GTL2002_7

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 07 — 2 July 2009

6 of 22

NXP Semiconductors

GTL2002

2-bit bidirectional low voltage translator

8.2 Unidirectional down translation

For unidirectional clamping, higher voltage to lower voltage, the GREF input must be

(typically 200 k

Ω). A filter capacitor on DREF is recommended. Pull-up resistors are

required if the chip set I/O are open-drain. The opposite side of the reference transistor

(SREF) is connected to the processor core supply voltage. When DREF is connected

through a 200 k

Ω resistor to a 3.3 V to 5.5 V V

8.3 Unidirectional up translation

For unidirectional up translation, lower voltage to higher voltage, the reference transistor is

connected the same as for a down translation. A pull-up resistor is required on the higher

voltage side (Dn or Sn) to get the full HIGH level, since the GTL-TVC device will only pass

the reference source (SREF) voltage as a HIGH when doing an up translation. The driver

on the lower voltage side only needs pull-up resistors if it is open-drain.

Typical unidirectional HIGH-to-LOW voltage translation.

Fig 7.

Unidirectional down translation to protect low voltage processor pins

GREF

DREF

002aac061

D1

D2

200 k

Ω

CHIPSET I/O

5 V

GND

SREF

S1

S2

CPU I/O

1.8 V

1.5 V

1.2 V

1.0 V

totem pole I/O

easy migration to lower voltage

as processor geometry shrinks

Typical unidirectional LOW-to-HIGH voltage translation.

Fig 8.

Unidirectional up translation to higher voltage chip sets

GREF

DREF

002aac062

D1

D2

200 k

Ω

CHIPSET I/O

5 V

GND

SREF

S1

S2

CPU I/O

1.8 V

1.5 V

1.2 V

1.0 V

easy migration to lower voltage

as processor geometry shrinks

totem pole I/O

or open-drain