KA3842 Ver la hoja de datos (PDF) - Fairchild Semiconductor

Número de pieza

componentes Descripción

Fabricante

KA3842

SMPS Controller

Fairchild Semiconductor 

KA3842B/KA3843B/KA3844B/KA3845B

Electrical Characteristics (Continued)

(VCC=15V, RT=10KΩ, CT=3.3nF, TA= 0°C to +70°C unless otherwise specified)

Parameter

PWM SECTION

Max. Duty Cycle

Min. Duty Cycle

TOTAL STANDBY CURRENT

Start-Up Current

Operating Supply Current

Zener Voltage

Symbol

D(max)

D

D(MIN)

IST

ICC(OPR)

VZ

Conditions

KA3842B/KA3843B

KA3844B/KA3845B

-

-

V3=V2=ON

ICC = 25mA

Adjust VCC above the start threshould before setting at 15V

Note:

1. Parameter measured at trip point of latch

2. Gain defined as:

A = ∆∆-----VV----13-

,0 ≤ V3 ≤ 0.8V

3.These parameters, although guaranteed, are not 100 tested in production.

Min. Typ. Max. Unit

95 97 100 %

47 48 50 %

-

-

0

%

- 0.45 1 mA

-

14 17 mA

30

38

-

V

Figure 1. Open Loop Test Circuit

High peak currents associated with capacitive loads necessitate careful grounding techniques Timing and bypass capacitors

should be connected close to pin 5 in a single point ground. The transistor and 5KΩ potentiometer are used to sample the

oscillator waveform and apply an adjustable ramp to pin 3.

4

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