Fairchild FSTD3125 service manual

May 2012

FSTD3125 — 4-Bit Bus Switch with Level Shifting

Features

 4Ω Switch Connection between Two Ports  Minimal Propagation Delay through the Switch  Low I

CC

 Zero Bounce in Flow-through Mode  Control Inputs Compatible with TTL Level  TruTranslation Voltage Translation from 5.0V Inputs

to 3.3V Outputs

Ordering Information

Operating

Part Number

FSTD3125MTCX -40 to 85°C

Temperature

Range

14-Lead, Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4mm Wide

Description

Fairchild switch FSTD3125 provides four high-speed CMOS TTL-compatible bus switches. The low on resistance of the switch allows inputs to be connected to outputs without adding propagation delay or generating additional ground bounce noise. A diode to V been integrated into the circuit to allow for level shifting between 5V inputs and 3.3V outputs.

The device is organized as four one-bit switches with separate /OE inputs. When /OE is LOW, the switch is ON and port A is connected to port B. When /OE is HIGH, the switch is OPEN and a high-impedance state exists between the two ports.

Package

Packing

Tape and Reel

has

CC

Method

1

/OE

1

23

1A

4

/OE

2

56

2A

10

/OE

3

9

3A

13

/OE

4

4A

1B

2B

8

3B

1112

4B

Figure 1. Logic Diagram

4

3

Pin Configuration

FSTD3125 — 4-Bit Bus Switch with Level Shifting

Pin Descriptions

1A

1B

2A

2B

1

2

3

4

2

5

6

7

/OE

GND

Figure 2. Pin Assignments

14

13

12

11

10

V

CC

/OE

4A

4B

/OE

3A

9

3B

8

Pin # Pin Names Description

1, 4, 10, 13 /OE1, /OE2, /OE3, /OE4 Bus Switch Enables

2, 5, 9, 12 1A, 2A, 3A, 4A Bus A 3, 6, 8, 11 1B, 2B, 3B, 4B Bus B

14 VCC Supply Voltage

7 GND Ground

Truth Table

Inputs Inputs/Outputs

/OE A, B LOW A = B HIGH High Impedance

FSTD3125 — 4-Bit Bus Switch with Level Shifting

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.

Symbol Parameter Min. Max. Unit

VCC Supply Voltage -0.5 7.0 V

VS DC Switch Voltage -0.5 7.0 V

VIN DC Input Voltage

IIK DC Input Diode Current, VIN<0V -50 mA

I

DC Output Sink Current 128 mA

OUT

ICC / I

DC V

GND

T

Storage Temperature Range -65 +150 °C

STG

/ GND Current ±100 mA

CC

Note:

1. The input and output negative voltage ratings may be exceeded if the input and output diode current ratings are observed.

(1)

-0.5 7.0 V

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol Parameter Min. Max. Unit

VCC Power Supply Operating 4.5 5.5 V

VIN Input Voltage 0 5.5 V

V

Output Voltage 0 5.5 V

OUT

tr, tf Input Rise and Fall Time

Switch Control Input Switch I/O 0 DC

TA Operating Temperature, Free Air -40 +85 °C

Note:

2. Unused control inputs must be held HIGH or LOW. They may not float.

(2)

0 5

ns/V