Datasheet

ELECTRICAL CHARACTERISTICS
(Unless otherwise specified V
CC
= 18V, C
OSC
= 1nF,
R
OSC
= 24K
Ω
, C
SS
= 1
µ
F, V
CA-OUT
= 3.5V, V
ISENSE
= 0V, V
LFF
= V
REF
, I
AC
= 100
µ
A, V
RMS
= 1V,
V
FEED
= GND, V
IPK
= 1V, V
OVP
= 1V, T
J
= 25
°
C
Symbol Prameter Test Condition Min. Typ. Max. Unit
ERROR AMPLIFIER SECTION
V
IO
Input Offset Voltage –25°C < T
J
< 85°C ±8mV
I
IB
Input Bias Current V
FEED
= 0V -500 -50 500 nA
Open Loop Gain 70 100 dB
V
13H
Output High voltage V
FEED
= 4.7V
I
VA-OUT
= -0.5mA
5.5 6.5 7.5 V
V
13L
Output Low Voltage V
FEED
= 5.5V
I
VA-OUT
= 0.5mA
0.4 1 V
-I
13
Output Source Current V
FEED
= 4.7V; V
VA-OUT
= 3.5V 2 10 mA
I
13
Output Sink Current V
FEED
= 5.5V; V
VA-OUT
= 3.5V 4 20 mA
REFERENCE SECTION
V
ref
Reference Output Voltage –25°C < T
J
< 85°C 4.97 5.1 5.23 V
T
j
= 25°C I
ref
= 0 5.01 5.1 5.19 V
∆V
ref
Load Regulation 1mA ≤ I
ref
≤ 10mA
–25°C < T
J
< 85°C
315mV
∆V
ref
Line Regulation 12V ≤ V
CC
≤ 19V
–25°C < T
J
< 85°C
310mV
I
ref sc
Short Circuit Current V
ref
= 0V 20 30 50 mA
OSCILLATOR SECTION
f
osc
Initial Accuracy T
j
= 25°C 85 100 115 KHz
Frequency Stability 12V ≤ V
CC
≤ 19V
–25°C < T
J
< 85°C
80 100 120 KHz
V
svp
Ramp Valley to Peak 4.7 5 5.3 V
I
18C
Charge Current V
COSC
= 3.5V 0.45 0.55 0.65 mA
I
18D
Discharge Current V
COSC
= 3.5V 11.5 mA
V
18
Ramp Valley Voltage 0.9 1.15 1.4 V
SYNC SECTION
(Only for
L4981A
)
t
W
Output Pulse Width 50% Amplitude 0.3 0.8 µs
I
16
Sink Current with Low Output
Voltage
V
SYNC
= 0.4V
V
COSC
= 0V
0.4 0.8 mA
-I
16
Source Current with High Output
Voltage
V
SYNC
= 4.5V
V
COSC
= 6.7V
16 mA
V
16L
Low Input Voltage 0.9 V
V
16H
High Input Voltage 3.5 V
t
d
Pulse for Synchronization 800 ns
FREQUENCY MODULATION FUNCTION
(Only for
L4981B
)
f
18max
Maximum Oscillation Frequency V
FREQ-MOD
= 0V (Pin 16) I
freq
= 0 85 100 115 KHz
f
18min
Minimum Oscillator Frequency I
FREQ-MOD
= 360µA (Pin 16)
V
VRMS
= 4V (Pin 7)
74 KHz
I
FREQ-MOD
= 180µA (Pin 16)
V
VRMS
= 2V (Pin 7)
76 KHz
SOFT START SECTION
I
SS
Soft Start Source Current V
SS
= 3V 60 100 140 µA
V
12sat
Output Saturation Voltage V
3
= 6V, I
SS
= 2mA 0.1 0.25 V
L4981A - L4981B
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