ls7210 LSI Computer Systems, Inc., ls7210 Datasheet

ls7210

Manufacturer Part Number

ls7210

Description

Programmable Digital Delay Timer

Manufacturer

LSI Computer Systems, Inc.

Datasheet

1.LS7210.pdf (4 pages)

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LS7210

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7210-061606-1

FEATURES:

• Programmable Delay from 6ms to "Infinity"

• Can be Cascaded for Sequential Events or Extended Delay

• +4.75V to +15V Operation (Vss - V

• On Chip Oscillator or External Clock time base

• High Noise Immunity

• LS7210 (DIP); LS7210-S (SOIC) - (See Figure 1)

DESCRIPTION:

The LS7210 is a MOS programmable digital timer that can generate

a delay in the range of 6ms to infinity. The delay is programmed by 5

binary weighted input bits in combination with the time base pro-

vided. The chip can be operated in four different modes: Delayed

Operate, Delayed Release, Dual Delay and One Shot. These modes

are selected by the control inputs A and B.

INPUT/OUTPUT DESCRIPTION:

OSCILLATOR Input (Pin 5)

The frequency of the internal oscillator is set by an RC network con-

nected to the OSC input, as shown in Figure 2. The nominal os-

cillator frequency, f, at room temperature is given by f

R values range from a minimum of 47K to a maximum 3M .

NOTE: Oscillation accuracy from chip to chip for a fixed value of RC,

is + 10%. (Parts can supplied to tighter tolerances.)

EXTERNAL CLOCK Input (Pin 6)

If the internal oscillator is not used, the chip can be driven by an ex-

ternal clock applied to this input.

CLOCK SELECT Input (Pin 4)

The internal oscillator or the external clock is selected by the proper

logic level applied to this input. A logic 1 selects the external clock

and logic 0 selects the internal oscillator. (See Note 1)

TRIGGER Input (Pin 3)

A positive or a negative transition at the trigger input initiates a delay

in turning on or off the output. A negative transition always turns on

the output with or without delay depending on the selected mode. A

positive transition at the trigger input always turns off the output (with

the exception of one-shot mode) with or without delay depending on

the selected mode. The delay is a function of the time base fre-

quency and the weighting factor programmed at the weighting bit in-

puts. The trigger input is clocked into the input latch with the neg-

ative edge of the selected time base clock. All timings begin after the

latch has been set up. (See Note 1)

WEIGHTING FACTOR Inputs, WB0-WB4 (Pins 12-8)

A delay from the trigger input to the output is programmed by ap-

plying 1's complement binary weighted numbers at these 5 inputs.

(See Note 1) The exact equation for the delay is:

Delay = (1 + 1, 023N)

U L

A3800

LSI/CSI

LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747

PROGRAMMABLE DIGITAL DELAY TIMER

N = Weighting Factor

f = Oscillation Frequency

)

1/RC where

Example: For a weighting factor of 25, inputs WB4, WB3, and

WB0 should be programmed to logic 0.

MODE SELECT Inputs A, B (Pins 2, 1)

The chip can be programmed to operate in four different modes

by applying the logic levels to inputs A and B as indicated in

Table 2. The mode select inputs are clocked into the input latch-

es with the negative edge of the time base clock. These inputs

should not be changed while a delay timing is in progress.

(See Note 1)

OUT Output (Pin 13)

The output is an open drain FET. To obtain proper switching of

the output between Logic 0 and 1 levels, an external pull down re-

sistor to V

source, no such pull down is needed. The output is logically in-

verted with respect to the trigger input.

Supply voltage positive, negative terminals.

NOTE 1: These inputs have internal pullup resistors.

EXTERNAL CLOCK

, V

CLOCK SELECT

OSCILLATOR

TABLE 1. WEIGHTING BITS ASSIGNMENTS

CONTROL

(Pins 14, 9)

TRIGGER

INPUTS

must be used. If the output is used only as a current

WB0

WB1

WB2

WB3

WB4

TABLE 2. MODE SELECTION

(-V)

PIN ASSIGNMENT - TOP VIEW

(631) 271-0400 FAX (631) 271-0405

LS7210

FIGURE 1

VALUE

MODE

Dual Delay

Delayed Release

Delayed Operate

One Shot

OUT

WB0

WB1

WB2

WB3

WB4

June 2006

(+V)

Related parts for ls7210

ls7210 Summary of contents

Page 1

... High Noise Immunity • LS7210 (DIP); LS7210-S (SOIC) - (See Figure 1) DESCRIPTION: The LS7210 is a MOS programmable digital timer that can generate a delay in the range of 6ms to infinity. The delay is programmed by 5 binary weighted input bits in combination with the time base pro- vided ...

Page 2

MODE DEFINITION TIMING DIAGRAM: (See Figure 3) DUAL DELAY MODE Thls is the Default Mode when the inputs A and B are left un- programmed. The function of the Dual Delay mode is to provide a time delay on both ...

Page 3

... D - Output remains off in Delayed Operate mode due to positive trigger transition before the turn-on delay is over One-Shot period extended by re-triggering. Note: is the programmed delay. DELAYED RELEASE MODE PROGRAMMED TURN-OFF DELAY FIGURE 4. LS7210 TIMING DIAGRAM (C) (D) (A) (B) ONE-SHOT MODE < ...

Page 4

... Inputs Dual-Delay mode. For symmetical flasher tie Pins 8, 9, 10, 11 and 12 to fixed logic level. NOTE: 7210-061606-4 CLOCK SELECT LOGIC PRESCALER ÷ 1023 (SEE NOTE) POR GENERATOR FIGURE 5. LS7210 BLOCK DIAGRAM NOTE: ÷ 1023 is standard. Any number from 1 to 1022 can be mask programmed. FIGURE 6. ASYMMETRICAL FLASHER OUT 12 WB0 ...

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