L4974A
ELECTRICAL CHARACTERISTICS (refer to the test circuit, TJ = 25°C, Vi = 35V, R4 = 30KΩ,
C9 = 2.7nF, fSW = 100KHztyp, unless otherwise specified)
DYNAMIC CHARACTERISTICS
Symbo l
Vi
Vo
∆Vo
∆Vo
Vd
I20L
η
SVR
f
∆f/∆Vi
∆f/Tj
fmax
Pa ram et er
Input Volt. Range (pin 11)
Output Voltage
Line Regulation
Load Regulation
T est Co nd itions
Vo = Vref to 40V
Io = 3.5A (*)
Vi =15V to 50V
Io = 2A; Vo = Vref
VI = 15V to 50V
Io = 1A; Vo = Vref
VO = Vref Io = 1A to 3.5A
Io = 2A to 3A
Dropout Voltage between Io = 2A
Pin 11 and 20
Io = 3.5A
Max Limiting Current
Vi = 15V to 50V
Vo = Vref to 40V
Efficiency
Io = 3.5A, f = 100KHz
Vo = Vref
Vo = 12V
Supply Voltage Ripple
Rejection
Vi = 2VRMS; Io = 5A
f = 100Hz; Vo = Vref
Switching Frequency
Voltage Stability
Switching
Frequency
of Vi = 15V to 45V
Temperature Stability of
Switching Frequency
Tj = 0 to 125°C
Maximum Operating
Switching Frequency
Vo = Vref R4 = 15KΩ
Io = 3.5A C9 = 2.2nF
(*) Pulse testing with a low duty cycle
Min.
15
T yp.
M ax.
50
Unit
V
5
5.1
5.2
V
12
30
mV
8
25
mV
4
10
mV
0.25
0.4
V
0.45
0.7
4
4.75
5.5
A
80
85
%
90
%
56
60
dB
90
100
110
KHz
2
6
%
1
%
200
KHz
Vref SECTION (pin 13)
Symbo l
V13
∆V13
∆V13
∆ V13
∆T
I13 short
Pa ram et er
Reference Voltage
Line Regulation
T est Cond ition
Vi = 15V to 50V
Load Regulation
I13 = 0 to 1mA
Average
Coefficient
Voltage
Temperature
Reference
Short Circuit Current Limit
Tj = 0°C to 125°C
V13 = 0
Min.
5
T yp.
5.1
10
20
0.4
M ax.
5.2
25
40
Unit
V
mV
mV
mV/°C
70
mA
Fig.
5
5
5
5
5
5
5
Fig.
7
7
7
7
7
VSTART SECTION (pin 15)
Symbo l
V14
∆V14
∆V14
I14 short
Pa ram et er
Reference Voltage
Line Regulation
Load Regulation
Short Circuit Current Limit
T est Cond ition
Vi = 15 to 50V
I14 = 0 to 1mA
V15 = 0V
Min.
11.4
T yp.
12
0.6
50
80
M ax.
12.6
1.4
200
Unit
V
V
mV
mA
Fig.
7
7
7
7
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