LTC1041_09 Datasheet, PDF (1/8 Pages) Linear Technology – BANG-BANG Controller

FEATURES
s _{Micropower 1.5µW (1 Sample/Second)}
s _{Wide Supply Range 2.8V to 16V}
s _{High Accuracy}
Guaranteed SET POINT Error ±0.5mV Max
Guaranteed Deadband ±0.1% of Value Max
s _{Wide Input Voltage Range V}⁺ _{to Ground}
s _{TTL Outputs with 5V Supply}
s _{Two Independent Ground-Referred Control Inputs}
s _{Small Size 8-Pin SO}
U
APPLICATIO S
s _{Temperature Control (Thermostats)}
s _{Motor Speed Control}
s _{Battery Charger}
s _{Any ON-OFF Control Loop}
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTCMOS is a trademark of Linear Technology Corporation.
LTC1041
BANG-BANG Controller
DESCRIPTIO
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.
TYPICAL APPLICATIO
Ultralow Power 50°F to 100°F (2.4µW) Thermostat
26V AC 2-WIRE THERMOSTAT
0.1µF
56Ω
2N6660
†
1N4002
(4)
4.32k
5k
6.81k
49.9Ω
4.99k
1
2
3
4
8
7
LTC1041
6
5
DELTA = 0.5°F
10M _IS
400nA
+
6V
1µF
ALL RESISTORS 1%. ^† YELLOW SPRINGS INSTRUMENT CO., INC. P/N 44007. ^{LTC1041 • TA01}
DRIVING THERMISTOR WITH V_P-P ELIMINATES 3.8°F ERROR DUE TO SELF-HEATING
Supply Current vs Sampling Frequency
10000
V_S = 6V
1000
100
TOTAL SUPPLY
CURRENT
10
1
LTC1041 SUPPLY
CURRENT
0.1
0.01
0.1
1
10
100 1000 10000
SAMPLING FREQUENCY, f_S (Hz) LTC1041 • TA02
1041fa
1