Datasheet

L4978
4/13
Table 6. Electrical Characteristcs
(T
j
= 25°C, C
osc
= 2.7nF, R
osc
= 20kΩ, V
CC
= 24V, unless otherwise specified). “●" Specification Referred
to T
j
from 0 to 125°C
Symbol Parameter Test Condition Min. Typ. Max. Unit
DYNAMIC CHARACTERISTIC
V
I
Operating input voltage range V
o
= 3.3 to 50V; I
o
= 2A
●
8 55 V
V
o
Output voltage I
o
= 0.5A 3.33 3.36 3.39 V
I
o
= 0.2 to 2A
V
cc
= 8 to 55V
3.292 3.36 3.427 V
●
3.22 3.36 3.5 V
V
d
Dropout voltage V
cc
= 10V; I
o
= 2A 0.58 0.733 V
●
1.173 V
I
l
Maximum limiting current V
cc
= 8 to 55V
●
2.5 3 3.5 A
Efficiency V
o
= 3.3V; I
o
= 2A 87 %
f
s
Switching frequency
●
90 100 110 KHz
SVRR Supply voltage ripple rejection V
i
= V
cc
+2V
RMS
; V
o
= V
ref
;
I
o
= 2.5A; f
ripple
= 100Hz
60 dB
Switching Frequency Stability
vs. V
cc
V
cc
= 8 to 55V 3 6 %
Temp. stability of switching
frequency
T
j
= 0 to 125°C 4 %
SOFT START
Soft start charge current 30 40 50 µA
Soft start discharge current 6 10 14 µA
INHIBIT
V
LL
Low level voltage
●
0.9 V
I
sLL
Isource Low level
●
5 15 µA
DC CHARACTERISTICS
I
qop
Total operating quiescent
current
4 6 mA
I
q
Quiescent current Duty Cycle = 0; VFB= 3.8V 2.5 3.5 mA
I
qst-by
Total stand-by quiescent
current
V
inh
< 0.9V 100 200 µA
V
cc
= 55V; V
inh
<0.9V 150 300 µA
ERROR AMPLIFIER
V
FB
Voltage Feedback Input 3.33 3.36 3.39 V
R
L
Line regulation V
cc
= 8 to 55V 5 10 mV
Ref. voltage stability vs
temperature
●
0.4 mV/°C
V
oH
High level output voltage V
FB
= 2.5V 10.3 V
V
oL
Low level output voltage V
FB
= 3.8V 0.65 V
I
o source
Source output current V
comp
= 6V; V
FB
= 2.5V 180 220 µA
I
o sink
Sink output current V
comp
= 6V; V
FB
= 3.8V 200 300 µA
I
b
Source bias current 2 3 µA
SVRR E/A Supply voltage ripple rejection V
comp
= V
FB
; V
cc
= 8 to 55V 60 80 dB
DC open loop gain
R
L
= ∞
50 57 dB
g
m
Transconductance I
comp
= -0.1 to 0.1mA
V
comp
= 6V
2.5 mS