UC2844N Просмотр технического описания (PDF) - Motorola => Freescale
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UC2844N Datasheet PDF : 14 Pages
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UC3844, 45 UC2844, 45
ELECTRICAL CHARACTERISTICS (VCC = 15 V, [Note 2], RT = 10 k, CT = 3.3 nF, TA = Tlow to Thigh [Note 3],
unless otherwise noted,)
UC284X
UC384X
Characteristics
Symbol
Min Typ Max Min Typ Max
ERROR AMPLIFIER SECTION
Voltage Feedback Input (VO = 2.5 V)
Input Bias Current (VFB = 2.7 V)
Open Loop Voltage Gain (VO = 2.0 V to 4.0 V)
Unity Gain Bandwidth (TJ = 25°C)
Power Supply Rejection Ratio (VCC = 12 V to 25 V)
Output Current
Sink (VO = 1.1 V, VFB = 2.7 V)
Source (VO = 5.0 V, VFB = 2.3 V)
Output Voltage Swing
High State (RL = 15 k to ground, VFB = 2.3 V)
Low State (RL = 15 k to Vref, VFB = 2.7 V)
CURRENT SENSE SECTION
Current Sense Input Voltage Gain (Notes 4 & 5)
Maximum Current Sense Input Threshold (Note 4)
Power Supply Rejection Ratio
VCC = 12 V to 25 V (Note 4)
Input Bias Current
Propagation Delay (Current Sense Input to Output)
OUTPUT SECTION
Output Voltage
Low State (ISink = 20 mA)
(ISink = 200 mA)
High State (ISink = 20 mA)
(ISink = 200 mA)
Output Voltage with UVLO Activated
VCC = 6.0 V, ISink = 1.0 mA
Output Voltage Rise Time (CL = 1.0 nF, TJ = 25°C)
Output Voltage Fall Time (CL = 1.0 nF, TJ = 25°C)
UNDERVOLTAGE LOCKOUT SECTION
Startup Threshold
UCX844
UCX845
VFB
IIB
AVOL
BW
PSRR
ISink
ISource
VOH
VOL
2.45 2.5 2.55 2.42 2.5 2.58
–
–0.1 –1.0
–
–0.1 –2.0
65
90
–
65
90
–
0.7
1.0
–
0.7
1.0
–
60
70
–
60
70
–
2.0
12
–
2.0
12
–
–0.5 –1.0
–
–0.5 –1.0
–
5.0
6.2
–
5.0
6.2
–
–
0.8
1.1
–
0.8
1.1
AV
Vth
PSRR
2.85 3.0 3.15 2.85 3.0 3.15
0.9
1.0
1.1
0.9
1.0
1.1
–
70
–
–
70
–
IIB
–
–2.0 –10
–
–2.0 –10
tPLH(IN/OUT)
–
150 300
–
150 300
VOL
VOH
VOL(UVLO)
tr
tf
–
0.1
0.4
–
1.6
2.2
12 13.5
–
12 13.4
–
–
0.1
1.1
–
50
150
–
50
150
–
0.1
0.4
–
1.6
2.2
13 13.5
–
12 13.4
–
–
0.1
1.1
–
50
150
–
50
150
Vth
15
16
17 14.5 16 17.5
7.8
8.4
9.0
7.8
8.4
9.0
Minimum Operating Voltage After Turn–On
UCX844
UCX845
VCC(min)
9.0
10
11
8.5
10 11.5
7.0
7.6
8.2
7.0
7.6
8.2
PWM SECTION
Duty Cycle
Maximum
Minimum
DCmax
DCmin
46
48
50
47
48
50
–
–
0
–
–
0
TOTAL DEVICE
Power Supply Current (Note 2)
ICC
Startup:
(VCC = 6.5 V for UCX845A,
(VCC 14 V for UCX844) Operating
–
0.5
1.0
–
0.5
1.0
–
12
17
–
12
17
Power Supply Zener Voltage (ICC = 25 mA)
VZ
30
36
–
30
36
–
NOTES: 2. Adjust VCC above the Startup threshold before setting to 15 V.
3. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible
Tlow = –20°C for UC3844, UC3845
Thigh = +70°C for UC3844, UC3845
Tlow = –25°C for UC2844, UC2845
Thigh = +85°C for UC2844, UC2845
4. This parameter is measured at the latch trip point with VFB = 0 V.
5. Comparator gain is defined as: AV ∆V Output Compensation
∆V Current Sense Input
Unit
V
µA
dB
MHz
dB
mA
V
V/V
V
dB
µA
ns
V
V
ns
ns
V
V
%
mA
V
MOTOROLA ANALOG IC DEVICE DATA
3
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