LM2593HV
SIMPLE SWITCHER
®
Power Converter 150 kHz 2A
Step-Down Voltage Regulator, with Features
General Description
The LM2593HV series of regulators are monolithic inte-
grated circuits that provide all the active functions for a
step-down (buck) switching regulator, capable of driving a
2A load with excellent line and load regulation. These de-
vices are available in fixed output voltages of 3.3V, 5V, and
an adjustable output version.
This series of switching regulators is similar to the
LM2592HV with additional supervisory and performance fea-
tures.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation
†
, improved line and load specifications,
fixed-frequency oscillator, Shutdown/Soft-start, output error
flag and flag delay.
The LM2593HV operates at a switching frequency of 150
kHz thus allowing smaller sized filter components than what
would be needed with lower frequency switching regulators.
Available in a standard 7-lead TO-220 package with several
different lead bend options, and a 7-lead TO-263 Surface
mount package.
Other features include a guaranteed
±
4% tolerance on out-
put voltage under all conditions of input voltage and output
load conditions, and
±
15% on the oscillator frequency. Ex-
ternal shutdown is included, featuring typically 90 µA
standby current. Self protection features include a two stage
current limit for the output switch and an over temperature
shutdown for complete protection under fault conditions.
Features
n
3.3V, 5V, and adjustable output versions
n
Adjustable version output voltage range, 1.2V to 57V
±
4% max over line and load conditions
n
Guaranteed 2A output load current
n
Available in 7-pin TO-220 and TO-263 (surface mount)
Package
n
Input voltage range up to 60V
n
150 kHz fixed frequency internal oscillator
n
Shutdown/Soft-start
n
Out of regulation error flag
n
Error flag delay
n
Low power standby mode, I
Q
typically 90 µA
n
High Efficiency
n
Thermal shutdown and current limit protection
Applications
n
Simple high-efficiency step-down (buck) regulator
n
Efficient pre-regulator for linear regulators
n
On-card switching regulators
n
Positive to Negative converter
Note:
†
Patent Number 5,382,918.
Typical Application
(Fixed Output Voltage Versions)
10133301
SIMPLE SWITCHER
®
and
Switchers Made Simple
®
are registered trademarks of National Semiconductor Corporation.
December 2001
LM2593HV
SIMPLE
SWITCHER
Power
Converter
150
kHz
2A
Step-Down
V
oltage
Regulator
,
with
Features
© 2001 National Semiconductor Corporation
DS101333
www.national.com
Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Maximum Supply Voltage (V
IN
)
63V
6V
1.5V
Flag Pin Voltage
−0.3
≤
V
≤
45V
Feedback Pin Voltage
−0.3
≤
V
≤
+25V
Output Voltage to Ground
(Steady State)
−1V
Power Dissipation
Internally limited
Storage Temperature Range
−65˚C to +150˚C
ESD Susceptibility
2 kV
Lead Temperature
S Package
Vapor Phase (60 sec.)
+215˚C
Infrared (10 sec.)
+245˚C
T Package (Soldering, 10 sec.)
+260˚C
Maximum Junction Temperature
+150˚C
Operating Conditions
Temperature Range
−40˚C
≤
T
J
≤
+125˚C
Supply Voltage
4.5V to 60V
LM2593HV-3.3
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
LM2593HV-3.3
Units
(Limits)
Typ
Limit
V
OUT
Output Voltage
4.75V
≤
V
IN
≤
60V, 0.2A
≤
I
LOAD
≤
2A
3.3
V
3.168/3.135
V(min)
3.432/3.465
V(max)
η
Efficiency
V
IN
= 12V, I
LOAD
= 2A
76
LM2593HV-5.0
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
LM2593HV-5.0
Units
(Limits)
Typ
Limit
V
OUT
Output Voltage
7V
≤
V
IN
≤
60V, 0.2A
≤
I
LOAD
≤
2A
5
V
4.800/4.750
V(min)
5.200/5.250
V(max)
η
Efficiency
V
IN
= 12V, I
LOAD
= 2A
81
%
LM2593HV-ADJ
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
LM2593HV-ADJ
Units
(Limits)
Typ
Limit
V
FB
Feedback Voltage
4.5V
≤
V
IN
≤
60V, 0.2A
≤
I
LOAD
≤
2A
1.230
V
V
OUT
programmed for 3V. Circuit of
1.193/1.180
V(min)
1.267/1.280
V(max)
LM2593HV
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2
LM2593HV-ADJ
Electrical Characteristics
(Continued)
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
LM2593HV-ADJ
Units
(Limits)
Typ
Limit
η
Efficiency
V
IN
= 12V, V
OUT
= 3V, I
LOAD
= 2A
75
%
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 Tempera-
ture Range. Unless otherwise specified, V
IN
= 12V for the 3.3V, 5V, and Adjustable version. I
LOAD
= 500 mA
Symbol
Parameter
Conditions
LM2593HV-XX
Units
(Limits)
Typ
Limit
DEVICE PARAMETERS
I
b
Feedback Bias Current
Adjustable Version Only, V
FB
= 1.3V
10
nA
50/100
nA (max)
f
O
Oscillator Frequency
150
kHz
127/110
kHz(min)
173/173
kHz(max)
V
SAT
Saturation Voltage
I
OUT
1.10
V
1.3/1.4
V(max)
DC
Max Duty Cycle (ON)
100
%
Min Duty Cycle (OFF)
0
I
CLIM
Switch current Limit
3.0
A
2.4/2.3
A(min)
3.7/4.0
A(max)
I
L
Output Leakage Current
Output = 0V
50
µA(max)
Output = −1V
5
mA
30
mA(max)
I
Q
Operating Quiescent
5
mA
Current
10
mA(max)
I
STBY
Standby Quiescent
SD /SS pin = 0V
90
µA
Current
200/250
µA(max)
θ
JC
Thermal Resistance
TO220 or TO263 Package, Junction to Case
2
˚C/W
θ
JA
50
˚C/W
θ
JA
50
˚C/W
θ
JA
30
˚C/W
θ
JA
20
˚C/W
SHUTDOWN/SOFT-START CONTROL Test Circuit of
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
1.5
µA
5
µA(max)
LM2593HV
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3
All Output Voltage Versions
Electrical Characteristics
(Continued)
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range. Unless otherwise specified, V
IN
= 12V for the 3.3V, 5V, and Adjustable version. I
LOAD
= 500 mA
Symbol
Parameter
Conditions
LM2593HV-XX
Units
(Limits)
Typ
Limit
FLAG/DELAY CONTROL Test Circuit of
Regulator Dropout Detector
Low (Flag ON)
96
%
Threshold Voltage
92
%(min)
98
%(max)
VF
SAT
Flag Output Saturation
I
SINK
= 3 mA
0.3
V
Voltage
V
DELAY
= 0.5V
0.7/1.0
V(max)
IF
L
Flag Output Leakage Current
V
FLAG
= 60V
0.3
µA
Delay Pin Threshold
1.25
V
Voltage
Low (Flag ON)
1.21
V(min)
High (Flag OFF) and V
OUT
Regulated
1.29
V(max)
Delay Pin Source Current
V
DELAY
= 0.5V
3
µA
6
µA(max)
Delay Pin Saturation
Low (Flag ON)
70
mV
350/400
mV(max)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: Voltage internally clamped. If clamp voltage is exceeded, limit current to a maximum of 1 mA.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5k resistor into each pin.
Note 4: Typical numbers are at 25˚C and represent the most likely norm.
Note 5: All limits guaranteed 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 guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used
to calculate Average Outgoing Quality Level (AOQL).
Note 6: External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the
LM2593HV is used as shown in the
test circuit, system performance will be as shown in system parameters section of Electrical Characteristics.
Note 7: 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.
Note 8: No diode, inductor or capacitor connected to output pin.
Note 9: Feedback pin removed from output and connected to 0V to force the output transistor switch ON.
Note 10: Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the ADJ. version to force the output transistor switch OFF.
Note 11: V
IN
= 60V.
Note 12: Junction to ambient thermal resistance (no external heat sink) for the package mounted TO-220 package mounted vertically, with the leads soldered to
a printed circuit board with (1 oz.) copper area of approximately 1 in
2
.
Note 13: Junction to ambient thermal resistance with the TO-263 package tab soldered to a single sided printed circuit board with 0.5 in
2
of (1 oz.) copper area.
Note 14: Junction to ambient thermal resistance with the TO-263 package tab soldered to a single sided printed circuit board with 2.5 in
2
of (1 oz.) copper area.
Note 15: Junction to ambient thermal resistance with the TO-263 package tab soldered to a double sided printed circuit board with 3 in
2
of (1 oz.) copper area on
the LM2593HVS side of the board, and approximately 16 in
2
of copper on the other side of the p-c board. See application hints in this data sheet and the thermal
model in Switchers Made Simple available at http://power.national.com.
LM2593HV
www.national.com
4
Typical Performance Characteristics
(Circuit of
Normalized
Output Voltage
Line Regulation
Efficiency
10133302
10133303
10133304
Switch Saturation
Voltage
Switch Current Limit
Dropout Voltage
10133305
10133306
10133307
Operating
Quiescent Current
Shutdown
Quiescent Current
Minimum Operating
Supply Voltage
10133308
10133309
10133310
LM2593HV
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5
Typical Performance Characteristics
(Circuit of
Feedback Pin
Bias Current
Flag Saturation
Voltage
Switching Frequency
10133311
10133312
10133313
Soft-start
Shutdown /Soft-start
Current
Delay Pin Current
10133314
10133315
10133316
Soft-start Response
Shutdown/Soft-start
Threshold Voltage
Internal Gain-Phase Characteristics
10133318
10133353
10133378
LM2593HV
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6
Typical Performance Characteristics
(Circuit of
Continuous Mode Switching Waveforms
V
IN
= 20V, V
OUT
= 5V, I
LOAD
= 2A
L = 32 µH, C
OUT
= 220 µF, C
OUT
ESR = 50 m
Ω
Discontinuous Mode Switching Waveforms
V
IN
= 20V, V
OUT
= 5V, I
LOAD
= 500 mA
L = 10 µH, C
OUT
= 330 µF, C
OUT
ESR = 45 m
Ω
10133320
Horizontal Time Base: 2 µs/div.
A: Output Pin Voltage, 10V/div.
B: Inductor Current 1A/div.
C: Output Ripple Voltage, 50 mV/div.
10133319
Horizontal Time Base: 2 µs/div.
A: Output Pin Voltage, 10V/div.
B: Inductor Current 0.5A/div.
C: Output Ripple Voltage, 100 mV/div.
Load Transient Response for Continuous Mode
V
IN
= 20V, V
OUT
= 5V, I
LOAD
= 500 mA to 2A
L = 32 µH, C
OUT
= 220 µF, C
OUT
ESR = 50 m
Ω
Load Transient Response for Discontinuous Mode
V
IN
= 20V, V
OUT
= 5V, I
LOAD
= 500 mA to 2A
L = 10 µH, C
OUT
= 330 µF, C
OUT
ESR = 45 m
Ω
10133321
Horizontal Time Base: 50 µs/div.
A: Output Voltage, 100 mV/div. (AC)
B: 500 mA to 2A Load Pulse
10133322
Horizontal Time Base: 200 µs/div.
A: Output Voltage, 100 mV/div. (AC)
B: 500 mA to 2A Load Pulse
Connection Diagrams and Order Information
Bent and Staggered Leads, Through Hole Package
7-Lead TO-220 (T)
Surface Mount Package
7-Lead TO-263 (S)
10133350
Order Number LM2593HVT-3.3, LM2593HVT-5.0,
or LM2593HVT-ADJ
See NS Package Number TA07B
10133323
Order Number LM2593HVS-3.3, LM2593HVS-5.0,
or LM2593HVS-ADJ
See NS Package Number TS7B
LM2593HV
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7
Test Circuit and Layout Guidelines
Fixed Output Voltage Versions
10133324
Component Values shown are for V
IN
= 15V,
V
OUT
= 5V, I
LOAD
= 2A.
C
IN
—
470 µF, 50V, Aluminum Electrolytic Nichicon “PM Series”
C
OUT
—
220 µF, 25V Aluminum Electrolytic, Nichicon “PM Series”
D1
—
3.3A, 60V Schottky Rectifier, 31DQ06 (International Rectifier)
L1
—
33 µH, See Inductor Selection Procedure
Adjustable Output Voltage Versions
10133325
Select R
1
to be approximately 1 k
Ω
, use a 1% resistor for best stability.
Component Values shown are for V
IN
= 20V,
V
OUT
= 10V, I
LOAD
= 2A.
C
IN
:
— 470 µF, 35V, Aluminum Electrolytic Nichicon “PM Series”
C
OUT
:
— 220 µF, 35V Aluminum Electrolytic, Nichicon “PM Series”
D1 — 3.3A, 60V Schottky Rectifier, 31DQ06 (International Rectifier)
L1 — 47 µH, See Inductor Selection Procedure
R
1
— 1 k
Ω
, 1%
R
2
— 7.15k, 1%
C
FF
— 3.3 nF
Typical Values
C
SS
— 0.1 µF
C
DELAY
— 0.1 µF
R
PULL UP
— 4.7k (use 22k if V
OUT
is
≥
45V)
†
Resistive divider is required to aviod exceeding maximum rating of 45V/3mA on/into flag pin.
††
Small signal Schottky diode to prevent damage to feedback pin by negative spike when output is shorted (C
FF
not being able to discharge immediately will
drag feedback pin below ground). Required if V
IN
>
40V
FIGURE 1. Standard Test Circuits and Layout Guides
LM2593HV
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8
Block Diagram
10133330
PIN FUNCTIONS
+V
IN
(Pin 1) — This is the positive input supply for the IC
switching regulator. A suitable input bypass capacitor must
be present at this pin to minimize voltage transients and to
supply the switching currents needed by the regulator.
Output (Pin 2) — Internal switch. The voltage at this pin
switches between approximately (+V
IN
− V
SAT
) and approxi-
mately −0.5V, with a duty cycle of V
OUT
/V
IN
.
Error Flag (Pin 3) — Open collector output that goes active
low (
≤
1.0V) when the output of the switching regulator is out
of regulation (less than 95% of its nominal value). In this
state it can sink maximum 3mA. When not low, it can be
pulled high to signal that the output of the regulator is in
regulation (power good). During power-up, it can be pro-
grammed to go high after a certain delay as set by the Delay
pin (Pin 5). The maximum rating of this pin should not be
exceeded, so if the rail to which it will be pulled-up to is
higher than 45V, a resistive divider must be used instead of
a single pull-up resistor, as indicated in
Ground (Pin 4) — Circuit ground.
Delay (Pin 5) — This sets a programmable power-up delay
from the moment that the output reaches regulation, to the
high signal output (power good) on Pin 3. A capacitor on this
pin starts charging up by means on an internal (
)
3 µA)
current source when the regulated output rises to within 5%
of its nominal value. Pin 3 goes high (with an external
pull-up) when the voltage on the capacitor on Pin 5 exceeds
1.3V. The voltage on this pin is clamped internally to about
1.7V. If the regulated output drops out of regulation (less
than 95% of its nominal value), the capacitor on Pin 5 is
rapidly discharged internally and Pin 3 will be forced low in
about 1/1000
th
of the set power-up delay time.
Feedback (Pin 6) — Senses the regulated output voltage to
complete the feedback loop. This pin is directly connected to
the Output for the fixed voltage versions, but is set to 1.23V
by means of a resistive divider from the output for the
Adjustable version. If a feedforward capacitor is used (Ad-
justable version), then a negative voltage spike is generated
on this pin whenever the output is shorted. This happens
because the feedforward capacitor cannot discharge fast
enough, and since one end of it is dragged to Ground, the
other end goes momentarily negative. To prevent the energy
rating of this pin from being exceeded, a small-signal Schot-
tky diode to Ground is recommended for DC input voltages
above 40V whenever a feedforward capacitor is present
(See
Figure 1). Feedforward capacitor values larger than 0.1
µF are not recommended for the same reason, whatever be
the DC input voltage.
Shutdown /Soft-start (Pin 7) — The regulator is in shut-
down mode, drawing about 90 µA, when this pin is driven to
a low level (
≤
0.6V), and is in normal operation when this Pin
is left floating (internal pull-up) or driven to a high level (
≥
2.0V). The typical value of the threshold is 1.3V and the pin
is internally clamped to a maximum of about 7V. If it is driven
higher than the clamp voltage, it must be ensured by means
of an external resistor that the current into the pin does not
exceed 1mA. The duty cycle is minimum (0%) if this Pin is
below 1.8V, and increases as the voltage on the pin is
increased. The maximum duty cycle (100%) occurs when
this pin is at 2.8V or higher. So adding a capacitor to this pin
produces a softstart feature. An internal current source will
charge the capacitor from zero to its internally clamped
value. The charging current is about 5 µA when the pin is
below 1.3V but is reduced to only 1.6 µA above 1.3V, so as
to allow the use of smaller softstart capacitors.
LM2593HV
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9
PIN FUNCTIONS
(Continued)
Note If any of the above three features (Shutdown
/Soft-start, Error Flag, or Delay) are not used, the respective
pins can be left open.
10133331
FIGURE 2. Soft-Start, Delay, Error Output
LM2593HV
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10
INDUCTOR VALUE SELECTION GUIDES
(For Continuous Mode Operation)
10133332
FIGURE 3. Timing Diagram for 5V Output
10133365
FIGURE 4. LM2593HV-3.3
LM2593HV
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11
INDUCTOR VALUE SELECTION GUIDES
(For Continuous Mode Operation) (Continued)
10133366
FIGURE 5. LM2593HV-5.0
10133367
FIGURE 6. LM2593HV-ADJ
LM2593HV
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12
INDUCTOR VALUE SELECTION GUIDES
(For Continuous Mode Operation) (Continued)
10133368
FIGURE 7. Current Ripple Ratio
Coilcraft Inc.
Phone
(USA): 1-800-322-2645
Web Address
http://www.coilcraft.com
Coilcraft Inc., Europe
Phone
(UK): 1-236-730595
Web Address
http://www.coilcraft-europe.com
Pulse Engineering Inc.
Phone
(USA): 1-858-674-8100
Web Address
http://www.pulseeng.com
Pulse Engineering Inc.,
Phone
(UK): 1-483-401700
Europe
Web Address
http://www.pulseeng.com
Renco Electronics Inc.
Phone
(USA): 1-321-637-1000
Web Address
http://www.rencousa.com
Schott Corp.
Phone
(USA): 1-952-475-1173
Web Address
http://www.shottcorp.com
Cooper Electronic Tech.
(Coiltronics)
Phone
(USA): 1-888-414-2645
Web Address
http://www.cooperet.com
FIGURE 8. Contact Information for Suggested Inductor Manufacturers
LM2593HV
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13
Application Information
INDUCTOR SELECTION PROCEDURE
Application Note AN-1197 titled ’Selecting Inductors for Buck
Converters’ provides detailed information on this topic. For a
quick-start the designer may refer to the nomographs pro-
vided in
Designer to a more general selection of available inductors,
the nomographs provide the required inductance and also
the energy in the core expressed in microjoules (µJ), as an
alternative to just prescribing custom parts. The following
points need to be highlighted:
1.
The Energy values shown on the nomographs apply to
steady operation at the corresponding x-coordinate
(rated maximum load current). However under start-up,
without soft-start, or a short-circuit on the output, the
current in the inductor will momentarily/repetitively hit
the current limit I
CLIM
of the device, and this current
could be much higher than the rated load, I
LOAD
. This
represents an overload situation, and can cause the
Inductor to saturate (if it has been designed only to
handle the energy of steady operation). However most
types of core structures used for such applications have
a large inherent air gap (for example powdered iron
types or ferrite rod inductors), and so the inductance
does not fall off too sharply under an overload. The
device is usually able to protect itself by not allowing the
current to ever exceed I
CLIM
. But if the DC input voltage
to the regulator is over 40V, the current can slew up so
fast under core saturation, that the device may not be
able to act fast enough to restrict the current. The cur-
rent can then rise without limit till destruction of the
device takes place.
Therefore to ensure reliability, it is
recommended, that if the DC Input Voltage exceeds
40V, the inductor must ALWAYS be sized to handle an
instantaneous current equal to I
CLIM
without saturating,
irrespective of the type of core structure/material.
2.
The Energy under steady operation is
where L is in µH and I
PEAK
is the peak of the inductor current
waveform with the regulator delivering I