GTL2002 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 8 — 19 August 2013 7 of 27
NXP Semiconductors
GTL2002
2-bit bidirectional low voltage translator
8.4 Sizing pull-up resistor
The pull-up resistor value needs to limit the current through the pass transistor when it is
in the ON state to about 15 mA. This will guarantee a pass voltage of 260 mV to 350 mV.
If the current through the pass transistor is higher than 15 mA, the pass voltage will also
be higher in the ON state. To set the current through each pass transistor at 15 mA, the
pull-up resistor value is calculated as shown in Equation 1
:
(1)
Table 6
summarizes resistor values for various reference voltages and currents at 15 mA
and also at 10 mA and 3 mA. The resistor value shown in the +10 % column or a larger
value should be used to ensure that the pass voltage of the transistor would be 350 mV or
less. The external driver must be able to sink the total current from the resistors on both
sides of the GTL-TVC device at 0.175 V, although the 15 mA only applies to current
flowing through the GTL-TVC device. See application note AN10145, “Bidirectional low
voltage translators” for more information.
[1] Calculated for V
OL
=0.35V.
[2] Assumes output driver V
OL
= 0.175 V at stated current.
[3] + 10 % to compensate for V
DD
range and resistor tolerance.
Table 6. Pull-up resistor values
Pull-up resistor value ()
[1]
Voltage 15 mA
[2]
10 mA
[2]
3mA
[2]
Nominal +10%
[3]
Nominal +10%
[3]
Nominal +10%
[3]
5.0 V 310 341 465 512 1550 1705
3.3 V 197 217 295 325 983 1082
2.5 V 143 158 215 237 717 788
1.8 V 97 106 145 160 483 532
1.5 V 77 85 115 127 383 422
1.2 V 57 63 85 94 283 312
resistor value
pull-up voltage V 0.35 V–
0.015 A
--------------------------------------------------------------------------
=
