Datasheet

LM2597, LM2597HV
SNVS119C –MARCH 1998–REVISED APRIL 2013 www.ti.com
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for T
J
= 25°C, and those with boldface type apply over full Operating
Temperature Range. Unless otherwise specified, V
IN
= 12V for the 3.3V, 5V, and Adjustable version and V
IN
= 24V for the
12V version. I
LOAD
= 100 mA.
Symbol Parameter Conditions LM2597/LM2597HV-XX Units
(Limits)
Typ
(1)
Limit
(2)
DEVICE PARAMETERS
I
b
Feedback Bias Current Adjustable Version Only, V
FB
= 1.235V 10 50/100 nA
f
O
Oscillator Frequency See
(3)
150 kHz
127/110 kHz(min)
173/173 kHz(max)
V
SAT
Saturation Voltage I
OUT
= 0.5A
(4)(5)
0.9 V
1.1/1.2 V(max)
DC Max Duty Cycle (ON) See
(5)
100 %
Min Duty Cycle (OFF)
See
(6)
0
I
CL
Current Limit Peak Current
(4)(5)
0.8 A
0.65/0.58 A(min)
1.3/1.4 A(max)
I
L
Output Leakage Current Output = 0V
(4)(6)(7)
50 μA(max)
Output = −1V 2 mA
15 mA(max)
I
Q
Operating Quiescent SD /SS Pin Open, V
BS
Pin Open
(6)
5 mA
Current
10 mA(max)
I
STBY
Standby Quiescent SD /SS pin = 0V
(6)
LM2597 85 μA
Current
200/250 μA(max)
LM2597HV 140 250/300 μA(max)
θ
JA
Thermal Resistance P Package, Junction to Ambient
(8)
95 °C/W
D Package, Junction to Ambient
(8)
150
SHUTDOWN/SOFT-START CONTROL Test Circuit of Figure 31
V
SD
Shutdown Threshold 1.3 V
Voltage
Low, (Shutdown Mode) 0.6 V(max)
High, (Soft-start Mode) 2 V(min)
V
SS
Soft-start Voltage V
OUT
= 20% of Nominal Output Voltage 2 V
V
OUT
= 100% of Nominal Output Voltage 3
I
SD
Shutdown Current V
SHUTDOWN
= 0.5V 5 μA
10 μA(max)
I
SS
Soft-start Current V
Soft-start
= 2.5V 1.6 μA
5 μA(max)
(1) Typical numbers are at 25°C and represent the most likely norm.
(2) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits
are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control
(SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
(3) The switching frequency is reduced when the second stage current limit is activated. The amount of reduction is determined by the
severity of current overload.
(4) No diode, inductor or capacitor connected to output pin.
(5) Feedback pin removed from output and connected to 0V to force the output transistor switch ON.
(6) Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the ADJ. version, and 15V for the 12V version, to force
the output transistor switch OFF.
(7) V
IN
= 40V for the LM2597 and 60V for the LM2597HV.
(8) Junction to ambient thermal resistance with approximately 1 square inch of printed circuit board copper surrounding the leads. Additional
copper area will lower thermal resistance further. See application hints in this data sheet and the thermal model in Switchers Made
Simple software.
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