LM2598-ADJ
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
LM2598-ADJ
Units
(Limits)
Typ
Limit
(Note 4)
1.230
(Note 5)
SYSTEM PARAMETERS (Note 6) Test Circuit Figure 1
VFB
Feedback Voltage
4.5V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 1A
V
VOUT programmed for 3V. Circuit of Figure 12.
1.193/1.180
1.267/1.280
V(min)
V(max)
%
η
Efficiency
VIN = 12V, VOUT = 3V, ILOAD = 1A
78
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V ver-
sion. ILOAD = 200 mA
Symbol
Parameter
Conditions
LM2598-XX
Units
(Limits)
Typ
Limit
(Note 4)
10
(Note 5)
DEVICE PARAMETERS
Ib
Feedback Bias Current
Adjustable Version Only, VFB = 1.3V
(Note 7)
nA
nA(max)
kHz
50/100
fO
Oscillator Frequency
Saturation Voltage
150
127/110
173/173
kHz(min)
kHz(max)
V
VSAT
DC
IOUT = 1A (Note 8) (Note 9)
1
1.2/1.3
V(max)
%
Max Duty Cycle (ON)
Min Duty Cycle (OFF)
Current Limit
(Note 9)
100
0
(Note 10)
ICL
Peak Current, (Note 8) (Note 9)
1.5
A
1.2/1.15
2.4/2.6
50
A(min)
A(max)
µA(max)
mA
IL
Output Leakage Current
Output = 0V (Note 9) (Note 10) (Note 11)
Output = −1V
2
5
15
10
mA(max)
mA
IQ
Operating Quiescent
Current
SD /SS Pin Open, (Note 10)
SD /SS pin = 0V, (Note 11)
mA(max)
µA
ISTBY
Standby Quiescent
Current
85
200/250
µA(max)
˚C/W
θJC
θJA
θJA
θJA
θJA
Thermal Resistance
TO220 or TO263 Package, Junction to Case
TO220 Package, Junction to Ambient (Note 12)
TO263 Package, Junction to Ambient (Note 13)
TO263 Package, Junction to Ambient (Note 14)
TO263 Package, Junction to Ambient (Note 15)
2
50
50
30
20
˚C/W
˚C/W
˚C/W
˚C/W
SHUTDOWN/SOFT-START CONTROL Test Circuit of Figure 1
VSD
Shutdown Threshold
Voltage
1.3
V
Low, (Shutdown Mode)
0.6
2
V(max)
V(min)
V
High, (Soft-start Mode)
VSS
Soft-start Voltage
VOUT = 20% of Nominal Output Voltage
VOUT = 100% of Nominal Output Voltage
2
3
www.national.com
4
NSC [ National Semiconductor ]
