GTL2002_7

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 07 — 2 July 2009

7 of 22

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]

[2]

[3]

Table 6.

Pull-up resistor values

Pull-up resistor value (

Ω)[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

Ω

()

pull-up voltage V

() 0.35 V

–

0.015 A

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