GTL2010 Datasheet, PDF (7/20 Pages) NXP Semiconductors – 10-bit GTL Processor Voltage Clamp

NXP Semiconductors
GTL2010
10-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---^l--_0t--^a-_.-₀--^g-₁--^e-₅----⁽--_AV-----⁾---^–-------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, “Bi-directional low
voltage translators” for more information.
Table 6. Pull-up resistor values
Voltage
Pull-up resistor value (Ω)^[1]
15 mA^[2]
10 mA^[2]
3 mA^[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
[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_CC range and resistor tolerance.
GTL2010_6
Product data sheet
Rev. 06 — 3 March 2008
© NXP B.V. 2008. All rights reserved.
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