L4978
ELECTRICAL CHARACTERISTICS (continued)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
DC Characteristics
Iqop
Total operating quiescent
current
4
6
mA
Iq
Quiescent current
Duty Cycle = 0; VFB = 3.8V
Vinh <0.9V
2.5
100
150
3.5
200
300
mA
µA
µA
Iqst-by
Total stand-by quiescent
current
Vcc = 55V; Vinh <0.9V
Error Amplifier
VFB
Voltage Feedback Input
3.33
10.3
3.36
5
3.35
10
V
RL
Line regulation
Vcc = 8 to 55V
mV
Ref. voltage stability vs
temperature
•
0.4
mV/°C
VoH
VoL
High level output voltage
Low level output voltage
Source output current
Sink output current
VFB = 2.5V
V
V
VFB = 3.8V
0.65
3
Io source
Io sink
Ib
Vcomp = 6V; VFB = 2.5V
Vcomp = 6V; VFB = 3.8V
180
200
220
300
2
µA
µA
µA
dB
dB
mS
Source bias current
SVRR E/A Supply voltage ripple rejection
DC open loop gain
V
comp = Vfb; Vcc = 8 to 55V
RL = ∞
comp = -0.1 to 0.1mA
comp = 6V
60
50
80
57
gm
Transconductance
I
V
2.5
OscillatorSection
Ramp Valley
0.78
2
0.85
2.15
9.6
0.92
2.3
V
V
Ramp peak
Vcc = 8V
Vcc = 55V
9
10.2
V
Maximum duty cycle
Maximum Frequency
95
97
%
Duty Cycle = 0%
500
kHz
Rosc = 13kΩ, Cosc = 820pF
4/12
STMICROELECTRONICS [ ST ]
