capacitance of the part, the
capacitance of the traces and the pull-up resistors used. The limiting case is probably the
LOW-to-HIGH transition in the GTL to LVTTL direction, and there the use of the lowest
acceptable resistor values will minimize the rise time delay. Assuming 50 pF capacitance
and 220 Ω resistance, the RC time constant is 11 ns (50 pF × 220 Ω). With 19 MHz
corresponding to 50 ns period the NVT20xx will support this application.
Table 6.
In accordance with the Absolute Maximum Rating System (IEC 60134).
Over operating free-air temperature range.
[1]
[2]
Symbol
V
V
V
V
I
I
I
T
ch
IK
OK
stg
ref(A)
ref(B)
I
I/O
The input and input/output negative voltage ratings may be exceeded if the input and input/output clamp
current ratings are observed.
Low duty cycle pulses, not DC because of heating.
Limiting values
Parameter
reference voltage (A)
reference voltage (B)
input voltage
voltage on an input/output pin
channel current (DC)
input clamping current
output clamping current
storage temperature
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 30 August 2010
[2]
Conditions
V
I
< 0 V
NVT2001; NVT2002
Bidirectional voltage level translator
Min
−0.5
−0.5
−0.5
−0.5
-
−50
−50
−65
[1]
[1]
© NXP B.V. 2010. All rights reserved.
Max
+6
+6
+6
+6
128
-
+50
+150
Unit
V
V
V
V
mA
mA
mA
°C
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