Rainbow Electronics DS1800 - Manual

E Copyright 1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
patents and other intellectual property rights, please refer to
Dallas Semiconductor data books.
DS1800
Dual Inverting Log Gain/Attenuator
DS1800
PRODUCT PREVIEW
072095 1/13
FEATURES
•
Ultra–low power consumption
•
Operates from 3V or 5V supplies
•
Two digitally controlled, 128–position potentiometers
including mute
•
Logarithmic Gain Characteristics
•
Zero–crossing detection circuitry eliminates noise
caused by discrete wiper position changes
•
Two Control Interfaces
– 3–wire serial CPU control
– Push–button control
•
20–pin DIP (300 Mil), 20–pin SOIC (300 Mil), and
20–pin (173 Mil) TSSOP packaging available
•
Operating Temperature:
– Commercial: 0 ° C to 70 ° C
– Industrial: –40 ° C to 85 ° C
•
Software and hardware mute
•
Resistance Available: 53K Ω
PIN ASSIGNMENT
V CC
P1G
P1A
P0G
P0A
MUTE
AGND
IN1
OUT1
W1
GND
C OUT
CLK
D
RST
ZCEN
MODE
W0
OUT0
IN0
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
20–PIN DIP (300 MIL)
20–PIN SOIC (300 MIL)
20–PIN TSSOP
PIN DESCRIPTION
OUT0,OUT1 – Low–end of resistor
IN0, IN1 – High–end of resistor
W0,W1 – Wiper Terminal
V
CC
– 3V or 5V Power Supply Input
RST – Serial Port Reset Input
CLK – Serial Port Clock Input
D – Serial Port Data Input
C
OUT
– Cascade Data Output
P0G,P1G – Gain Input Pot Controls
P0A,P1A – Attenuation Input Pot Controls
ZCEN – Zero–Crossing Detect Input
MUTE – Hardware Mute Control Input
AGND – Analog Ground
GND – Ground
DESCRIPTION
The DS1800 is a dual audio–taper potentiometer
designed specifically for use in the feedback path of the
inverting configuration of an operational amplifier (see
Figure 2). In this configuration, the DS1800 provides a
V
O
/V
I
relationship of –20log(R
F
/R
I
) giving a gain/attenu-
ation range covering +20 dB to –63 dB. Each poten-
tiometer has a total of 129 positions including mute. The
DS1800 provides five areas of resolution which include
0.25 dB per step from +20 dB to +3 dB, 0.5 dB per step
from +3 dB to –12 dB, 1 dB from –12 dB to –27 dB, and
from –27 dB to –47 dB; 2 dB per step, and from –47 dB to
–63 dB; 4 dB per step. The mute position provides 100
dB of attenuation.
The DS1800 has two control interfaces (see Figure 1).
The first is a 3–wire serial CPU interface consisting of
RST, CLK, and D. The second interface is a contact–
closure interface, allowing easy push–button control
without the need for external debounce or timing cir-
cuitry. The device also provides for software muting (via