ISL78215 Datasheet, PDF (8/11 Pages) Intersil Corporation – Improved Industry Standard Single-Ended Current Mode PWM Controller

ISL78215
Typical Performance Curves
1.02
1.01
1.00
0.99
0.98
0.97
-40 -10
20
50
80
110
TEMPERATURE (°C)
FIGURE 1. FREQUENCY vs TEMPERATURE
1.001
1.000
0.999
0.998
0.997
0.996
0.995
-40 -25 -10 5 20 35 50 65 80 95 110
TEMPERATURE (°C)
FIGURE 2. REFERENCE VOLTAGE vs TEMPERATURE
1.002
10³
1.000
0.998
0.996
0.994
-40 -25 -10 5 20 35 50 65 80 95 110
TEMPERATURE (°C)
FIGURE 3. EA REFERENCE vs TEMPERATURE
100
10
100pF
220pF
330pF
470pF
1.0nF
2.2nF
3.3nF
4.7nF
1
10 20 30 40 50 60 70 80 90 100
RT (kΩ)
FIGURE 4. RESISTANCE FOR CT CAPACITOR VALUES
GIVEN
Functional Description
Features
The ISL78215 current mode PWMs make an ideal choice
for low-cost flyback and forward topology applications.
With its greatly improved performance over industry
standard parts, it is the obvious choice for new designs
or existing designs which require updating.
Oscillator
The ISL78215 controllers have a sawtooth oscillator with
a programmable frequency range to 2MHz, which can be
programmed with a resistor from VREF and a capacitor to
GND on the RTCT pin. (Please refer to Figure 4 for the
resistor and capacitance required for a given frequency.)
Soft-Start Operation
Soft-start must be implemented externally. One method,
illustrated in Figure 5, clamps the voltage on COMP.
VREF
COMP
GND
FIGURE 5. SOFT-START
8
FN7673.0
August 16, 2010