UC2845BD1 View Datasheet(PDF) - ON Semiconductor
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UC2845BD1 Datasheet PDF : 20 Pages
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UC3844B, UC3845B, UC2844B, UC2845B
ELECTRICAL CHARACTERISTICS (VCC = 15 V [Note 8], RT = 10 k, CT = 3.3 nF. For typical values TA = 25°C, for min/max values
TA is the operating ambient temperature range that applies [Note 9], unless otherwise noted.)
UC284XB
UC384XB, XBV
Characteristic
Symbol
Min Typ Max Min Typ Max Unit
PWM SECTION
Duty Cycle
Maximum (UC284XB, UC384XB)
Maximum (UC384XBV)
Minimum
TOTAL DEVICE
Power Supply Current
Startup (VCC = 6.5 V for UCX845B,
Startup (VCC = 14 V for UCX844B, BV)
Operating (Note 8)
DC(max)
DC(min)
ICC
%
47
48
50
47
48
50
−
−
−
46
48
50
−
−
0
−
−
0
mA
−
0.3 0.5
−
0.3 0.5
−
12
17
−
12
17
Power Supply Zener Voltage (ICC = 25 mA)
VZ
30
36
−
30
36
−
V
8. Adjust VCC above the Startup threshold before setting to 15 V.
9. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
Tlow = 0°C for UC3844B, UC3845B
= − 25°C for UC2844B, UC2845B
Thigh = + 70°C for UC3844B, UC3845B
= + 85°C for UC2844B, UC2845B
= − 40°C for UC3844BV, UC3845BV
= +105°C for UC3844BV, UC3845BV
80
50
20
8.0
VCC = 15 V
TA = 25°C
75
ÄÄÄÄÄ 1. CT = 10 nF
ÄÄÄÄÄ 2. CT = 5.0 nF
70 3. CT = 2.0 nF
ÄÄÄÄÄ 4. CT = 1.0 nF
5. CT = 500 pF
ÄÄÄÄÄ 65 6. CT = 200 pF
ÄÄÄÄÄ 7. CT = 100 pF
3
24
1
5.0
60
7
2.0
NOTE: Output switches at
1/2 the oscillator frequency
0.8
10 k 20 k
50 k
100 k
200 k
500 k
fOSC, OSCILLATOR FREQUENCY (kHz)
1.0 M
55
50
10 k
5
6
20 k
50 k 100 k 200 k
500 k 1.0 M
fOSC, OSCILLATOR FREQUENCY (kHz)
Figure 2. Timing Resistor
versus Oscillator Frequency
Figure 3. Output Deadtime
versus Oscillator Frequency
2.55 V
2.5 V
VCC = 15 V
AV = −1.0
TA = 25°C
3.0 V
2.5 V
VCC = 15 V
AV = −1.0
TA = 25°C
2.45 V
0.5 ms/DIV
Figure 4. Error Amp Small Signal
Transient Response
2.0 V
1.0 ms/DIV
Figure 5. Error Amp Large Signal
Transient Response
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