IL2596-xx

TECHNICAL DATA
Switching Voltage Regulators
IL2596-xx
Features
 3.3V, 5V, 12V, and adjustable output versions
 Adjustable version output voltage range, 1.2V to 37V
± 4% max over line and load conditions
 Guaranteed 3A output load current
 Input voltage range up to 40V
 Requires only 4 external components
 Excellent line and load regulation specifications
 150kHz fixed frequency internal oscillator
 TTL shutdown capability
 Low power standby mode,
IQ typically 100A
 Thermal shutdown and current limit protection
TO-220-5L
IL2596xxKQ
TO-220-5L
IL2596xxKB
TO-263-5L
IL2596xxD2T
ORDERING INFORMATION
Device
Operating
Temperature Range
IL2596xxD2T
IL2596xxKB
Functions
IL2596xxKQ
TA = -40 to 125 C
for all packages
Package
Packing
TO-263
Tape & Reel
TO-220
Tube
TO-220
Tube
 Simple high-efficiency step-down regulator
 On-card switching regulators
 Positive to negative converter
Description
The IL2596 series of regulators are monolithic integrated circuits that provide all the active
functions for a step-down switching regulator, capable of driving a 3A load with excellent line and
load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V and an
adjustable output version.
Requiring a minimum number of external components, these regulators are simple to use.
The IL2596 series operates at a switching frequency of 150kHz. Available in standard 5-lead TO220 package.
Other features include a guaranteed ± 4% tolerance on output voltage under specified input
voltage and output load conditions, and ± 15% on the oscillator frequency. External shutdown is
included, featuring typically 100A standby current. Self protection features include a two stage
frequency reducing current limit for output switch and an over temperature shutdown for complete
protection under fault conditions. The over temperature shutdown level is about 145oC with 5oC
hysteresis.
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Absolute Maximum Rating
o
(TA = 25 C)
Characteristic
Maximum Input Supply Voltage
ON/OFF Pin Input Voltage
Feedback Pin Voltage
Output Voltage to Ground
Power Dissipation
Storage Temperature Range
Operating Temperature Range
Operating Supply Voltage
Symbol
Value
Unit
VI
VIN
45
-0.3  V  +25
-0.3  V  +25
-1
Internally limited
-65 to +150
40  TJ  +125
4.5 to 40
V
V
V
V
W
o
C
o
C
V
VO
PD
Tstg
TJ
VIN
* Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device.
These are stress ratings only and functional operation of the device at these or any other conditions beyond those
indicated under “recommended operating conditions” is not implied.
Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Typical Aplication (Fixed Output Voltage Versions)
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Electrical Characteristics
o
Unless otherwise specified, TJ = 25 C VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V
for the 12V version. ILOAD = 500mA.
Characteristic
Output Voltage
Symbol
VOUT
Efficiency

Feedback Voltage
VFB
Feedback Bias
Current
ID
Oscillator Frequency
fO
Saturation Voltage
Max Duty Cycle (ON)
Max Duty Cycle
(OFF)
Current Limit
Test Condition
Min
Typ
Max
IL2596–3
4.75V  VIN  40V,
0.2A  ILOAD  3A
3.168
3.3
3.432
IL2596–5
7V  VIN  40V,
0.2A  ILOAD  3A
4.8
5.0
5.2
IL2596–12
15V  VIN  40V,
0.2A  ILOAD  3A
11.52
12.0
12.48
IL2596–3
IL2596–5
IL2596–12
IL2596–A
ILOAD = 3A
ILOAD = 3A
VIN = 25V, ILOAD = 3A
VOUT = 3V, ILOAD = 3A
4.5V  VIN  40V,
0.2A  ILOAD  3A
VOUT programmed for
3V
IL2596-A; VFB = 1.3V
IL2596–A
1.193
110
%
1.267
V
15
50
nA
150
173
kHz
1.4
V
1.16
DC
(Note 1,2)
(Note 2)
100
(Note 3)
%
1.230
IOUT = 3A
Peak Current
V
73
80
90
73
VSAT
ICL
Unit
%
0
3.4
4.5
6.0
A
50
A
(Note 1,2)
Output Leakage
Current
IL
Output = 0V
(Note 1,3)
Output = -1V, VIN = 40V
2
30
mA
(Note 3)
5
10
mA
100
200
A
1.3
0.6
V
A
Quiescent Current
IQ
Standby Quiescent
Current
ISTBY
ON/OFF Pin Logic
Input
Threshold Voltage
VIH
Low (Regulator ON)
VIL
High (Regulator OFF)
ON/OFF Pin Input
IH
VLOGIC = 2.5V (regulator OFF)
5
15
Current
IL
VLOGIC = 0.5V (regulator ON)
0.02
5
ON/OFF pin = 5V (OFF), VIN = 40V
2.0
Note 1: No elements connected to output pin.
Note 2: Feedback pin removed from output and connected to 0V to force the output transistor switch ON.
Note 3: Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the A version, and
15V for the 12V version. To force the output transistor switch OFF.
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Typical Perfomance Characteristics
Iccz vs Tpkg (TO-220)
1
0,8
Vin=41V
Vds, (V)
Iccz (uA)
115
110
105
100
95
90
85
80
-50
Vds vs Tpkg (TO-220)
0,6
Vin=12V
Iout=0,2A
0,4
0,2
-25
0
25
50
75
100
0
-50
125
Tem perature of package, Tpkg (°C)
75
100
125
Vfb vs Tpkg (TO-220)
1,2
Vin=12V
Vfb=1,3V
10
Vfb (V)
Ib (nA)
50
1,25
15
5
Vin=12V
Iout=3A
1,15
1,1
1,05
1
-25
0
25
50
75
100
-50
125
Frequency F vs Tpkg (TO-220)
-25
0
25
50
75
100 125
Tem perature of package, Tpkg (C)
0
25
IL2596-3.3
Vo (V)
Vin=12V
Iout=3A
-25
50
75
100
125
Temperature of package, Tpkg (C)
Tem perature of package, Tpkg (°C)
F (kHz)
25
IL2596-adj
20
150
145
140
135
130
125
120
115
110
105
100
-50
0
Tem perature of package , Tpkg (°C)
Ib (on 4 pin) vs Tpkg (TO-220)
0
-50
-25
Vo vs Tpkg
3,5
3,45
3,4
3,35
3,3
3,25
3,2
3,15
3,1
3,05
3
Vin=12V
Iout=3A
-50
-25
0
25
50
75
100
125
Temperature of package, Tpkg (°C)
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Test Circuits
CIN —470 µF, 50V, Aluminum Electrolytic Nichicon “PL Series”
COUT —220 µF, 25V Aluminum Electrolytic, Nichicon “PL Series”
D1 —5A, 40V Schottky Rectifier, 1N5825
L1 —68 µH, L38
Figure1. Standard Test Circuit for Fixed Output Voltage Versions
where VREF = 1.23V
Select R1 to be approximately 1 kW, use a 1% resistor for best stability.
CIN —470 µF, 50V, Aluminum Electrolytic Nichicon “PL Series”
COUT —220 µF, 35V Aluminum Electrolytic, Nichicon “PL Series”
D1 —5A, 40V Schottky Rectifier, 1N5825
L1 —68 µH, L38
R1 —1 kW, 1%
Figure 2. Standard Test Circuit for Adjustable Output Voltage Versions
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Application Information
Figure 3. Delayed Startup
Figure 4. Undervoltage Lockout for Buck Regulator
DELAYED STARTUP
The circuit in Figure 3 uses the the ON /OFF pin to provide a time delay between the time the input voltage is applied
and the time the output voltage comes up (only the circuitry pertaining to the delayed start up is shown). As the input voltage
rises, the charging of capacitor C1 pulls the ON /OFF pin high, keeping the regulator off. Once the input voltage reaches its final
value and the capacitor stops charging, and resistor R2 pulls the ON /OFF pin low, thus allowing the circuit to start switching.
Resistor R1 is included to limit the maximum voltage applied to the ON /OFF pin (maximum of 25V), reduces power supply noise
sensitivity, and also limits the capacitor, C1, discharge current. When high input ripple voltage exists, avoid long delay time,
because this ripple can be coupled into the ON /OFF pin and cause problems. This delayed startup feature is useful in situations
where the input power source is limited in the amount of current it can deliver. It allows the input voltage to rise to a higher
voltage before the regulator starts operating. Buck regulators require less input current at higher input voltages.
UNDERVOLTAGE LOCKOUT
Some applications require the regulator to remain off until the input voltage reaches a predetermined voltage. An
undervoltage lockout feature applied to a buck regulator is shown in Figure 4, while Figure 5 and 6 applies the same feature to
an inverting circuit. The circuit in Figure 5 features a constant threshold voltage for turn on and turn off (zener voltage plus
approximately one volt). If hysteresis is needed, the circuit in Figure 6 has a turn ON voltage which is different than the turn OFF
voltage. The amount of hysteresis is approximately equal to the value of the output voltage. If zener voltages greater than 25V
are used, an additional 47 kresistor is needed from the ON /OFF pin to the ground pin to stay within the 25V maximum limit of
the ON /OFF pin.
INVERTING REGULATOR
The circuit in Figure 7 converts a positive input voltage to a negative output voltage with a common ground. The circuit
operates by bootstrapping the regulator’s ground pin to the negative output voltage, then grounding the feedback pin, the
regulator senses the inverted output voltage and regulates it.
This circuit has an ON/OFF threshold of approximately 13V.
Figure 5. Undervoltage Lockout for Inverting Regulator
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This example uses the IL2596-5.0 to generate a −5V output, but other output voltages are possible by selecting other
output voltage versions, including the adjustable version. Since this regulator topology can produce an output voltage that is
either greater than or less than the input voltage, the maximum output current greatly depends on both the input and output
voltage. The curve shown in Figure 8 provides a guide as to the amount of output load current possible for the different input
and output voltage conditions.
The maximum voltage appearing across the regulator is the absolute sum of the input and output voltage, and this must
be limited to a maximum of 40V. For example, when converting +20V to −12V, the regulator would see 32V between the input
pin and ground pin. The IL2596 has a maximum input voltage spec of 40V.
Additional diodes are required in this regulator configuration. Diode D1 is used to isolate input voltage ripple or noise
from coupling through the CIN capacitor to the output, under light or no load conditions. Also, this diode isolation changes the
topology to closley resemble a buck configuration thus providing good closed loop stability. A Schottky diode is recommended
for low input voltages, (because of its lower voltage drop) but for higher input voltages, a fast recovery diode could be used.
Without diode D3, when the input voltage is first applied, the charging current of CIN can pull the output positive by
several volts for a short period of time. Adding D3 prevents the output from going positive by more than a diode voltage.
This circuit has hysteresis
Regulator starts switching at VIN = 13V
Regulator stops switching at VIN = 8V
Figure 6. Undervoltage Lockout with Hysteresis for Inverting Regulator
CIN —68 µF/25V Tant. Sprague 595D
470 µF/50V Elec. Panasonic HFQ
COUT —47 µF/20V Tant. Sprague 595D
220 µF/25V Elec. Panasonic HFQ
Figure 7. Inverting −5V Regulator with Delayed Startup
Figure 8. Inverting Regulator Typical Load Current
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Because of differences in the operation of the inverting regulator, the standard design procedure is not used to select the
inductor value. In the majority of designs, a 33 µH, 3.5A inductor is the best choice. Capacitor selection can also be narrowed
down to just a few values. Using the values shown in Figure 7will provide good results in the majority of inverting designs.
This type of inverting regulator can require relatively large amounts of input current when starting up, even with light
loads. Input currents as high as the IL2596 current limit (approx 4.5A) are needed for at least 2 ms or more, until the output
reaches its nominal output voltage. The actual time depends on the output voltage and the size of the output capacitor. Input
power sources that are current limited or sources that can not deliver these currents without getting loaded down, may not work
correctly. Because of the relatively high startup currents required by the inverting topology, the delayed startup feature (C1, R1
and R2) shown in Figure 7 is recommended. By delaying the regulator startup, the input capacitor is allowed to charge up to a
higher voltage before the switcher begins operating. A portion of the high input current needed for startup is now supplied by the
input capacitor (CIN). For severe start up conditions, the input capacitor can be made much larger than normal.
INVERTING REGULATOR SHUTDOWN METHODS
To use the ON /OFF pin in a standard buck configuration is simple, pull it below 1.3V (@25°C, referenced to ground) to
turn regulator ON, pull it above 1.3V to shut the regulator OFF. With the inverting configuration, some level shifting is required,
because the ground pin of the regulator is no longer at ground, but is now setting at the negative output voltage level. Two
different shutdown methods for inverting regulators are shown in Figure 9and 10.
Figure 9. Inverting Regulator Ground Referenced Shutdown
Figure 10. Inverting Regulator Ground Referenced Shutdown using Opto Device
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TO-220-5L
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TO-220-5L (Bent Staggered)
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TO-263-5L
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