Datasheet
7
LTC1274/LTC1277
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
Reference Voltage vs
Load Current
LOAD CURRENT (mA)
–6
REFERENCE VOLTAGE (V)
2.435
2.430
2.425
2.420
2.415
2.410
2.405
–3 –1
LT1274/77 • TPC13
–5 –4
–2 0 1
Supply Current vs Temperature
TEMPERATURE (°C)
–55
SUPPLY CURRENT (mA)
3.0
2.5
2.0
1.5
1.0
0.5
0
25 75
LT1274/77 • TPC11
–25 0
50 100 125
f
SAMPLE
= 100kHz
Power Supply Feedthrough vs
Ripple Frequency
RIPPLE FREQUENCY (kHz)
1
AMPLITUDE OF POWER SUPPLY FEEDTHROUGH (dB)
10 100 1000
LTC1274/77 • TPC12
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
f
SAMPLE
= 100kHz
AV
DD
(V
RIPPLE
= 1mV)
V
SS
(V
RIPPLE
= 10mV)
DGND (V
RIPPLE
= 0.1V)
Supply Current vs Sample Rate
With Sleep and Nap Modes
SAMPLE RATE (Hz)
SUPPLY CURRENT (µA)
10000
1000
100
10
1
0.1 1k 100k
LTC1274/77 • TPC15
101 10k100
WITHOUT SLEEP OR NAP
NAP = 5V
(SLEEP MODE)
NAP = REFRDY
(SLEEP MODE)
NAP MODE
C
REF
= 4.7µF
Wake-Up Time vs
C
REF
(Sleep Mode)
Supply Current vs
Supply Voltage
C
REF
(µF)
0
WAKE-UP TIME (ms)
10
9
8
7
6
5
4
3
2
1
0
40
LTC1274/77 • TPC16
10515253545
20
30
50
T
A
= 25°C
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT (mA)
3.0
2.5
2.0
1.5
1.0
0.5
0
1
234
LTC1274/77 • TPC14
56
f
SAMPLE
= 100kHz
PI FU CTIO S
UU U
LTC1274
A
IN
(Pin 1): Analog Input. 0V to 4.096V, unipolar (V
SS
=
0V) or ±2.048V, bipolar (V
SS
= –5V).
V
REF
(Pin 2): 2.42V Reference Output. Bypass to AGND
(10µF tantalum in parallel with 0.1µF ceramic). V
REF
can be
overdriven positive with an external reference voltage.
AGND (Pin 3): Analog Ground.
D11 to D4 (Pins 4 to 11): Three-State Data Outputs. D11
is the Most Significant Bit.
DGND (Pin 12): Digital Ground.
D3 to D0 (Pins 13 to 16): Three-State Data Outputs.
REFRDY (Pin 17): Reference Ready Signal. It goes high
when the reference has settled after SLEEP indicating that
the ADC is ready to sample.
SLEEP (Pin 18): SLEEP Mode Input. Tie this pin to low to
put the ADC in Sleep mode and save power (REFRDY will
go low). The device will draw 1µA in this mode.
CONVST (Pin 19): Conversion Start Signal. This active low
signal starts a conversion on its falling edge (to recognize
CONVST, CS has to be low.)