ML4821CS Fairchild Optoelectronics Group, ML4821CS Datasheet - Page 6

• Manufacturer Part Number: ML4821CS
• Description: IC CONTROLLER PFC 5V 35MA 20SOIC
• Manufacturer: Fairchild Optoelectronics Group

Specifications of ML4821CS

• Mode: Average Current
• Frequency - Switching: 1MHz
• Current - Startup: 600µA
• Voltage - Supply: 12 V ~ 18 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q1324911

ML4821
Functional Description
Oscillator
6
RAMP VALLEY
T
T
T
RAMP PEAK
OSC
RAMP
DISCHARGE
CLOCK
= T
= C(Ramp Valley to Peak) ÷ (I
R
C
RAMP
Figure 1. Oscillator Block Diagram
T
T
C
T
= C(Ramp Valley to Pk) ÷ (8.4mA – I
+ T
DISCHARGE
C
R
8.4mA
T
T
SYNC
I
R T
t
D
Q1
2kΩ
1kΩ
RT
I
R T
2
+
–
/2)
Q2
V
REF
RT
/2)
VOLTAGE and Current ERROR Amplifiers
Output Driver Stage
Gain Modulator
Figure 2. Oscillator Timing Resistance vs. Frequency
1000
100
10
0
10
1nF
20
R
T
(kΩ)
150pF
PRODUCT SPECIFICATION
30
680pF
REV. 1.0.2 6/19/01
330pF
40
470pF
50