AS1538-BTST austriamicrosystems, AS1538-BTST Datasheet - Page 14

• Manufacturer Part Number: AS1538-BTST
• Description: IC ADC 12BIT 8CH 50K 16-TSSOP
• Manufacturer: austriamicrosystems

Specifications of AS1538-BTST

• Number Of Bits: 12
• Sampling Rate (per Second): 50k
• Data Interface: I²C, Serial
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AS1538/AS1540
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
Initiating a Conversion
After the AS1538/AS1540 has been write-addressed by the bus master, the A/D converter circuitry is powered on, and
conversions will begin when a command byte bit C0
is valid, the AS1538/AS1540 will return an ACK.
Reading Data
Data can be read from the AS1538/AS1540 by read-addressing the device (LSB of address byte set to 1
mand Byte on page
AS1540 once a conversion has been initiated as described in
Each 12-bit data word
LSB. Byte 0 is sent first, followed by Byte 1.
Figure 27. Data Word
Figure 28
The most efficient way to perform continuous conversions is to issue repeated STARTs to the AS1538/AS1540 (to
secure the bus for subsequent ADC conversions) after reading each conversion. It is recommended that during the
conversion mode no data is clocked into the ADC to prevent internal noise. Therefore, after the repeated start com-
mend it is recommanded not to clock in or out any data from the converter for 3.7µs. The ADC powers up after the PD0
bit is clocked in and it takes 1.4µs to fully power up. At a clock frequency of 3.4MHz this time is automatically achieved
and no extra delay should be included.
Figure 28. Read Sequence
Where:
A: Acknowledge (SDA Low)
N: Not Acknowledge (SDA High)
S: START Condition
P: STOP Condition
Sr: Repeated START Condition
W: 0 (Write)
R: 1 (Read)
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ADC Conversion Mode
Sr
3.7µs
illustrates the interaction between the master and the slave AS1538/AS1540.
S
1
1
From Master to Slave
From Slave to Master
0
0
12)) and receiving the transmitted bytes. Converted data can only be read from the AS1538/
Read-Addressing Byte
Write-Addressing Byte
(see Figure 27)
0
0
Byte 0
Byte 1
1
1
ADC Powerdown Mode
0
0
MSB
D7
0
A1 A0
A1 A0
is returned in two bytes, where D11 is the MSB of the data word, and D0 is the
* Dependant on powerdown selection bits PD0 and PD1
D6
6
0
W
R
A
A
D5
5
0
SD C2 C1 C0 PD1 PD0 X
0
(see Command Byte on page 12)
Revision 1.03
0
ADC Powerdown Mode *
D4
4
0
0
Command Byte
Initiating a
0
D11
D3
3
D11 D10 D9 D8
ADC Sampling Mode
Conversion.
D10
D2
2
X
D9
D1
1
A
A
is received. If the address byte
D7
Use repeated STARTs to secure the
bus operation and loop back to the
stage of write-addressing for the
next conversion.
LSB
D8
D0
D6 ... D1
D0
N
(see Com-
P
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