L4981A - L4981B
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified V
CC
= 18V, C
OSC
= 1nF,
R
OSC
= 24KΩ, C
SS
= 1µF, V
CA-OUT
= 3.5V, V
ISENSE
= 0V, V
LFF
= V
REF
, I
AC
= 100µA, V
RMS
= 1V,
V
FEED
= GND, V
IPK
= 1V, V
OVP
= 1V, T
J
= 25°C
Symbol
V
IO
I
IB
V
13H
V
13L
-I
13
I
13
V
ref
∆V
ref
∆V
ref
I
ref sc
f
osc
Prameter
Input Offset Voltage
Input Bias Current
Open Loop Gain
Output High voltage
Output Low Voltage
Output Source Current
Output Sink Current
Reference Output Voltage
Load Regulation
Line Regulation
Short Circuit Current
Initial Accuracy
Frequency Stability
V
svp
I
18C
I
18D
V
18
t
W
I
16
-I
16
V
16L
V
16H
Ramp Valley to Peak
Charge Current
Discharge Current
Ramp Valley Voltage
Output Pulse Width
Sink Current with Low Output
Voltage
Source Current with High Output
Voltage
Low Input Voltage
High Input Voltage
3.5
800
85
100
74
76
115
50% Amplitude
V
SYNC
= 0.4V
V
COSC
= 0V
V
SYNC
= 4.5V
V
COSC
= 6.7V
V
COSC
= 3.5V
V
COSC
= 3.5V
0.9
0.3
0.4
1
V
FEED
= 4.7V
I
VA-OUT
= -0.5mA
V
FEED
= 5.5V
I
VA-OUT
= 0.5mA
V
FEED
= 4.7V; V
VA-OUT
= 3.5V
V
FEED
= 5.5V; V
VA-OUT
= 3.5V
–25
°
C < T
J
< 85
°
C
T
j
= 25°C I
ref
= 0
1mA
≤
I
ref
≤
10mA
–25°C < T
J
< 85°C
12V
≤
V
CC
≤
19V
–25
°
C < T
J
< 85
°
C
V
ref
= 0V
T
j
= 25°C
12V
≤
V
CC
≤
19V
–25°C < T
J
< 85°C
2
4
4.97
5.01
Test Condition
–25°C < T
J
< 85°C
V
FEED
= 0V
-500
70
5.5
-50
100
6.5
0.4
10
20
5.1
5.1
3
3
20
85
80
4.7
0.45
30
100
100
5
0.55
11.5
1.15
0.8
0.8
6
0.9
1.4
5.23
5.19
15
10
50
115
120
5.3
0.65
7.5
1
Min.
Typ.
Max.
±8
500
Unit
mV
nA
dB
V
V
mA
mA
V
V
mV
mV
mA
KHz
KHz
V
mA
mA
V
µs
mA
mA
V
V
ns
KHz
KHz
KHz
ERROR AMPLIFIER SECTION
REFERENCE SECTION
OSCILLATOR SECTION
SYNC SECTION
(Only for
L4981A)
Pulse for Synchronization
t
d
FREQUENCY MODULATION FUNCTION
(Only for
L4981B
)
f
18max
f
18min
Maximum Oscillation Frequency
Minimum Oscillator Frequency
V
FREQ-MOD
= 0V (Pin 16) I
freq
= 0
I
FREQ-MOD
= 360µA (Pin 16)
V
VRMS
= 4V (Pin 7)
I
FREQ-MOD
= 180µA (Pin 16)
V
VRMS
= 2V (Pin 7)
SOFT START SECTION
I
SS
V
12sat
Soft Start Source Current
Output Saturation Voltage
V
SS
= 3V
V
3
= 6V, I
SS
= 2mA
60
100
0.1
140
0.25
µA
V
4/17
STMICROELECTRONICS [ STMICROELECTRONICS ]
