ST 74VHC238 User Manual

74VHC238

3 TO 8 LINE DECODER

■ HIGH SPEED: t

■ LOW POWER DISSIPATION:

I

= 4 µA (MAX.) at TA=25°C

CC

■ HIGH NOISE IMMUNITY:

V

= V

NIH

■ POWER DOWN PROTECTION ON INPUTS

■ SYMMETRICAL OUTPUT IMPEDANCE:

|I

OH

■ BALANCED PROPAGATION DELAYS:

t

PLH

■ OPERATING VOLTAGE RANGE:

V

CC

■ PIN AND FUNCTION COMPATIBLE WITH

NIL

| = IOL = 8 mA (MIN)

≅ t

PHL

(OPR) = 2V to 5.5V

= 5.5 ns (TYP.) at VCC = 5V

PD

= 28% VCC (MIN.)

74 SERIES 238

■ IMPROVED LATCH-UP IMMUNITY

DESCRIPTION

The 74VHC238 is an advanced high-speed CMOS 3 TO 8 LINE DECODER fabricated with sub-micron silicon gate and double-layer metal wiring C

2

MOS technology. If the device is enabled, 3 binary select inputs (A, B, and C) determine which one of the outputs will go high. If enable in put G1 is held low or either G2A

or G2B is held high, decoding function is

inhibited and all the 8 outputs go to low.

TSSOPSOP

Table 1: Order Codes

PACKAGE T & R

SOP 74VHC238MTR

TSSOP 74VHC238TTR

Tree enable inpu ts are provided to ease cascade connection and application of address decoders for memory systems. Power down protection is provided on all inputs and 0 to 7V can be accepted on inputs with no regard to the supply voltage. This device can be used to interface 5V to 3V. All inputs and outputs are equipped with protection circuits against static disc harge, giving them 2KV ESD immunity and transient excess voltage.

Figure 1: Pin Connection And IEC Logic Symbols

Rev. 4

1/12November 2004

74VHC238

Figure 2: Input Equivalent Circuit Table 2: Pin Description

PIN N° SYMBOL NAME AND FUNCTION

1, 2, 3 A, B, C Address Inputs

4, 5 G2A

6 G1 Enable Input

15, 14, 13,

12, 1 1, 10, 9,

7 8 GND Ground (0V)

16 V

Table 3: Truth Table

, G2B Enable Inputs

Y0 to Y7 Outputs

CC

Positive Supply Voltage

INPUTS

ENABLE SELECT

G2B

X : Don’t ca re

G2A G1 C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7

XXLXXXLLLLLLLL XHXXXXLLLLLLLL HXXXXXLLLLLLLL LLHLLLHLLLLLLL LLHLLHLHLLLLLL LLHLHLLLHLLLLL LLHLHHLLLHLLLL LLHHLLLLLLHLLL LLHHLHLLLLLHLL LLHHHLLLLLLLHL LLHHHHLLLLLLLH

OUTPUTS

Figure 3: Logic Diagram

This logi c di agram has not be used to est i m ate propaga tion delays

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74VHC238

Table 4: Absolute Maximum Ratings

Symbol Parameter Value Unit

V

I

OK

I

or I

I

CC

T

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied

Table 5: Recommended Operating Conditions

Symbol Parameter Value Unit

V

V V T

dt/dv

Supply Voltage

CC

DC Input Voltage

I

DC Output Voltage -0.5 to VCC + 0.5

O

DC Input Diode Current

IK

DC Output Diode Current DC Output Current

O

DC VCC or Ground Current

GND

Storage Temperature

stg

Lead Temperature (10 sec)

L

Supply Voltage

CC

Input Voltage

I

Output Voltage 0 to V

O

Operating Temperature

op

Input Rise and Fall Time (note 1) (V (V

= 3.3 ± 0.3V)

CC

= 5.0 ± 0.5V)

CC

-0.5 to +7.0 V

- 20 mA

± 20 mA ± 25 mA ± 75 mA

-65 to +150 °C 300 °C

2 to 5.5 V 0 to 5.5 V

CC

-55 to 125 °C 0 to 100

0 to 20

ns/V

V

1) VIN from 30 % t o 70% of V

CC

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74VHC238

Table 6: DC Specifications

Symbol Parameter

V

High Level Input

IH

Voltage

V

Low Level Input

IL

Voltage

High Level Output

OH

Voltage

Low Level Output

OL

Voltage

I

Input Leakage

I

Current

I

Quiescent Supply

CC

Current

3.0 to

Test Condition Value

V

(V)

CC

T

A

Min. Typ. Max. Min. Max. Min. Max.

-40 to 85°C -55 to 125°C

= 25°C

2.0 1.5 1.5 1.5

5.5

0.7V

CC

0.7V

CC

0.7V

CC

2.0 0.5 0.5 0.5

5.5

2.0

3.0

4.5

3.0

4.5

2.0

3.0

4.5

3.0

4.5

0 to

VI = 5.5V or GND

5.5 V

5.5

IO=-50 µA I

=-50 µA

O

=-50 µA

I

O

=-4 mA

I

O

=-8 mA

I

O

IO=50 µA

=50 µA

I

O

=50 µA

I

O

=4 mA

I

O

=8 mA

I

O

= VCC or GND

I

0.3V

CC

1.9 2.0 1.9 1.9

2.9 3.0 2.9 2.9

4.4 4.5 4.4 4.4

2.58 2.48 2.4

3.94 3.8 3.7

0.0 0.1 0.1 0.1

0.36 0.44 0.55

± 0.1 ± 1 ± 1 µA

44040µA

0.3V

CC

0.3V

CC

Unit

V

Table 7: AC Electrical Characteristics (Input t

Test Condition Value

Symbol Parameter

t

Propagation Delay

PLH

t

t t

(*) Voltage range is 3.3V ± 0.3V (**) Volt age range is 5.0V ±

Time

PHL

A, B, C, to Y

Propagation Delay

PLH

Time

PHL

G1 to Y

Propagation Delay

PLH

Time

PHL

G2A

, G2B to Y

0.5V

V

3.3

5.0

3.3

5.0

3.3

5.0

C

CC

(V)

L

(pF)

(*)

15 8.0 12.3 1.0 14.5 1.0 14.5

(*)

50 10.5 15.8 1.0 18.0 1.0 18.0

(**)

15 5.5 8.1 1.0 9.5 1.0 9.5

(**)

50 7.0 10.1 1.0 11.5 1.0 11.5

(*)

15 8.1 12.8 1.0 15.0 1.0 15.0

(*)

50 10.6 16.3 1.0 18.5 1.0 18.5

(**)

15 5.4 8.1 1.0 9.5 1.0 9.5

(**)

50 6.9 10.1 1.0 11.5 1.0 11.5

(*)

15 8.1 12.3 1.0 14.5 1.0 14.5

(*)

50 10.6 15.8 1.0 18.0 1.0 18.0

(**)

15 5.7 8.1 1.0 9.5 1.0 9.5

(**)

50 7.2 10.1 1.0 11.5 1.0 11.5

= tf = 3ns)

r

= 25°C

T

A

-40 to 85°C -55 to 125°C

Min. Typ. Max. Min. Max. Min. Max.

Unit

ns

4/12