DS1802E Maxim Integrated Products, DS1802E Datasheet - Page 10

• Manufacturer Part Number: DS1802E
• Description: IC POT DL AUDIO TAP W/PB 20TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of DS1802E

• Taps: 64
• Resistance (ohms): 45K
• Number Of Circuits: 2
• Temperature Coefficient: 750 ppm/°C Typical
• Memory Type: Volatile
• Interface: 3-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Resistance In Ohms: 45K
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

CASCADE OPERATION
A feature of the DS1802 is the ability to control multiple devices from a single processor. Multiple
DS1802s can be linked or daisy-chained as shown in Figure 7. As a bit is entered in to the I/O shift
registeroftheDS1802 it will appear at the C
The C
multiple devices, the total number of bits sent is always 16 times the number of DS1802s in the daisy
chain.
An optional feedback resistor can be placed between the C
of the first DS1802, thus allowing the controlling processor to circularly clock data through the daisy
chain. The value of the feedback or isolation resistor should be in the range from 2 k
When reading data via the C
When
the isolation resistor. When the CLK input transitions low to high, bit 0 is loaded into the first position of
the I/O shift register and bit 1 becomes present on C
times the number of DS1802s in the daisy chain), the data has shifted completely around and back to its
original position. When
the read occurred) is loaded into the wiper-0 and wiper-1.
CASCADING MULTIPLE DEVICES Figure 7
Zero-Crossing Detection
The DS1802 provides a zero-crossing detection capability when using the 3-Wire Serial interface. Zero-
crossing detection provides a means for minimizing any audible noise that may result from sizable
discrete wiper transitions when using the part in audio applications. The zero-crossing detect feature
allows independent wiper changes only when the two terminals of the potentiometer have equal potentials
and within a 50 ms time window from the fall of the
a zero-crossing, the wiper position of the potentiometer(s) will change regardless of the state of the input
signal. Zero-crossing detection is activated when the
Zero-crossing detection is also available when using the part in pushbutton operation. When a pushbutton
is activated, the part will change wiper position during the first detected zero-crossing or at the end of a
50 ms time window.
When operating in pushbutton operation with a continuous input pulse, the wiper position will change
once during the initial 1-second time period. This change is dictated by a detected zero-crossing or 50 ms
ZCEN
OUT
input deactivates both the 50 ms time requirement and zero-crossing detection.
RST
output of the DS1802 can be used to drive the D input of another DS1802. When connecting
is driven high, bit 0 is present on the C
RST
OUT
transitions to the low state to end data transfer, the value (the same as before
pin and isolation resistor, the D line is left floating by the reading device.
OUT
out put after a maximum delay of 50 nanoseconds.
10 of 17
OUT
OUT
RST
ZCEN
pin, which is fed back to the input D pin through
signal. If at 50 ms the DS1802 has not detected
and D of the next device. After 16 bits (or 16
OUT
input level is in a low state. When high, the
terminal of the last device and the D input
to 10 k .
DS1802