UC3845BD STMicroelectronics, UC3845BD Datasheet - Page 5

• Manufacturer Part Number: UC3845BD
• Description: Switching Converters, Regulators & Controllers 0.5mA Current Mode
• Manufacturer: STMicroelectronics

Specifications of UC3845BD

• Output Voltage: 4.90 V to 5.10 V
• Switching Frequency: 52 kHz
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: SMD/SMT
• Package / Case: SO-8
• Duty Cycle (max): 50 %
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

High peak currents associated with capacitive loads
necessitate careful grounding techniques. Timing
and bypass capacitors should be connected close
Figure 2: Timing Resistor vs. Oscillator Fre-
Figure 1: Open Loop Test Circuit.
(K )
RT
0.8
50
20
10
5
2
1
10K
ERROR AMP.
V
T
A
i
=15V
ADJUST
=25˚C
20K
4.7K
4.7K
quency
C
T
30K
=5nF
C
T
=10nF
1K
50K
ADJUST
2N2222
D95IN343
I
100K
SENSE
100K
C
T
5K
=2nF
200K 300K
COMP
I
R
SENSE
R
500K
T
T
V
/C
FB
T
D95IN333
f
OSC
1
2
3
4
V
(KHz)
UC2842B
REF
8
C
T
to pin 5 in a single point ground. The transistor and
5 K potentiometer are used to sample the oscillator
waveform and apply an adjustable ramp to pin 3.
Figure 3: Output Dead-Time vs. Oscillator Fre-
50
30
20
10
%
UC2842B/3B/4B/5B - UC3842B/3B/4B/5B
7
6
5
5
3
2
1
10K
V
OUTPUT
GROUND
i
0.1 F
C
20K
T
quency
=200pF
C
T
30K
=500pF
0.1 F
C
T
50K
=1nF
100K
A
C
T
=10nF
1K
1W
C
200K 300K
T
=100pF
C
T
=5nF
C
T
V
V
OUTPUT
GROUND
V
T
=2nF
A
500K fOSC(KHz)
i
=15V
REF
i
=25˚C
D95IN334
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