TI TL2575

TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
FEATURES
•
•
•
•
•
•
•
APPLICATIONS
•
•
•
•
Simple High-Efficiency Step-Down (Buck)
Regulators
Pre-Regulators for Linear Regulators
On-Card Switching Regulators
Positive-to-Negative Converters (Buck-Boost)
5
4
3
2
1
GND
•
KTT (TO-263) PACKAGE
(TOP VIEW)
Fixed 3.3-V, 5-V, 12-V, and 15-V Options With
±5% Regulation (Max) Over Line, Load, and
Temperature Conditions
Adjustable Option With a Range of 1.23 V to
37 V (57 V for HV Version) and ±4%
Regulation (Max) Over Line, Load, and
Temperature Conditions
Specified 1-A Output Current
Wide Input Voltage Range…4.75 V to 40 V
(60 V for HV Version)
Require Only Four External Components
(Fixed Versions) and Use Readily Available
Standard Inductors
52-kHz (Typ) Fixed-Frequency Internal
Oscillator
TTL Shutdown Capability With 50-µA (Typ)
Standby Current
High Efficiency…as High as 88% (Typ)
Thermal Shutdown and Current-Limit
Protection With Cycle-by-Cycle Current
Limiting
ON/OFF
FEEDBACK
GND
OUTPUT
VIN
N (PDIP) PACKAGE
(TOP VIEW)
NC
NC
OUTPUT
NC
GND
NC
FEEDBACK
NC
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
VIN
NC
NC
GND
GND
NC
NC
ON/OFF
NC − No internal connection
KV (TO-220 STAGGERED LEADS) PACKAGE
(TOP VIEW)
GND
•
5
4
3
2
1
(SIDE VIEW)
ON/OFF
FEEDBACK
GND
OUTPUT
VIN
Pins 1, 3, 5
Pins 2, 4
DESCRIPTION/ORDERING INFORMATION
The TL2575 and TL2575HV greatly simplify the design of switching power supplies by conveniently providing all
the active functions needed for a step-down (buck) switching regulator in an integrated circuit. Accepting a wide
input voltage range of up to 60 V (HV version) and available in fixed output voltages of 3.3 V, 5 V, 12 V, 15 V, or
an adjustable-output version, the TL2575 and TL2575HV have an integrated switch capable of delivering 1 A of
load current, with excellent line and load regulation. The device also offers internal frequency compensation, a
fixed-frequency oscillator, cycle-by-cycle current limiting, and thermal shutdown. In addition, a manual shutdown
is available via an external ON/OFF pin.
The TL2575 and TL2575HV represent superior alternatives to popular three-terminal linear regulators. Due to
their high efficiency, the devices significantly reduce the size of the heatsink and, in many cases, no heatsink is
required. Optimized for use with standard series of inductors available from several different manufacturers, the
TL2575 and TL2575HV greatly simplify the design of switch-mode power supplies by requiring a minimal
addition of only four to six external components for operation.
The TL2575 and TL2575HV are characterized for operation over the virtual junction temperature range of –40°C
to 125°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2006, Texas Instruments Incorporated
TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
ORDERING INFORMATION
TL2575 (VIN(MAX) = 40 V)
TJ
VO
(NOM)
3.3 V
5V
–40°C to 125°C
12 V
15 V
ADJ
(1)
PACKAGE (1)
ORDERABLE PART NUMBER
TOP-SIDE MARKING
PDIP – N
Tube of 25
TL2575-33IN
TL2575-33IN
TO-263 – KTT
Reel of 2000
TL2575-33IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575-33IKV
PREVIEW
PDIP – N
Tube of 25
TL2575-05IN
TL2575-05IN
TO-263 – KTT
Reel of 2000
TL2575-05IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575-05IKV
PREVIEW
PDIP – N
Tube of 25
TL2575-12IN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575-12IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575-12IKV
PREVIEW
PDIP – N
Tube of 25
TL2575-15IN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575-15IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575-15IKV
PREVIEW
PDIP – N
Tube of 25
TL2575-ADJIN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575-ADJIKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575-ADJIKV
PREVIEW
Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at
www.ti.com/sc/package.
ORDERING INFORMATION
TL2575HV (VIN(MAX) = 60 V)
TJ
VO
(NOM)
3.3 V
5V
–40°C to 125°C
12 V
15 V
ADJ
(1)
2
PACKAGE (1)
ORDERABLE PART NUMBER
TOP-SIDE MARKING
PDIP – N
Tube of 25
TL2575HV-33IN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575HV-33IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575HV-33IKV
PREVIEW
PDIP – N
Tube of 25
TL2575HV-05IN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575HV-05IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575HV-05IKV
PREVIEW
PDIP – N
Tube of 25
TL2575HV-12IN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575HV-12IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575HV-12IKV
PREVIEW
PDIP – N
Tube of 25
TL2575HV-15IN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575HV-15IKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575HV-15IKV
PREVIEW
PDIP – N
Tube of 25
TL2575HV-ADJIN
PREVIEW
TO-263 – KTT
Reel of 2000
TL2575HV-ADJIKTTR
PREVIEW
TO-220 – KV
Tube of 50
TL2575HV-ADJIKV
PREVIEW
Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at
www.ti.com/sc/package.
Submit Documentation Feedback
TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
FUNCTIONAL BLOCK DIAGRAM
VIN
Unregulated
DC Input
Internal
Regulator
1
+
ON/OFF
On/Off
5
CIN
FEEDBACK
4
Fixed-Gain
Error Amplifier
R2
R1
1 k
Comparator
+
_
+
_
Driver
1-A
Switch
OUTPUT
L1
2
+
D1
1.23-V
Band-Gap
Reference
VOUT
COUT
GND
52-kHz
Oscillator
Reset
Thermal
Shutdown
Current
Limit
3
L
O
A
D
3.3 V: R2 = 1.7 k
5 V: R2 = 3.1 k
12 V: R2 = 8.84 k
15 V: R2 = 11.3 k
ADJ: R1 = Open, R2 = 0 Ω
A.
Pin numbers are for the KTT (TO-263) package.
FEEDBACK
4
7-V to 40-V
Unregulated
DC Input
+VIN
TL2575-05
1
3
+
GND
5
OUTPUT
2
L1
L2
330 µH
20 µH
5-V
Regulated
Output
1-A Load
ON/OFF
CIN
100 µF
D1
1N5819
+
COUT
330 µF
C1
100 µF
+
Optional Output Ripple Filter
A.
Pin numbers are for the KTT (TO-263) package.
Figure 1. Typical Application Circuit (Fixed Version)
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TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
Absolute Maximum Ratings (1)
over operating free-air temperature range (unless otherwise noted)
MIN
VIN
Supply voltage
60
TL2575
42
ON/OFF input voltage range
–0.3
Output voltage to GND (steady state)
TJ
Maximum junction temperature
Tstg
Storage temperature range
(1)
MAX
TL2575HV
–65
UNIT
V
VIN
V
–1
V
150
°C
150
°C
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.
Package Thermal Data (1)
PACKAGE
BOARD
θJC
PDIP (N)
High K, JESD 51-7
57°C/W
TO-263 (KTT)
High K, JESD 51-5
TO-220 (KV)
(1)
θJCP
θJA
67°C/W
TBD
TBD
TBD
TBD
Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient
temperature is PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can affect reliability.
Recommended Operating Conditions
4
VIN
Supply voltage
TJ
Operating virtual junction temperature
MIN
MAX
TL2575HV
4.75
60
TL2575
4.75
40
–40
125
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UNIT
V
°C
TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
TL2575 Electrical Characteristics
ILOAD = 200 mA, VIN = 12 V for 3.3-V, 5-V, and adjustable versions, VIN = 25 V for 12-V version, VIN = 30 V for 15-V version
(unless otherwise noted) (see Figure 2)
PARAMETER
TEST CONDITIONS
TL2575-33
TL2575-05
VOUT
Output voltage
TL2575-12
TL2575-15
Feedback voltage
η
Efficiency
TL2575-ADJ
TJ
MAX
VIN = 12 V, ILOAD = 0.2 A
25°C
3.234
3.3
3.366
4.75 V ≤ VIN ≤ 40 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
3.168
3.3
3.432
Full range
3.135
25°C
4.9
5
5.1
8 V ≤ VIN ≤ 40 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
4.8
5
5.2
Full range
4.75
VIN = 25 V, ILOAD = 0.2 A
25°C
11.76
12
12.24
15 V ≤ VIN ≤ 40 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
11.52
12
12.48
5.25
Full range
11.4
VIN = 30 V, ILOAD = 0.2 A
25°C
14.7
15
18 V ≤ VIN ≤ 40 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
14.4
15
15.6
Full range
14.25
15
15.75
25°C
1.217
1.23
1.243
25°C
1.193
1.23
1.267
Full range
1.18
VIN = 12 V, VOUT = 5 V,
ILOAD = 0.2 A
8 V ≤ VIN ≤ 40 V, VOUT = 5 V,
0.2 A ≤ ILOAD ≤ 1 A
VIN = 12 V, ILOAD = 1 A
77
TL2575-12
VIN = 15 V, ILOAD = 1 A
TL2575-15
VIN = 18 V, ILOAD = 1 A
88
TL2575-ADJ
VIN = 12 V, VOUT = 5 V,
ILOAD = 1 A
77
fo
Oscillator frequency (1)
VSAT
Saturation voltage
IOUT = 1 A (2)
ICL
Switch peak current (1) (2)
IL
Output leakage current
25°C
IQ
Quiescent current (4)
ISTBY
Standby quiescent current
VIN =
50
47
Full range
42
25°C
52
0.9
93
98
25°C
1.7
2.8
Full range
1.3
OFF (ON/OFF = 5 V)
58
1.2
1.4
25°C
Output = –1 V
100
63
Full range
25°C
V
%
500
25°C
VIN = 40 (4), Output = 0 V
40 (4),
88
Full range
Maximum duty cycle (3)
15.3
1.28
TL2575-05
VOUT = 5 V (ADJ version only)
V
12.6
75
25°C
UNIT
3.465
VIN = 12 V, ILOAD = 0.2 A
VIN = 12 V, ILOAD = 1 A
Feedback bias current
(2)
(3)
(4)
TYP
TL2575-33
IIB
(1)
TL2575
MIN
kHz
V
%
3.6
4
2
7.5
nA
30
A
mA
25°C
5
10
mA
25°C
50
200
µA
In the event of an output short or an overload condition, self-protection features lower the oscillator frequency to ∼18 kHz and the
minimum duty cycle from 5% to ∼2%. The resulting output voltage drops to ∼40% of its nominal value, causing the average power
dissipated by the IC to lower.
Output is not connected to diode, inductor, or capacitor. Output is sourcing current.
FEEDBACK is disconnected from output and connected to 0 V.
To force the output transistor off, FEEDBACK is disconnected from output and connected to 12 V for the adjustable, 3.3-V, and 5-V
versions and to 25 V for the 12-V and 15-V versions.
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TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
TL2575 Electrical Characteristics (continued)
ILOAD = 200 mA, VIN = 12 V for 3.3-V, 5-V, and adjustable versions, VIN = 25 V for 12-V version, VIN = 30 V for 15-V version
(unless otherwise noted) (see Figure 2)
PARAMETER
6
TEST CONDITIONS
TJ
TL2575
MIN
TYP
25°C
2.2
1.4
Full range
2.4
MAX
UNIT
VIH
ON/OFF high-level logic
input voltage
OFF (VOUT = 0 V)
VIL
ON/OFF low-level logic
input voltage
ON (VOUT = nominal voltage)
IIH
ON/OFF high-level input current
OFF (ON/OFF = 5 V)
25°C
12
30
µA
IIL
ON/OFF low-level input current
ON (ON/OFF = 0 V)
25°C
0
10
µA
25°C
1.2
Full range
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V
1
0.8
V
TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
TL2575HV Electrical Characteristics
ILOAD = 200 mA, VIN = 12 V for 3.3-V, 5-V, and adjustable versions, VIN = 25 V for 12-V version, VIN = 30 V for 15-V version
(unless otherwise noted) (see Figure 2)
PARAMETER
TEST CONDITIONS
TL2575HV-33
TL2575HV-05
VOUT
Output voltage
TL2575HV-12
TL2575HV-15
Feedback voltage
η
Efficiency
TL2575HV-ADJ
TJ
MAX
VIN = 12 V, ILOAD = 0.2 A
25°C
3.234
3.3
3.366
4.75 V ≤ VIN ≤ 60 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
3.168
3.3
3.450
Full range
3.135
25°C
4.9
5
5.1
8 V ≤ VIN ≤ 60 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
4.8
5
5.225
Full range
4.75
VIN = 25 V, ILOAD = 0.2 A
25°C
11.76
12
12.24
15 V ≤ VIN ≤ 60 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
11.52
12
12.54
5.275
Full range
11.4
VIN = 30 V, ILOAD = 0.2 A
25°C
14.7
15
15.3
18 V ≤ VIN ≤ 60 V,
0.2 A ≤ ILOAD ≤ 1 A
25°C
14.4
15
15.68
Full range
14.25
15
15.83
25°C
1.217
1.23
1.243
25°C
1.193
1.23
1.273
Full range
1.180
VIN = 12 V, VOUT = 5 V,
ILOAD = 0.2 A
8 V ≤ VIN ≤ 60 V, VOUT = 5 V,
0.2 A ≤ ILOAD ≤ 1 A
VIN = 12 V, ILOAD = 1 A
77
TL2575HV-12
VIN = 15 V, ILOAD = 1 A
TL2575HV-15
VIN = 18 V, ILOAD = 1 A
88
TL2575HV-ADJ
VIN = 12 V, VOUT = 5 V,
ILOAD = 1 A
77
fo
Oscillator frequency (1)
VSAT
Saturation voltage
IOUT = 1 A (2)
Switch peak current (1) (2)
IL
Output leakage current
47
Full range
42
25°C
IQ
Quiescent current (4)
ISTBY
Standby quiescent current
VIN =
52
0.9
93
98
25°C
1.7
2.8
Full range
1.3
OFF (ON/OFF = 5 V)
58
1.2
1.4
25°C
Output = –1 V
100
63
Full range
25°C
%
500
25°C
VIN = 60 (4), Output = 0 V
60 (4),
50
Full range
Maximum duty cycle (3)
ICL
88
25°C
V
1.286
TL2575HV-05
VOUT = 5 V (ADJ version only)
V
12.66
75
25°C
UNIT
3.482
VIN = 12 V, ILOAD = 0.2 A
VIN = 12 V, ILOAD = 1 A
Feedback bias current
(2)
(3)
(4)
TYP
TL2575HV-33
IIB
(1)
TL2575HV
MIN
kHz
V
%
3.6
4
2
7.5
nA
30
A
mA
25°C
5
10
mA
25°C
50
200
µA
In the event of an output short or an overload condition, self-protection features lower the oscillator frequency to ∼18 kHz and the
minimum duty cycle from 5% to ∼2%. The resulting output voltage drops to ∼40% of its nominal value, causing the average power
dissipated by the IC to lower.
Output is not connected to diode, inductor, or capacitor. Output is sourcing current.
FEEDBACK is disconnected from output and connected to 0 V.
To force the output transistor off, FEEDBACK is disconnected from output and connected to 12 V for the adjustable, 3.3-V, and 5-V
versions and to 25 V for the 12-V and 15-V versions.
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TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
TL2575HV Electrical Characteristics (continued)
ILOAD = 200 mA, VIN = 12 V for 3.3-V, 5-V, and adjustable versions, VIN = 25 V for 12-V version, VIN = 30 V for 15-V version
(unless otherwise noted) (see Figure 2)
PARAMETER
8
TEST CONDITIONS
VIH
ON/OFF high-level logic
input voltage
VIL
ON/OFF low-level logic input voltage ON (VOUT = nominal voltage)
IIH
ON/OFF high-level input current
OFF (ON/OFF = 5 V)
IIL
ON/OFF low-level input current
ON (ON/OFF = 0 V)
OFF (VOUT = 0 V)
TJ
TL2575HV
MIN
TYP
25°C
2.2
1.4
Full range
2.4
25°C
1.2
Full range
Submit Documentation Feedback
25°C
MAX
UNIT
V
1
0.8
V
12
30
µA
0
10
µA
TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
TEST CIRCUITS
Fixed-Output Voltage
FEEDBACK
4
+VIN
TL2575-xx
Fixed Output
1
OUTPUT
3
+
GND
VOUT
330 µH
2
VIN
Unregulated
DC Input
L1
5 ON/OFF
L
O
A
D
D1
CIN
100 µF
+
COUT
330 µF
CIN = 100 µF, Aluminum Electrolytic
COUT = 330 µF, Aluminum Electrolytic
D1 = Schottky
L1 = 330 µH (for 5-V VIN with 3.3-V VOUT, use 100 H)
Adjustable-Output Voltage
+VIN
1
FEEDBACK
4
TL2575
(ADJ)
OUTPUT
2
7-V to 40-V
Unregulated
DC Input
L1
VOUT
330 µH
R2
+
CIN
100 µF
3 GND
5
ON/OFF
D1
11DQ06
+
L
O
A
D
COUT
330 µF
R1
VOUT = VREF(1 + R2/R1) = 5 V
VREF = 1.23 V
R1 = 2 k
R2 = 6.12 k
A.
Pin numbers are for the KTT (TO-263) package.
Figure 2. Test Circuits and Layout Guidelines
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TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
TYPICAL CHARACTERISTICS
1
Output Voltage Change – %
0.6
0.2
0
-0.2
-0.4
-0.6
0.6
0.4
0.2
0
-0.2
-0.6
-25
0
25
50
75
100
125
0
150
20
30
40
50
VIN – Input Voltage – V
Figure 3. Normalized Output Voltage
Figure 4. Line Regulation
60
3
DVOUT = 5%
RIND = 0.2 W
2.5
IO – Output Current – A
1.5
ILOAD = 1 A
1.25
1
0.75
ILOAD = 200 mA
0.5
0.25
2
1.5
1
0.5
0
-40 -25 -10
5
20
35 50
65 80 95 110 125
TJ – Junction Temperature – °C
0
-50
Figure 5. Dropout Voltage
10
10
TA – Temperature – °C
2
Input-Output Differential – V
0.8
-0.4
-0.8
1.75
TJ = 25°C
1
TJ = 25°C
0.4
-1
-50
ILOAD = 200 mA
1.2
ILOAD = 200 mA
Output Voltage Change – %
0.8
1.4
VIN = 20 V
-25
0
25
50
75
100
TJ – Junction Temperature – °C
Figure 6. Current Limit
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125
150
TL2575, TL2575HV
1-A SIMPLE STEP-DOWN SWITCHING VOLTAGE REGULATORS
www.ti.com
SLVS638 – MAY 2006
TYPICAL CHARACTERISTICS (continued)
20
500
IQ – Quiescent Current – mA
ISTBY – Standby Quiescent Current – µA
VOUT = 5 V
18
TJ = 25°C
Measured at GND pin
16
14
12
10
ILOAD = 1 A
8
6
ILOAD = 0.2 A
4
2
0
0
10
20
40
50
350
300
250
200
150
100
VIN = 12 V
50
0
-50
60
-25
0
25
50
75
100
125
TJ – Junction Temperature – °C
Figure 7. Quiescent Current
Figure 8. Standby Quiescent Current
150
1.2
Normalized at TJ = 25°C
8
1.1
6
VSAT – Saturation Voltage – V
VIN = 12 V
4
2
0
VIN = 40 V
400
VIN – Input Voltage – V
10
f NORM – Normalized Frequency – %
30
VON/OFF = 5 V
450
VIN = 40 V
-2
-4
-6
-8
-10
-50
1
TJ = –40°C
0.9
0.8
TJ = 25°C
0.7
0.6
TJ = 125°C
0.5
-25
0
25
50
75
100
125
150
0.4
0
TJ – Junction Temperature – °C
Figure 9. Oscillator Frequency
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0.2
0.4
0.6
0.8
1
ISW – Switch Current – A
Figure 10. Switch Saturation Voltage
11
TL2575, TL2575HV
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TYPICAL CHARACTERISTICS (continued)
5
4.5
100
Adjustable version only
90
80
IIB – Feedback Bias Current – nA
VIN – Input Voltage – V
4
3.5
3
2.5
2
1.5
1
0.5
0
-50
-25
0
25
50
75
100
125
70
60
50
40
30
20
10
0
-10
-20
-30
-40
-50
-50
150
Adjustable version only
-25
0
25
50
75
100
TJ – Junction Temperature – °C
TJ – Junction Temperature – °C
Figure 11. Minimum Operating Voltage
Figure 12. FEEDBACK Current
125
150
VOUT = 5 V
A
B
C
{
0V
{
0A
{
0A
{
4 µs/Div
A.
Output pin voltage, 10 V/Div
B.
Output pin current, 1 A/Div
C.
Inductor current, 0.5 A/Div
D.
Ouput ripple voltage, 20 mV/Div
Figure 13. Switching Waveforms
12
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TYPICAL CHARACTERISTICS (continued)
0.2
ILOAD – Load Current – A
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.5
0.6
0.7
0.8
0.9
t – Time – ms
1.6
1.4
ILOAD – Load Current – A
1.2
1
0.8
0.6
0.4
0.2
0
-0.1
0
0.1
0.2
0.3
0.4
t – Time – ms
Figure 14. Load Transient Response
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APPLICATION INFORMATION
Input Capacitor (CIN)
For stability concerns, an input bypass capacitor (electrolytic, CIN ≥ 47 µF) needs to be located as close as
possible to the regulator. For operating temperatures below –25°C, CIN may need to be larger in value. In
addition, since most electrolytic capacitors have decreasing capacitances and increasing ESR as temperature
drops, adding a ceramic or solid tantalum capacitor in parallel increases the stability in cold temperatures.
To extend the capacitor operating lifetime, the capacitor RMS ripple current rating should be:
IC,RMS > 1.2(ton/T)ILOAD
where
ton/T = VOUT/VIN {buck regulator} and
ton/T = |VOUT|/(|VOUT| + VIN) {buck-boost regulator}
Output Capacitor (COUT)
For both loop stability and filtering of ripple voltage, an output capacitor also is required, again in close proximity
to the regulator. For best performance, low-ESR aluminum electrolytics are recommended, although standard
aluminum electrolytics may be adequate for some applications. Based on the following equation:
Output ripple voltage = (ESR of COUT) × (inductor ripple current)
Output ripple of 50 mV to 150 mV typically can be achieved with capacitor values of 220 µF to 680 µF. Larger
COUT can reduce the ripple 20 mV to 50 mV peak to peak. To improve further on output ripple, paralleling of
standard electrolytic capacitors may be used. Alternatively, higher-grade capacitors such as high frequency, low
inductance, or low ESR can be used.
The following should be taken into account when selecting COUT:
• At cold temperatures, the ESR of the electrolytic capacitors can rise dramatically (typically 3× nominal value
at –25°C). Because solid tantalum capacitors have significantly better ESR specifications at cold
temperatures, they should be used at operating temperature lower than –25°C. As an alternative, tantalums
also can be paralleled to aluminum electrolytics and should contribute 10% to 20% to the total capacitance.
• Low ESR for COUT is desirable for low output ripple. However, the ESR should be greater than 0.05 Ω to
avoid the possibility of regulator instability. Hence, a sole tantalum capacitor used for COUT is most
susceptible to this occurrence.
• The capacitor’s ripple current rating of 52 kHz should be at least 50% higher than the peak-to-peak inductor
ripple current.
Catch Diode
As with other external components, the catch diode should be placed close to the output to minimize unwanted
noise. Schottky diodes have fast switching speeds and low forward voltage drops and, thus, offer the best
performance, especially for switching regulators with low output voltages (VOUT < 5 V). If a high-efficiency,
fast-recovery, or ultra-fast-recovery diode is used in place of a Schottky, it should have a soft recovery (versus
abrupt turn-off characteristics) to avoid the chance of causing instability and EMI. Standard 50-/60-Hz diodes,
such as the 1N4001 or 1N5400 series, are not suitable.
14
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APPLICATION INFORMATION (continued)
Inductor
Proper inductor selection is key to the performance-switching power-supply designs. One important factor to
consider is whether the regulator is used in continuous mode (inductor current flows continuously and never
drops to zero) or in discontinuous mode (inductor current goes to zero during the normal switching cycle). Each
mode has distinctively different operating characteristics and, therefore, can affect the regulator performance
and requirements. In many applications, the continuous mode is the preferred mode of operation, since it offers
greater output power with lower peak currents, and also can result in lower output ripple voltage. The
advantages of continuous mode of operation come at the expense of a larger inductor required to keep inductor
current continuous, especially at low output currents and/or high input voltages.
The TL2575 and TL2575HV can operate in either continuous or discontinuous mode. With heavy load currents,
the inductor current flows continuously and the regulator operates in continuous mode. Under light load, the
inductor fully discharges and the regulator is forced into the discontinuous mode of operation. For light loads
(approximately 200 mA or less), this discontinuous mode of operation is perfectly acceptable and may be
desirable solely to keep the inductor value and size small. Any buck regulator eventually operates in
discontinuous mode when the load current is light enough.
The type of inductor chosen can have advantages and disadvantages. If high performance/quality is a concern,
then more-expensive toroid core inductors are the best choice, as the magnetic flux is contained completely
within the core, resulting in less EMI and noise in nearby sensitive circuits. Inexpensive bobbin core inductors,
however, generate more EMI as the open core does not confine the flux within the core. Multiple switching
regulators located in proximity to each other are particularly susceptible to mutual coupling of magnetic fluxes
from each other’s open cores. In these situations, closed magnetic structures (such as a toroid, pot core, or
E-core) are more appropriate.
Regardless of the type and value of inductor used, the inductor never should carry more than its rated current.
Doing so may cause the inductor to saturate, in which case the inductance quickly drops, and the inductor looks
like a low-value resistor (from the dc resistance of the windings). As a result, switching current rises dramatically
(until limited by the current-by-current limiting feature of the TL2575 and TL2575HV) and can result in
overheating of the inductor and the IC itself. Note that different types of inductors have different saturation
characteristics.
Output Voltage Ripple and Transients
As with any switching power supply, the output of the TL2575 and TL2575HV have a sawtooth ripple voltage at
the switching frequency. Typically about 1% of the output voltage, this ripple is due mainly to the inductor
sawtooth ripple current and the ESR of the output capacitor (see note on COUT). Furthermore, the output also
may contain small voltage spikes at the peaks of the sawtooth waveform. This is due to the fast switching of the
output switch and the parasitic inductance of COUT. These voltage spikes can be minimized through the use of
low-inductance capacitors.
There are several ways to reduce the output ripple voltage: a larger inductor, a larger COUT, or both. Another
method is to use a small LC filter (20 µH and 100 µF) at the output. This filter can reduce the output ripple
voltage by a factor of 10 (see Figure 2).
Feedback Connection
For fixed-voltage options, FEEDBACK must be wired to VOUT. For the adjustable version, FEEDBACK must be
connected between the two programming resistors. Again, both of these resistors should be in close proximity to
the regulator, and each should be less than 100 kΩ to minimize noise pickup.
ON/OFF Input
ON/OFF should be grounded or be a low-level TTL voltage (typically <1.6 V) for normal operation. To shut down
the TL2575 or TL2575HV and put it in standby mode, a high-level TTL or CMOS voltage should be supplied to
this pin. ON/OFF should not be left open and safely can be pulled up to VIN with or without a pullup resistor.
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APPLICATION INFORMATION (continued)
Grounding
The power and ground connections of the TL2575 and TL2575HV must be low impedance to help maintain
output stability. For the 5-pin packages, both pin 3 and tab are ground, and either connection can be used as
they are both part of the same lead frame. With the 16-pin package, all the ground pins (including signal and
power grounds) should be soldered directly to wide PCB copper traces to ensure low-inductance connections
and good thermal dissipation.
Layout Guidelines
With any switching regulator, circuit layout plays an important role in circuit performance. Wiring and parasitic
inductances, as well as stray capacitances, are subjected to rapidly switching currents, which can result in
unwanted voltage transients. To minimize inductance and ground loops, the length of the leads indicated by
heavy lines should be minimized. Optimal results can be achieved by single-point grounding (see Figure 2) or by
ground-plane construction. For the same reasons, the two programming resistors used in the adjustable version
should be located as close as possible to the regulator to keep the sensitive feedback wiring short.
16
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SLVS638 – MAY 2006
BUCK REGULATOR DESIGN PROCEDURE
PROCEDURE (Fixed Output)
EXAMPLE (Fixed Output)
Known:
VOUT = 3.3 V, 5 V, 12 V, or 15 V
VIN(Max) = Maximum input voltage
ILOAD(Max) = Maximum load current
Known:
VOUT = 5 V
VIN(Max) = 20 V
ILOAD(Max) = 1 A
1. Inductor Selection (L1)
1. Inductor Selection (L1)
A. From Figure 15 through Figure 18, select the appropriate inductor A. From Figure 16 (TL2575-05), the intersection of 20-V line and
code based on the intersection of VIN(Max) and ILOAD(Max).
1-A line gives an inductor code of L330.
B. From Table 2, choose the appropriate inductor based on the
inductor code. Parts from three well-known inductor manufacturers
are given. The inductor chosen should be rated for operation at
52-kHz and have a current rating of at least 1.15 × ILOAD(Max) to
allow for the ripple current. The actual peak current in L1 (in normal
operation) can be calculated as follows:
IL1(pk) = ILOAD(Max) + (VIN – VOUT) × ton/2L1
Where ton = VOUT/VIN× (1/fosc)
B. L330 → L1 = 330 µH
Choose from:
34042 (Schott)
PE-52627 (Pulse Engineering)
RL1952 (Renco)
2. Output Capacitor Selection (COUT)
2. Output Capacitor Selection (COUT)
A. The TL2575 control loop has a two-pole two-zero frequency
A. COUT = 100-µF to 470-µF, standard aluminum electrolytic
response. The dominant pole-zero pair is established by COUT and
L1. To meet stability requirements while maintaining an acceptable
output ripple voltage (Vripple ≈ 0.01 × VOUT), the recommended range
for a standard aluminum electrolytic COUT is between 100 µF and
470 µF.
B. COUT should have a voltage rating of at least 1.5 × VOUT. But if a
low output ripple voltage is desired, choose capacitors with a
higher-voltage ratings than the minimum required, due to their
typically lower ESRs.
B. Although a COUT rated at 8 V is sufficient for VOUT = 5 V, a
higher-voltage capacitor is chosen for its typically lower ESR (and
hence lower output ripple voltage) → Capacitor voltage
rating = 20 V.
3. Catch Diode Selection (D1) (see Table 1)
3. Catch Diode Selection (D1) (see Table 1)
A. In normal operation, the catch diode requires a current rating of
A. Pick a diode with 3-A rating.
at least 1.2 × ILOAD(Max). For the most robust design, D1 should be
rated to handle a current equal to the TL2575 maximum switch peak
current; this represents the worst-case scenario of a continuous
short at VOUT.
B. The diode requires a reverse voltage rating of at least
1.25 × VIN(Max).
B. Pick 30-V rated Schottky diode (1N5821, MBR330, 31QD03, or
SR303) or 100-V rated Fast Recovery diode (31DF1, MURD310, or
HER302).
4. Input Capacitor (CIN)
An aluminum electrolytic or tantalum capacitor is needed for input
bypassing. Locate CIN as close to the VIN and GND pins as
possible.
4. Input Capacitor (CIN)
CIN = 100 µF, 25 V, aluminum electrolytic
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SLVS638 – MAY 2006
PROCEDURE (Adjustable Output)
EXAMPLE (Adjustable Output)
Known:
VOUT(Nom)
VIN(Max) = Maximum input voltage
ILOAD(Max) = Maximum load current
Known:
VOUT = 10 V
VIN(Max) = 25 V
ILOAD(Max) = 1 A
1. Programming Output Voltage (Selecting R1 and R2)
Referring to Fig. 2, VOUT is defined by:
VOUT = VREF 1 + R2
where VREF = 1.23 V
R1
1. Programming Output Voltage (Selecting R1 and R2)
Select R1 = 1 kΩ
R2 = 1 (10/1.23 – 1) = 7.13 kΩ
Select R2 = 7.15 kΩ (closest 1% value)
(
(
Choose a value for R1 between 1 kΩ and 5 kΩ (use 1% metal-film
resistors for best temperature coefficient and stability over time).
VOUT
–1
R2 = R1
VREF
(
(
2. Inductor Selection (L1)
2. Inductor Selection (L1)
A. Calculate the "set" volts-second (E•T) across L1:
E•T = (VIN – VOUT) × ton
E•T = (VIN – VOUT) × (VOUT/VIN) × {1000/fosc(in kHz)} [V•µs]
NOTE: Along with ILOAD, the "set" volts-second (E•T) constant
establishes the minimum energy storage requirement for the
inductor.
A. Calculate the "set" volts-second (E•T) across L1:
E•T = (25 – 10) × (10/25) × (1000/52) [V•µs]
E•T = 115 V•µs
B. Using Figure 19, select the appropriate inductor code based on
the intersection of E•T value and ILOAD(Max).
B. Using Figure 19, the intersection of 115 V•µs and 1 A
corresponds to an inductor code of H470.
C. From Table 2, choose the appropriate inductor based on the
inductor code. Parts from three well-known inductor manufacturers
are given. The inductor chosen should be rated for operation at
52-kHz and have a current rating of at least 1.15 x ILOAD(Max) to
allow for the ripple current. The actual peak current in L1 (in normal
operation) can be calculated as follows:
IL1(pk) = ILOAD(Max) + (VIN – VOUT) × ton/2L1
Where ton = VOUT/VIN × (1/fosc)
C. H470 → L1 = 470 µF
Choose from:
34048 (Schott)
PE-53118 (Pulse Engineering)
RL1961 (Renco)
3. Output Capacitor Selection (COUT)
3. Output Capacitor Selection (COUT)
A. The TL2575 control loop has a two-pole two-zero frequency
response. The dominant pole-zero pair is established by COUT and
L1. To meet stability requirements, COUT must meet the following
requirement:
VIN(Max)
(µF)
COUT ³ 7758
VOUT · L1(µH)
A.COUT ≥ 7785 × 25/(10 × 470) [µF]
COUT ≥ 41.4 µF
To obtain an acceptable output voltage ripple →
COUT = 220 µF electrolytic
However, COUT may need to be several times larger than the
calculated value above in order to achieve an acceptable output
ripple voltage of ~0.01 × VOUT.
B. COUT should have a voltage rating of at least 1.5 × VOUT. But if a
low output ripple voltage is desired, choose capacitors with a higher
voltage ratings than the minimum required due to their typically
lower ESRs.
4. Catch Diode Selection (D1) (see Table 1)
4. Catch Diode Selection (D1) (see Table 1)
A. In normal operation, the catch diode requires a current rating of
at least 1.2 × ILOAD(Max). For the most robust design, D1 should be
rated for a current equal to the TL2575 maximum switch peak
current; this represents the worst-case scenario of a continuous
short at VOUT.
A. Pick a diode with a 3-A rating.
B. The diode requires a reverse voltage rating of at least
1.25 × VIN(Max).
B. Pick a 40-V rated Schottky diode (1N5822, MBR340, 31QD04, or
SR304) or 100-V rated Fast Recovery diode (31DF1, MURD310, or
HER302)
5. Input Capacitor (CIN)
An aluminum electrolytic or tantalum capacitor is needed for input
bypassing. Locate CIN as close to VIN and GND pins as possible.
5. Input Capacitor (CIN)
CIN = 100 µF, 35 V, aluminum electrolytic
18
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SLVS638 – MAY 2006
Inductor Value Selection Guide for Continuous-Mode Operation
Figure 15. TL2575-33
Figure 16. TL2575-50
Figure 17. TL2575-12
Figure 18. TL2575-15
Figure 19. TL2575-ADJ
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SLVS638 – MAY 2006
Table 1. Diode Selection Guide
VR
SCHOTTKY
FAST RECOVERY
1A
3A
20 V
1N5817
MBR120P
SR102
1N5820
MBR320
SR302
30 V
1N5818
MBR130P
11DQ03
SR103
1N5821
MBR330
31DQ03
SR303
40 V
1N5819
MBR140P
11DQ04
SR104
IN5822
MBR340
31DQ04
SR304
50 V
MBR150
11DQ05
SR105
MBR350
31DQ05
SR305
60 V
MBR160
11DQ06
SR106
MBR360
31DQ06
SR306
1A
3A
The following diodes
The following diodes
are all rated to 100 V: are all rated to 100 V:
11DF1
31DF1
MUR110
MURD310
HER102
HER302
Table 2. Inductor Selection by Manufacturer's Part Number
(1)
(2)
(3)
20
INDUCTOR CODE
INDUCTOR VALUE
(µH)
SCHOTT
CORPORATION (1)
PULSE ENGINEERING (2)
RENCO
ELECTRONICS (3)
L100
100
67127000
PE-92108
RL2444
L150
150
67127010
PE-53113
RL1954
L220
220
67127020
PE-52626
RL1953
L330
330
67127030
PE-52627
RL1952
L470
470
67127040
PE-53114
RL1951
L680
680
67127050
PE-52629
RL1950
H150
150
67127060
PE-53115
RL2445
H220
220
67127070
PE-53116
RL2446
H330
330
67127080
PE-53117
RL2447
H470
470
67127090
PE-53118
RL1961
H680
680
67127100
PE-53119
RL1960
H1000
1000
67127110
PE-53120
RL1959
H1500
1500
67127120
PE-53121
RL1958
H2200
2200
67127130
PE-53122
RL2448
Schott Corporation, (612) 475-1173, 1000 Parkers Lake Rd., Wayzata, MN 55391
Pulse Engineering, (619) 674-8100, P.O. Box 12236, San Diego, CA 92112
Renco Electronics Inc., (516) 586-5566, 60 Jeffryn Blvd. East, Deer Park, NY 11729
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PACKAGE OPTION ADDENDUM
www.ti.com
18-May-2006
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
TL2575-05IN
ACTIVE
PDIP
N
16
25
Pb-Free
(RoHS)
CU NIPD
N / A for Pkg Type
TL2575-33IN
ACTIVE
PDIP
N
16
25
Pb-Free
(RoHS)
CU NIPD
N / A for Pkg Type
Lead/Ball Finish
MSL Peak Temp (3)
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
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