LT1105C View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LT1105C' PDF : 32 Pages View PDF
TYPICAL APPLICATIONS
Setting Oscillator Frequency
LT1103/LT1105
OSC
COSC
LT1103 TA05
CHOOSE 20kHz ≤ fOSC ≤ 200kHz
( )( ) ( )( ) COSC =
SF =
fOSC
I
∆V fOSC
=
100µA
2.5V fOSC
DC ≅ 0.66 ⇒ 66%
LT1103/LT1105
Setting Overvoltage Lockout
OVLOTH
R2
LT1105
OVLO
R1
LT1103 TA09
CHOOSE OVLOTH
LET R1 = 5k
( ) R2 =
OVLOTH
2.5V
–1
R1
Decreasing Oscillator
Maximum Duty Cycle
5V
LT1105
OSC
COSC
R
I1
LT1103 TA07
CHOOSE 0 ≤ DC ≤ 0.66
(6 – 9DC)
SOLVE FOR X ⇒ X =
2
0 ≤X≤3
⇒ I1 = X • I = X • 100µA
⇒R=
1.75V
I1
( )( ) ( ) COSC =
100µA
2.5V fOSC
•
1+
3X – 2X2
9
Increasing Oscillator
Maximum Duty Cycle
Synchronizing Oscillator Frequency
to an External Clock
LT1103/LT1105
OSC
COSC
R I1
LT1103 TA06
CHOOSE 0.66 ≤ DC ≤ 1.0
(9DC – 6)
SOLVE FOR X ⇒ X =
2
0 ≤ X ≤ 1.5
⇒ I1 = X • I = X • 100µA
⇒R=
3.25V
I1
( )( ) ( ) COSC =
100µA
2.5V fOSC
•
1–
3X + 2X2
9
LT1103/LT1105
500ns
5V
OSC
1µF
0V
1:0.5
COSC
LT1103 TA08
ISOLATION
BOUNDARY
27
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