LTC1041
1
1041fa
■
Micropower 1.5µW (1 Sample/Second)
■
Wide Supply Range 2.8V to 16V
■
High Accuracy
Guaranteed
SET POINT Error ±0.5mV Max
Guaranteed
Deadband ±0.1% of Value Max
■
Wide Input Voltage Range V
+
to Ground
■
TTL Outputs with 5V Supply
■
Two
Independent
Ground-Referred Control Inputs
■
Small Size 8-Pin SO
The LTC
®
1041 is a monolithic CMOS BANG-BANG
controller manufactured using Linear Technology’s
enhanced LTCMOS™ silicon gate process. BANG-BANG
loops are characterized by turning the control element
fully ON or fully OFF to regulate the average value of
the parameter to be controlled. The SET POINT input
determines the average control value and the DELTA input
sets the deadband. The deadband is always 2 x DELTA and
is centered around the SET POINT. Independent control
of the SET POINT and deadband, with no interaction, is
made possible by the unique sampling input structure of
the LTC1041.
An external RC connected to the OSC pin sets the sampling
rate. At the start of each sample, internal power to the
analog section is switched on for ≈ 80µs. During this time,
the analog inputs are sampled and compared. After the
comparison is complete, power is switched off. This
achieves extremely low average power consumption
at low sampling rates. CMOS logic holds the output
continuously while consuming virtually no power.
To keep system power at an absolute minimum, a switched
power output (V
P-P
) is provided. External loads, such as
bridge networks and resistive dividers, can be driven by
this switched output.
The output logic sense (i.e., ON = V
+
) can be reversed
(i.e., ON = GND) by interchanging the V
IN
and SET POINT
inputs. This has no other effect on the operation of
the LTC1041.
BANG-BANG Controller
, LTC and LT are registered trademarks of Linear Technology Corporation.
FEATURES
APPLICATIO S
U
DESCRIPTIO
U
■
Temperature Control (Thermostats)
■
Motor Speed Control
■
Battery Charger
■
Any ON-OFF Control Loop
LTCMOS is a trademark of Linear Technology Corporation.
Ultralow Power 50°F to 100°F (2.4µW) Thermostat
Supply Current vs Sampling Frequency
TYPICAL APPLICATIO
U
1N4002
(4)
0.1µF
26V AC 2-WIRE THERMOSTAT
4.32k
5k
6.81k
49.9Ω
ALL RESISTORS 1%. YELLOW SPRINGS INSTRUMENT CO., INC. P/N 44007.
DRIVING THERMISTOR WITH V
P-P
ELIMINATES 3.8°F ERROR DUE TO SELF-HEATING
4.99k
1µF
6V
+
10M
LTC1041 • TA01
56Ω
I
S
400nA
8
7
6
5
1
2
3
4
DELTA = 0.5°F
2N6660
†
†
LTC1041
SAMPLING FREQUENCY, f
S
(Hz)
0.1
0.01
SUPPLY CURRENT, I
S
(µA)
0.1
1
10
100
1000
10000
1 10 100 1000
LTC1041 • TA02
10000
V
S
= 6V
TOTAL SUPPLY
CURRENT
LTC1041 SUPPLY
CURRENT
