Rainbow Electronics MAX1083 - Manual (Page 14)

MAX1082/MAX1083
300ksps/400ksps, Single-Supply, 4-Channel,
Serial 10-Bit ADCs with Internal Reference
14 ______________________________________________________________________________________
BIT NAME DESCRIPTION
7(MSB) START The first logic “1” bit after CS goes low defines the beginning of the control byte.
6 SEL2 These 3 bits select which of the eight channels are used for the conversion (Tables 1 and 2).
5 SEL1
4
SEL0
3 UNI/BIP 1 = unipolar, 0 = bipolar. Selects unipolar or bipolar conversion mode. In unipolar mode, an
analog input signal from 0 to V
REF can be converted; in bipolar mode, the differential signal can
range from -V REF /2 to +V REF /2.
2 SGL/DIF 1 = single ended, 0 = pseudo-differential. Selects single-ended or pseudo-differential conver-
sions. In single-ended mode, input signal voltages are referred to COM. In pseudo-differential
mode, the voltage difference between two channels is measured (Tables 1 and 2).
1 PD1 Select operating mode.
0(LSB) PD0 PD1 PD0 Mode
0 0 Full power-down
0 1 Fast power-down
1 0 Reduced power
1 1 Normal operation
Table 3. Control-Byte Format
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
(MSB) (LSB)
START SEL2 SEL1 SEL0 UNI/BIP SGL/DIF PD1 PD0
Once conversion is completed, the device goes into
the programmed power mode until a new control byte
is written.
The power-up delay is dependent on the power-down
state. Software low-power modes will be able to start
conversion immediately when running at decreased
clock rates (see Power-Down Sequencing). Upon
power-on reset, when exiting software full power-down
mode, or when exiting hardware shutdown, the device
goes immediately into full-power mode and is ready to
convert after 2µs when using an external reference.
When using the internal reference, wait for the typical
power-up delay from a full power-down (software or
hardware) as shown in Figure 8.
PD1/PD0 MODE
TOTAL SUPPLY CURRENT CIRCUIT SECTIONS*
CONVERTING
(mA)
AFTER
CONVERSION
INPUT COMPARATOR REFERENCE
00
Full Power-Down
(FULLPD)
2.5 2µA Off Off
01
Fast Power-Down
(FASTPD)
2.5 0.9mA Reduced Power On
10
Reduced Power
Mode (REDP)
2.5 1.3mA Reduced Power On
11 Normal Operating 2.5 2.0 mA Full Power On
Table 4. Software-Controlled Power Modes
* Circuit operation between conversions; during conversion all circuits are fully powered up.