ISD2548E Просмотр технического описания (PDF) - Information Storage Devices

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ISD2548E

Single-Chip Voice Record/Playback Devices 32-*, 40-*, 48-*, 64-*, 60-, 75-, 90-, and 120-Second Durations

Information Storage Devices 

ISD2500 Series

Product Data Sheets

specification. The frequency is then maintained to

a variation of ±2.25% over the entire commercial

temperature and operating voltage ranges. The

internal clock has a ±5% tolerance over the indus-

trial temperature and voltage range. A regulated

power supply is recommended for industrial tem-

perature range parts. If greater precision is

required, the device can be clocked through the

XCLK pin as follows:

Part

Number

ISD2560

ISD2575

ISD2590

-1 ISD25120

ISD2532*

ISD2540*

ISD2548*

ISD2564*

Sample Rate Required Clock

8.0 KHz

6.4 KHz

5.3 KHz

4.0 KHz

8.0 KHz

6.4 KHz

5.3 KHz

4.0 KHz

1024 KHz

819.2 KHz

682.7 KHz

512 KHz

1024 KHz

819.2 KHz

682.7 KHz

512 KHz

These recommended clock rates should not be

varied because the antialiasing and smoothing fil-

ters are fixed, and aliasing problems can occur if

the sample rate differs from the one recom-

mended. The duty cycle on the input clock is not

critical, as the clock is immediately divided by two.

IF THE XCLK IS NOT USED, THIS INPUT MUST BE CON-

NECTED TO GROUND.

Speaker Outputs (SP+/SP-)

All devices in the ISD2500 Series include an on-

chip differential speaker driver, capable of driving

50 milliwatts into 16 Ω from AUX IN (12.2 mW from

memory).

The speaker outputs are held at VSSA levels during

record and power down. It is therefore not possible

to parallel speaker outputs of multiple ISD2500

devices or the outputs of other speaker drivers.

NOTE

Connection of speaker outputs in parallel

may cause damage to the device.

A single output may be used alone (including a

coupling capacitor between the SP pin and the

speaker). These outputs may be used individually

with the output signal taken from either pin. Using

the differential outputs results in a 4:1 improve-

ment in output power.

NOTE

Never ground or drive an unused speaker

output.

Auxiliary Input (AUX IN)

The Auxiliary Input is multiplexed through to the

output amplifier and speaker output pins when CE

is HIGH, P/R is HIGH, and Playback is currently

not active or if the device is in Playback overflow.

When cascading multiple ISD2500 devices, the

AUX IN pin is used to connect a Playback signal

from a following device to the previous output

speaker drivers. For noise considerations, it is sug-

gested that the auxiliary input not be driven when

the storage array is active.

Address/Mode Inputs (Ax/Mx)

The Address/Mode Inputs have two functions

depending on the level of the two Most Significant

Bits (MSB) of the address (A8 and A9 for the

ISD256075/90/120 devices, and A7 and A8 for the

ISD2532/40/48/64* devices).

If either or both of the two MSBs are LOW, the

inputs are ALL interpreted as address bits and are

used as the start address for the current Record or

Playback cycle. The address pins are inputs only

and do not output internal address information as

the operation progresses. Address inputs are

latched by the falling edge of CE.

If both MSBs are HIGH, the Address/Mode Inputs

are interpreted as Mode bits according to the

Operational Mode table on page 1-85. There are

six operational modes (M0..M6) available as indi-

1–84

* Advance information: ISD2532/40/48/64 devices.

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