Datasheet

V
REF
9
COMP
S0019-01
C
T
8
R
T
8 mA
10
SYNC
SAWTOOTH CT
OSC SYNC
Output Deadtime (t
d
)
NOTE: Output deadtime is determined by the size of the external capacitor, C
T
, according to the formula:
For large values of R
T
:
Oscillator frequency is approximated by the formula:
Td +
2C
T
8 mA *
3.6
R
T
ƒ
T
+
2
R
T
C
T
Td + 250 C
T
V
REF
6
S0020-01
0.5 mA
−
5 +
Zs
Zf
l
f
< 0.5 mA
V
REF
7
COMP
−20
−10
0
10
20
30
40
50
60
70
80
90
Open-Loop Voltage Gain − dB
0
−180
−90
Open-Loop Phase − °
G001
f − Frequency − Hz
V
IN
= 20 V
T
J
= 25°
10M1k 10k100 100k 1M
UC2856Q
SGLS265A –NOVEMBER 2004– REVISED MAY 2011 www.ti.com
APPLICATION AND OPERATION INFORMATION
Figure 1. Oscillator Circuit
NOTE: Error Amplifier can source up to 0.5 mA.
Figure 2. Error Amplifier Output Configuration Figure 3. Error Amplifier Gain and Phase vs
Frequency
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