GTL2002 Datasheet, PDF (7/22 Pages) NXP Semiconductors – 2-bit bi-directional low voltage translator

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:
resistor value (Ω) = -^p---^u----^l--^l--^---^u---^p------^v---^o---_0l--^t-_.-^a0---₁-^g--₅-^e-----⁽_A--^V-----⁾---^–-----⁰---^.-³---⁵------^V--
(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.
Table 6.
Voltage
5.0 V
3.3 V
2.5 V
1.8 V
1.5 V
1.2 V
Pull-up resistor values
Pull-up resistor value (Ω)^[1]
15 mA^[2]
10 mA^[2]
Nominal + 10 %^[3] Nominal + 10 %^[3]
310
341
465
512
197
217
295
325
143
158
215
237
97
106
145
160
77
85
115
127
57
63
85
94
3 mA^[2]
Nominal + 10 %^[3]
1550
1705
983
1082
717
788
483
532
383
422
283
312
[1] Calculated for V_OL = 0.35 V.
[2] Assumes output driver V_OL = 0.175 V at stated current.
[3] + 10 % to compensate for V_DD range and resistor tolerance.
GTL2002_7
Product data sheet
Rev. 07 — 2 July 2009
© NXP B.V. 2009. All rights reserved.
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