MB39A104
13
■
SETTING THE OUTPUT VOLTAGE
■
SETTING THE TRIANGULAR OSCILLATION FREQUENCY
The triangular oscillation frequency is determined by the timing capacitor (CT) connected to the CT terminal (pin
13), and the timing resistor (R
T) connected to the RT terminal (pin 12).
Moreover, it shifts more greatly than the caluculated values according to the constant of timing resistor (R
T) when
the triangular wave oscillation frequency exceeds 1 MHz. Therefore, set it referring to “Triangular Wave Oscillation
Frequency vs. Timing Resistor” and “Triangular Wave Oscillation Frequency vs. Timing Capacitor” in “■ TYPICAL
CHARACTERISTICS”.
Triangular oscillation frequency : f
OSC
−
+
+
15
10
14
(CS2)
CS1
(−INE2)
−INE1
VO
R1
R2
1.24 V
Error Amp
1.24
R2
VO (V) =
(R1 + R2)
11
• Output Voltage Setting Circuit
fOSC (kHz) :=
1200000
C
T (pF) •RT (kΩ)
