Datasheet

LTC6992-1/LTC6992-2/
LTC6992-3/LTC6992-4
25
69921234fc
Typical applicaTions
Changing Between Two Frequencies
6992 TA05
LTC6992-X
MOD
GND
SET
OUT
V
+
DIV
R1
0.1µF 0.1µF
R2
R
SET
V
+
NOTES
WHILE THIS CIRCUIT IS SIMPLER THAN THE CIRCUIT TO THE RIGHT,
ITS FREQUENCY ACCURACY IS WORSE DUE TO THE EFFECT OF
V
+
SUPPLY VARIATION FROM SYSTEM TO SYSTEM AND OVER TEMPERATURE.
NOTES
1. WHEN THE NMOSFET IS OFF, THE FREQUENCY IS SET BY R
SET
= R
SET1
.
2. WHEN THE NMOSFET IS ON, THE FREQUENCY IS SET BY R
SET
= R
SET1
|| R
SET2
.
3. V
+
SUPPLY VARIATION IS NOT A FACTOR AS THE SWITCHING RESISTOR IS
EITHER FLOATING OR CONNECTED TO GROUND.
R
VCO
V
+
‘HC04
f
MAX
f
MIN
ANALOG PWM
DUTY CYCLE CONTROL
(0V TO 1V)
LTC6992-X
MOD
GND
SET
OUT
V
+
DIV
R1
R2
R
SET1
R
SET2
V
+
ANALOG PWM
DUTY CYCLE CONTROL
(0V TO 1V)
V
+
‘HC04
2N7002
f
MIN
f
MAX
Simple Diode Temperature Sensor
6992 TA06
LTC6992-2
MOD
GND
SET
OUT
V
+
DIV
R4
1000k
MOC207M
Q1
OUTPUT
D3
C1
1µF
R5
186k
5V
5V
0.1µF
0.1µF
5V
LT6003
+10mV/C
5V
R1
130k
R2
50k
R3
130k
ADJUST FOR 50% DUTY CYCLE AT 25°C
+
–
R7
16.9k
R8
84.5k
R6
45.3k
D1
1N458
R11
422Ω
N
DIV
= 16
f = 10kHz
PWM OUTPUT FOR ISOLATED MEASUREMENT
+1% DUTY CYCLE CHANGE PER DEGREE C
–10°C TO 65°C RANGE WITH OPTO-ISOLATOR (DC: 15% TO 95%)
R9
365Ω
0.1µF