Datasheet

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APPLICATION INFORMATION
Z
i
Z
f
VFB
COMP
2.5 V
0.5 mA
Error
Amplifier
+
−
R
S
C
f
R
f
Error
Amplifier
2R
R 1 V
Current-Sense
Comparator
I
S
(see Note A)
+
−
I
SENSE
COMP
GND
C
T
R
T
V
REF
R
T
/C
T
GND
TL284xB , TL384xB
HIGH-PERFORMANCE CURRENT-MODE PWM CONTROLLERS
SLVS610B – AUGUST 2006 – REVISED JULY 2007
The error-amplifier configuation circuit is shown in Figure 1 .
A. Error amplifier can source or sink up to 0.5 mA.
Figure 1. Error-Amplifier Configuration
The current-sense circuit is shown in Figure 2 .
A. Peak current (I
S
) is determined by the formula: I
S(max)
= 1 V/R
S
B. A small RC filter formed by resistor R
f
and capacitor C
f
may be required to suppress switch transients.
Figure 2. Current-Sense Circuit
The oscillator frequency is set using the circuit shown in Figure 3 . The frequency is calculated as:
f = 1 / R
T
C
T
For R
T
> 5 k Ω :
f ≈ 1.72 / R
T
C
T
Figure 3. Oscillator Section
11
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