AD7858 Analog Devices, AD7858 Datasheet - Page 5

• Manufacturer Part Number: AD7858
• Description: 3 V to 5 V Single Supply, 200 kSPS, 8-Channel, 12-Bit, Serial Sampling ADC
• Manufacturer: Analog Devices

Specifications of AD7858

• Resolution (bits): 12bit
• # Chan: 8
• Sample Rate: 200kSPS
• Interface: Ser,SPI
• Analog Input Type: SE-Uni
• Ain Range: (Vref) p-p,Uni (Vref)
• Adc Architecture: SAR
• Pkg Type: DIP,SOIC

TYPICAL TIMING DIAGRAMS
Figures 2 and 3 show typical read and write timing diagrams for
serial Interface Mode 2. The reading and writing occurs after
conversion in Figure 2, and during conversion in Figure 3. To
attain the maximum sample rate of 100 kHz (AD7858L) or
200 kHz (AD7858), reading and writing must be performed
during conversion as in Figure 3. At least 400 ns acquisition
time must be allowed (the time from the falling edge of BUSY
to the next rising edge of CONVST) before the next conversion
begins to ensure that the part is settled to the 12-bit level. If the
user does not want to provide the CONVST signal, the conver-
sion can be initiated in software by writing to the control register.
CONVST (I/P)
CONVST (I/P)
DOUT (O/P)
BUSY (O/P)
DOUT (O/P)
BUSY (O/P)
SYNC (I/P)
SCLK (I/P)
SYNC (I/P)
SCLK (I/P)
DIN (I/P)
DIN (I/P)
t
t
2
2
t
t
1
1
THREE-STATE
t
CONVERT
THREE-STATE
t
t
1
1
t
t
= 100ns MIN,
4
= 100ns MIN,
4
t
t
CONVERT
CONVERT
t
t
3
3
DB15
DB15
t
t
7
7
1
1
t
DB15
= 4.6 s MAX, 10 s MAX FOR L VERSION
t
DB15
= 4.6 s MAX, 10 s MAX FOR L VERSION
4
4
t
t
= 50/90ns MAX 5V/3V,
= 50/90ns MAX 5V/3V,
6
6
t
t
t
8
CONVERT
8
DB11
DB11
5
5
DB11
DB11
OUTPUT
t
t
t
6
t
t
6
t
9
7
9
7
= 40/60ns MIN 5V/3V
= 40/60ns MIN 5V/3V
PIN
TO
t
t
6
6
10
10
100pF
DB0
DB0
C
16
L
16
200 A
1.6mA
DB0
DB0
t
t
11
11
t
t
12
12
AD7858/AD7858L
THREE-
THREE-
STATE
STATE
I
I
OH
OL
+2.1V