AS1542-BTSU ams, AS1542-BTSU Datasheet - Page 23

• Manufacturer Part Number: AS1542-BTSU
• Description: Analog to Digital Converters - ADC
• Manufacturer: ams

Specifications of AS1542-BTSU

• Rohs: yes
• Number Of Channels: 16/8
• Architecture: SAR
• Conversion Rate: 1 MSPs
• Resolution: 12 bit
• Input Type: Single-Ended/Differential
• Snr: 71 dB
• Interface Type: QSPI, SPI
• Operating Supply Voltage: 2.7 V to 5.25 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-28
• Maximum Power Dissipation: 18.4 mW
• Minimum Operating Temperature: - 40 C
• Number Of Converters: 1

AS1542
Data Sheet - D e t a i l e d D e s c r i p t i o n
Auto Shutdown (PM1 = 0, PM0 = X)
In this mode, the AS1542 automatically enters shutdown after the 14th SLK falling edge of each conversion is updated.
When the device is in shutdown mode, the track/hold circuitry is in hold mode.
Note: The control register maintains its data while in shutdown mode.
Figure 34
down until the next CSN falling edge it receives. On this CSN falling edge, the track and hold that was in hold while the
device was in shutdown will return to track.
Note: Wake-up time from auto shutdown is 1µs.
Figure 34. Auto Shutdown Mode Operation
Notes:
1. Control register data is loaded on the 1st 13 SCLK cycles.
2. Set control register bits PM1 = 1 and PM0 = 1 to keep the device in normal mode.
When running the AS1542 with a 20MHz clock, one dummy cycle of 1µs
aquisation time) should be sufficient to ensure the part is fully powered up.
This dummy cycle effectively halves the throughput rate, with every other conversion result being valid. In this mode,
the power consumption of the part is greatly reduced with the part entering shutdown at the end of each conversion.
Note: The end of shutdown can be controlled by the CSN signal.
Power vs. Throughput Rate
By operating the AS1542 in auto shutdown
lower throughput rates. The Power vs. Throughput Rate graph in the Typical Operating Characteristics section shows
how as the throughput rate is reduced, the part remains in its shutdown state longer and the average power consump-
tion over time drops accordingly.
If the AS1542 is operated in a continuous sampling mode with a throughput rate of 100ksps and a SCLK of 20 MHz
(V
sumption is calculated as follows:
The maximum power dissipation during normal operation is 18.4mW (V
shutdown is one dummy cycle (i.e., 1µs) and the remaining conversion time is another cycle (i.e., 1µs) then the
AS1542 will dissipate approximately 18.4mW for 2µs during each conversion cycle. For the remainder of the conver-
sion cycle (8µs), the device remains in shutdown mode. The AS1542 will dissipate approximately 2.5µW for the
remaining 8µs of the conversion cycle. If the throughput rate is 100ksps, the cycle time is 10µs and the average power
dissipated during each cycle is:
www.austriamicrosystems.com
DD
DOUT
SCLK
CSN
= 5V), with bit
DIN
shows the operation of the AS1542 when it is in automatic shutdown mode The AS1542 remains in shut-
shutdown on 14th SCLK
Device enters automatic
falling edge as PM1 = 0
1
Channel ID Bits + Conversion Results
Data into Control/Shadow Register
PM1 (page 14)
((2/10) x 18.4mW) + ((8/10) x 2.5µW) = 3.682mW
= 0, i.e., the device is in auto shutdown mode
14 16
(see page 23)
and remains powered-up
Device begins to power
up on falling CSN edge
on PM1=1 and PM0=1
1
Data into Control/Shadow Register
Revision 1.00
Dummy Conversion
Invalid Data
the average power consumption of the ADC decreases at
14 16
DD
(see Figure 34)
= 5.25V). If the power-up time from auto
Device is fully
powered up
Channel ID Bits + Conversion Results
1
Data into Control/Shadow Register
(see page
Valid Conversion
(16 SCLKs plus Track&Hold
on the 14th SCLK falling
Device enters shutdown
23), then the power con-
edge as PM1 = 0
14 16
23 - 29
(EQ 1)