L5970D
Up to 1A step down switching regulator
Features
■
■
■
■
■
■
■
■
■
■
■
■
■
Up to 1A output current
Operating input voltage from 4.4V to 36V
3.3V / (±2%) reference voltage
Output voltage adjustable from 1.2V to 35V
Low dropout operation: 100% duty cycle
250KHz Internally fixed frequency
Voltage feedforward
Zero load current operation
Internal current limiting
Inhibit for zero current consumption
Synchronization
Protection against feedback disconnection
Thermal shutdown
Applications
■
■
■
■
Consumer: STB, DVD, TV, VCR, car radio,
LCD monitors
Networking: XDSL, modems, DC-DC modules
Computer: printers, audio/graphic cards, optical storage, hard disk drive
Industrial: changers, car battery, DC-DC converters
Description
SO8
The L5970D is a step down monolithic power switching regulator capable to deliver up to 1A at output voltages from 1.2V to 35V.
The device uses an internal P-Channel D-MOS transistor (with a typical Rdson of 250m
Ω) as switching element to minimize the size of the external components.
An internal oscillator fixes the switching frequency at 250KHz.
Having a minimum input voltage of 4.4V only, it is particularly suitable for 5V bus, available in all computer related applications.
Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection.
Figure 1.
Test application circuit
VIN = 4.4V to 35V
C1
10
µF
35V
CERAMIC
3.3V
VREF
6
1
VCC
8
L5970D
SYNC.
2
C4
22nF
C3
220pF
COMP
R3
4.7K
4
INH.
3 7
GND
5
OUT
FB
L1 33
µH
D1
STPS2L40U
R1
5.6K
VOUT=3.3V
C2
100
µF
10V
R2
3.3K
October 2007 Rev 16
D98IN954C
1/16
www.st.com
16
7
8
9
5
6
3
4
Contents
Contents
1
2
L5970D
Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1
Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2/16
L5970D Pin settings
Figure 2.
Pin connection (top view)
OUT
SYNC
INH
COMP
1
2
3
4
D98IN955
6
5
8
7
VCC
GND
VREF
FB
Table 1. Pin description
N° Type
1 OUT Regulator output.
2 SYNC
3
4
5
6
7
8
INH
COMP
FB
VREF
GND
VCC
Description
Master/slave synchronization.
A logical signal (active high) disables the device. If INH not used the pin must be grounded. When it is open an internal pull-up disable the device.
E/A output for frequency compensation.
Feedback input. Connecting directly to this pin results in an output voltage of 1.23V. An external resistive divider is required for higher output voltages.
3.3V V
REF
. No cap is requested for stability.
Ground.
Unregulated DC input voltage.
3/16
Electrical data L5970D
Table 2. Absolute maximum ratings
Symbol Parameter
Input voltage V
8
V
1
Output DC voltage
Output peak voltage at t = 0.1
µs
Maximum output current I
1
V
4
, V
5
V
3
V
2
P
TOT
T
J
T
STG
Analog pins
INH
SYNC
Power dissipation at T
A
≤ 60°C
Operating junction temperature range
Storage temperature range
Table 3. Thermal data
Symbol Parameter
R thJA
Maximum thermal resistance junction-ambient
1.
Package mounted on board
Value
40
-1 to 40
-5 to 40 int. limit.
4
-0.3V to V
CC
-0.3 to 4
0.75
-40 to 150
-55 to 150
Unit
V
V
V
V
V
W
°C
°C
SO8
120
(1)
Unit
°C/W
4/16
L5970D Electrical characteristics
Table 4. Electrical characteristics
( T
J
= 25°C, V
CC
= 12V, unless otherwise specified)
Symbol Parameter Test condition
V
CC
R
DS(on)
I l
Operating input voltage range
Mosfet on
Resistance
Maximum limiting current
V o
= 1.235V; I o
= 2A
V
CC
= 4.4V to 36V
(1)
(1)
(1) f s
Switching frequency
Duty cycle
Dynamic characteristics (see test circuit ).
V
5
Voltage feedback
4.4V < V
CC
< 36V,
20mA < I
O
< 2A
V
O
= 5V, V
CC
= 12V h Efficiency
DC characteristics
I qop
Total operating quiescent current
I
I q qst-by
Quiescent current
Total stand-by quiescent current
Duty cycle = 0;
V
FB
= 1.5V
V inh
> 2.2V
V
CC
= 36V;
V inh
> 2.2V
Inhibit
INH threshold voltage
Device ON
Device OFF
Error amplfier
I
V
V
OH
OL o source
High level output voltage
Low level output voltage
Source output current
V
V
FB
FB
V
FB
= 1V
= 1.5V
V
COMP
= 1.9V;
= 1V
(1)
(1)
(1)
Min
4.4
Typ Max Unit
36 V
0.250
0.5
Ω
1.5
212
225
0
1.87
2.25
250 280
250 275
100
A
KHz
KHz
%
(1)
1.220
1.235
1.25
1.198
1.235
1.272
90
V
V
%
2.2
3.5
3
50
80
200 300
5
2.5
100
150
0.8
0.4
mA mA
µA
µA
V
V
V
V
µA
5/16
Electrical characteristics L5970D
Table 4. Electrical characteristics (continued)
( T
J
= 25°C, V
CC
= 12V, unless otherwise specified)
Symbol Parameter Test condition
I o sink
Sink output current
V
COMP
= 1.9V;
V
FB
= 1.5V
I b gm
Source bias current
DC open loop gain
R
L
=
∞
Transconductance
I comp
= -0.1mA to
0.1mA
V
COMP
= 1.9V
Sync function
High input voltage
Low input voltage
Slave sink current
V
CC
= 4.4V to 36V
V
CC
= 4.4V to 36V
V sync
= 0.74V
(2)
V sync
= 2.33V
Master output amplitude
I source
= 3mA
Output pulse width no load,
V sync
= 1.65V
Reference section
Min
1
50
2.5
0.11
0.21
2.75
Typ Max Unit
1.5
2.5
65
2.3
3
0.20
0.35
4
V
REF
0.74
0.25
0.45
mA
µA dB mS
V
µs
Reference voltage
Line regulation
I
REF
= 0 to 5mA
V
CC
= 4.4V to 36V
I
REF
= 0mA
V
CC
= 4.4V to 36V
I
REF
= 0 to 5mA
(1)
3.234
3.3
3.366
3.2
3.3
5
3.399
10
V
V mV
Load regulation
Short circuit current 10
8
18
15
30 mV mA
1.
Specification Referred to T
J
from -40 to 125°C. Specification over the -40 to +125 T
J
Temperature range are assured by design, characterization and statistical correlation.
2.
Guaranteed by design.
V
V mA mA
6/16
L5970D Typical characteristics
Figure 3.
Junction temperature vs output current
Tj(°C)
80
70
60
50
40
30
20
130
120
110
100
90
Vcc=5V
Tamb=25°C
0.2
0.4
0.6
0.8
Io(A)
1
Vo=3.3V
Vo=2.5V
Vo=1.8V
1.2
1.4
1.6
Figure 4.
Load regulator
Vo (V)
3.312
3.308
3.304
3.3
3.296
3.292
3.288
3.284
3.28
3.276
0
Vcc = 12V
Vo = 3.3V
0.5
Tj = 25°C
Tj = 125°C
Io (A)
1 1.5
Figure 5.
Junction temperature vs output current
Tj(°C)
130
120
110
100
90
80
70
60
50
40
30
20
0.2
Vcc=12V
Tamb=25°C
0.4
0.6
0.8
Io(A)
1
Vo=5V
1.2
Vo=3.3V
Vo=2.5V
1.4
1.6
Figure 6.
Line regulator
Vo (V)
3.312
3.308
3.304
3.3
3.296
3.292
3.288
3.284
3.28
3.276
0
Vcc = 12V
Vo = 3.3V
10
Tj = 25°C
Tj = 125°C
20
Vcc (V)
30
Figure 7.
Junction temperature vs output current
Tj(°C)
140
120
100
80
60
Vcc=24V
Tamb=25°C
40
20
0
0.2
0.4
0.6
Vo=18V
0.8
Io(A)
Vo=5V
1
Vo=12V
1.2
1.4
Figure 8.
Output voltage vs junction temperature
Vo (V)
1.25
1.24
1.23
1.22
1.21
1.2
-50 0 50
Tj (°C)
Vcc = 12V
Vcc=12V
100
40
150
7/16
Typical characteristics L5970D
Figure 9.
Quiescent current vs junction temperature
Iq (mA)
2
Figure 10. Switching frequency vs junction temperature
Fsw (KHz)
260
1.8
250
1.6
1.4
Vcc = 12V
DC = 0%
240
230
Vcc = 12V
Vo = 3.3V
1.2
-50
0 50
Tj (°C)
100 150
220
-50 0 50
Tj (C)
100 150
Figure 11. Shutdown current vs junction temperature
Ishd (
µA)
70
Figure 12. Efficiency vs output current
60
50
40
30
-50
Vcc = 12V
0
50
Tj (°C)
100 150
94
92
90
88
86
84
Vo=3.3V
Vo=2.5V
82
80
78
Vo=1.8V
76
74
72
Vcc=5V
70
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Io (A)
Figure 13. Efficiency vs output current
92
90
88
86
84
82
Vo=5V
Vo=3.3V
80
78 Vo=2.5V
76
74
72
Vcc=12V
70
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Io (A)
8/16
L5970D Application circuit
Figure 14. Demo board application circuit
VIN = 4.4V to 25V
C1
10
µF
25V
CERAMIC
3.3V
VREF
6
1
VCC
SYNC.
8
2
L5970D
C4
22nF
C3
220pF
COMP
R3
4.7K
4
INH.
3 7
GND
5
OUT
FB
L1 33
µH
D1
STPS2L25U
R1
5.6K
VOUT=3.3V
C2
100
µF
10V
R2
3.3K
D03IN1437
C4
R1
R2
R3
D1
L1
Table 5. Component list
C1
C2
Reference Part number Description
GRM32DR61E106KA12L 10
µF, 25V
POSCAP 10TPB100M 100
µF, 10V
C3 C1206C221J5GAC 220pF, 5%, 50V
C1206C223K5RAC
STPS2L25U
DO3316P-333
22nF, 10%, 50V
5.6K, 1%, 0.1W 0603
3.3K, 1%, 0.1W 0603
4.7K, 1%, 0.1W 0603
2A, 25V
33
µH, 2A
Manufacturer
MURATA
Sanyo
KEMET
KEMET
Neohm
Neohm
Neohm
STMicroelectronics
COILCRAFT
9/16
Application circuit
Figure 15. PCB layout (component side)
L5970D
Figure 16. PCB layout (bottom side)
Figure 17. PCB layout (front side)
10/16
L5970D Application ideas
Figure 18. Dual output voltage with auxiliary winding
N1/N2=2
D2
1N4148
VIN=12V
C1
10uF
25V
Ceramic
C2
220pF
VCC
8
C3
22nF
R3
4.7k
COMP
4
2
SYNC VREF
U1
L5970D
6
GND
3.3V
7
1
OUT
3
5
INH
FB
D1
STPS25L25U
Lp=22uH
VOUT1=5V
30mA
C4
100uF
10V
VOUT=3.3V
0.5A
C5
47uF
10V
Figure 19. Buck-boost regulator
L1
33uH
VIN=12V
C1
10uF
25V
Ceramic
C2
10uF
35V
Ceramic
C3
220pF
VCC
8
C4
22nF
R3
4.7k
U1
L5970
COMP
4
2
SYNC VREF
6
GND
7
3.3V
1
OUT
3
5
INH
FB
2.7k
24k
D1
STPS2L25U
C5
100uF
16V
VOUT=-12V/0.3A
Vin=12V Vout=-12V Iout=0.5A Efficiency=81%
Figure 20. Positive Buck-Boost regulator
VIN=5V
C1
10uF
25V
Ceramic
C2
220pF
VCC
8
C3
22nF
R3
4.7k
COMP
U1
L5970
4
2
SYNC VREF
6
GND
3.3V
7
1
OUT
3
5
INH
FB
D1
STPS2L25U
L1
33uH
D2
STPS2L25U
VOUT=12V/0.3A
M1
STN4NE03L
24k
2.7k
C4
100uF
16V
Vin=5V Vout=12V Iout=0.3A Efficiency=76%
Figure 21. Synchronization example
VIN
VCC
8
L5970D
COMP
4
2
SYNC VREF
6
GND
7 3
5
1
OUT
INH
FB
VCC
8
1
OUT
L5970D
COMP
4
2
SYNC VREF
6
GND
7 3
5
INH
FB
11/16
Package mechanical data
7 Package mechanical data
L5970D
In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect . The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
12/16
L5970D Package mechanical data
Table 6. SO-8 mechanical data mm.
Dim.
Min Typ
A 1.35
Max Min
A1 0.10
A2 1.10
B 0.33
C 0.19
D
(1)
E 3.80 e 1.27
H 5.80 h 0.25
L 0.40 k 0° (min.), 8° (max.)
inch
Typ Max
0.069
0.010
0.065
0.020
0.010
0.157
0.050
0.244
0.020
0.050
1.
Dimensions D does not include mold flash, protru-sions or gate burrs. Mold flash, potrusions or gate burrs shall not exceed 0.15mm (.006inch) in total (both side).
Figure 22. Package dimensions
13/16
Order codes
Table 7. Order codes
Part number
L5970D
L5970D013TR
Package Packaging
SO8 Tube
L5970D
14/16
L5970D
Table 8. Revision history
Date Revision
26-Jan-2007 14
16-Mar-2007
16-Oct-2007
15
16
Changes
Updated
Table 5 on page 9
Mechanical data typo
Updated
Section 5: Application circuit on page 9
Revision history
15/16
L5970D
Please Read Carefully:
Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice.
All ST products are sold pursuant to ST’s terms and conditions of sale.
Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.
UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED
WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS
OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT
RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING
APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY,
DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE
GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK.
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any liability of ST.
ST and the ST logo are trademarks or registered trademarks of ST in various countries.
Information in this document supersedes and replaces all information previously supplied.
The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.
© 2007 STMicroelectronics - All rights reserved
STMicroelectronics group of companies
Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan -
Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America
www.st.com
16/16
