STMicroelectronics E-L5970D Up to 1a step down switching regulator Datasheet

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
Description
■
Voltage feedforward
■
Zero load current operation
■
Internal current limiting
The L5970D is a step down monolithic power
switching regulator capable to deliver up to 1A at
output voltages from 1.2V to 35V.
■
Inhibit for zero current consumption
■
Synchronization
■
Protection against feedback disconnection
■
Thermal shutdown
SO8
The device uses an internal P-Channel D-MOS
transistor (with a typical Rdson of 250mΩ) as
switching element to minimize the size of the
external components.
An internal oscillator fixes the switching frequency
at 250KHz.
Applications
Having a minimum input voltage of 4.4V only, it is
particularly suitable for 5V bus, available in all
computer related 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
Figure 1.
Pulse by pulse current limit with the internal
frequency modulation offers an effective constant
current short circuit protection.
Test application circuit
VREF
3.3V
VIN = 4.4V to 35V
VCC
SYNC.
C1
10µF
35V
CERAMIC
COMP
C4
22nF
C3
220pF
6
1
8
OUT
D1
STPS2L40U
L5970D
2
3
4
INH.
L1 33µH
5
7
FB
GND
R3
4.7K
VOUT=3.3V
R1
5.6K
C2
100µF
10V
R2
3.3K
D98IN954C
October 2007
Rev 16
1/16
www.st.com
16
Contents
L5970D
Contents
1
2
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
3
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6
Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8
Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2/16
L5970D
Pin settings
1
Pin settings
1.1
Pin connection
Figure 2.
Pin connection (top view)
OUT
1
8
VCC
SYNC
2
7
GND
INH
3
6
VREF
COMP
4
5
FB
D98IN955
1.2
Pin description
Table 1. Pin description
N°
Type
Description
1
OUT
2
SYNC
3
INH
4
COMP
5
FB
6
VREF
3.3V VREF. No cap is requested for stability.
7
GND
Ground.
8
VCC
Unregulated DC input voltage.
Regulator output.
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.
3/16
Electrical data
L5970D
2
Electrical data
2.1
Maximum ratings
Table 2. Absolute maximum ratings
Symbol
Value
Unit
40
V
V
V
V8
Input voltage
V1
Output DC voltage
Output peak voltage at t = 0.1µs
-1 to 40
-5 to 40
I1
Maximum output current
int. limit.
V4, V5
Analog pins
V3
INH
V2
SYNC
PTOT
TJ
TSTG
2.2
Parameter
4
V
-0.3V to VCC
-0.3 to 4
V
0.75
W
Operating junction temperature range
-40 to 150
°C
Storage temperature range
-55 to 150
°C
SO8
Unit
120 (1)
°C/W
Power dissipation at TA ≤ 60°C
Thermal data
Table 3. Thermal data
Symbol
RthJA
Parameter
Maximum thermal resistance junction-ambient
1. Package mounted on board
4/16
L5970D
3
Electrical characteristics
Electrical characteristics
Table 4. Electrical characteristics
( TJ = 25°C, VCC = 12V, unless otherwise specified)
Symbol
VCC
RDS(on)
Parameter
Operating input
voltage range
Test condition
Vo = 1.235V; Io = 2A
Mosfet on
Resistance
Il
Maximum limiting
current
fs
Switching frequency
Min
(1)
Max
Unit
36
V
0.250
0.5
Ω
1.5
1.87
2.25
A
212
250
280
KHz
225
250
275
KHz
100
%
4.4
(1)
VCC = 4.4V to 36V
(1)
Duty cycle
Typ
0
Dynamic characteristics (see test circuit ).
V5
Voltage feedback
h
Efficiency
4.4V < VCC < 36V,
20mA < IO < 2A
(1)
1.220
1.235
1.25
V
1.198
1.235
1.272
V
VO = 5V, VCC = 12V
90
%
DC characteristics
Iqop
Total operating
quiescent current
Iq
Quiescent current
Iqst-by
Total stand-by
quiescent current
(1)
3
Duty cycle = 0;
VFB = 1.5V
5
mA
2.5
mA
Vinh > 2.2V
(1)
50
100
µA
VCC = 36V;
Vinh > 2.2V
(1)
80
150
µA
0.8
V
Inhibit
INH threshold
voltage
Device ON
Device OFF
2.2
V
3.5
V
Error amplfier
VOH
High level output
voltage
VFB = 1V
VOL
Low level output
voltage
VFB = 1.5V
Source output
current
VCOMP = 1.9V;
VFB = 1V
Io source
0.4
200
300
V
µA
5/16
Electrical characteristics
L5970D
Table 4. Electrical characteristics (continued)
( TJ = 25°C, VCC = 12V, unless otherwise specified)
Symbol
Parameter
Io sink
Sink output current
Ib
Source bias current
gm
Test condition
VCOMP = 1.9V;
VFB = 1.5V
Min
Typ
1
1.5
2.5
DC open loop gain
RL = ∞
Transconductance
Icomp = -0.1mA to
0.1mA
VCOMP = 1.9V
High input voltage
VCC = 4.4V to 36V
Low input voltage
VCC = 4.4V to 36V
Slave sink current
Vsync = 0.74V (2)
Vsync = 2.33V
Master output
amplitude
Isource = 3mA
Output pulse width
no load,
Vsync = 1.65V
50
Max
Unit
mA
4
µA
65
dB
2.3
mS
Sync function
2.5
0.11
0.21
VREF
V
0.74
V
0.25
0.45
mA
mA
2.75
3
V
0.20
0.35
µs
3.234
3.3
3.366
V
3.2
3.3
3.399
V
Reference section
Reference voltage
IREF = 0 to 5mA
VCC = 4.4V to 36V
(1)
Line regulation
IREF = 0mA
VCC = 4.4V to 36V
5
10
mV
Load regulation
IREF = 0 to 5mA
8
15
mV
18
30
mA
Short circuit current
10
1. Specification Referred to TJ from -40 to 125°C. Specification over the -40 to +125 TJ Temperature range
are assured by design, characterization and statistical correlation.
2. Guaranteed by design.
6/16
L5970D
4
Typical characteristics
Typical characteristics
Figure 3.
Junction temperature vs
output current
Figure 4.
Vo (V)
3.312
Tj(°C)
130
120
110
100
90
80
70
60
50
40
30
20
Vo=3.3V
Vcc=5V
Tamb=25°C
Vo=2.5V
Vo=1.8V
Load regulator
Vcc = 12V
Vo = 3.3V
3.308
3.304
Tj = 25°C
3.3
3.296
3.292
3.288
3.284
Tj = 125°C
3.28
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
3.276
0
0.5
Figure 5.
1
1.5
Io (A)
Io(A)
Junction temperature vs
output current
Figure 6.
Line regulator
Vo (V)
Tj(°C)
3.312
130
120
110
100
90
80
70
60
50
40
30
20
Vo=3.3V
Vo=5V
Vcc = 12V
Vo = 3.3V
3.308
3.304
Vo=2.5V
Vcc=12V
Tamb=25°C
Tj = 25°C
3.3
3.296
3.292
Tj = 125°C
3.288
3.284
3.28
3.276
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0
Io(A)
Figure 7.
Junction temperature vs
output current
Figure 8.
20
Vcc (V)
30
40
Output voltage vs junction
temperature
Vo (V)
1.25
Tj(°C)
140
Vo=18V
Vo=12V
1.24
120
100
10
Vo=5V
Vcc=24V
Tamb=25°C
1.23
80
1.22
60
Vcc = 12V
40
1.21
Vcc=12V
20
0
0.2
1.2
0.4
0.6
0.8
Io(A)
1
1.2
1.4
-50
0
50
Tj (°C)
100
150
7/16
Typical characteristics
L5970D
Figure 9.
Quiescent current vs
junction temperature
Figure 10. Switching frequency vs
junction temperature
Iq (mA)
2
Fsw (KHz)
260
1.8
250
1.6
240
Vcc = 12V
DC = 0%
1.4
Vcc = 12V
Vo = 3.3V
230
1.2
220
-50
0
50
Tj (°C)
100
150
-50
0
50
Tj (C)
100
150
Figure 11. Shutdown current vs junction Figure 12. Efficiency vs output current
temperature
Ishd (µA)
60
Efficiency (%)
70
Vcc = 12V
50
40
30
-50
50
Tj (°C)
0
100
150
Efficiency (%)
Figure 13. Efficiency vs output current
8/16
92
90
88
86
84
82
80
78
76
74
72
70
Vo=5V
Vo=3.3V
Vo=2.5V
Vcc=12V
0.1
0.2
0.3
0.4
0.5 0.6
Io (A)
0.7
0.8
0.9
1
94
92
90
88
86
84
82
80
78
76
74
72
70
0.1
Vo=3.3V
Vo=2.5V
Vo=1.8V
Vcc=5V
0.2
0.3
0.4
0.5 0.6
Io (A)
0.7
0.8
0.9
1
L5970D
5
Application circuit
Application circuit
Figure 14. Demo board application circuit
VREF
3.3V
VIN = 4.4V to 25V
VCC
SYNC.
C1
10µF
25V
CERAMIC
COMP
C4
22nF
C3
220pF
6
1
8
D1
STPS2L25U
L5970D
2
3
4
INH.
7
L1 33µH
OUT
5
FB
GND
VOUT=3.3V
R1
5.6K
C2
100µF
10V
R2
3.3K
R3
4.7K
D03IN1437
Table 5. Component list
Reference
Part number
Description
Manufacturer
C1
GRM32DR61E106KA12L
10µF, 25V
MURATA
C2
POSCAP 10TPB100M
100µF, 10V
Sanyo
C3
C1206C221J5GAC
220pF, 5%, 50V
KEMET
C4
C1206C223K5RAC
22nF, 10%, 50V
KEMET
R1
5.6K, 1%, 0.1W 0603
Neohm
R2
3.3K, 1%, 0.1W 0603
Neohm
R3
4.7K, 1%, 0.1W 0603
Neohm
D1
STPS2L25U
2A, 25V
STMicroelectronics
L1
DO3316P-333
33µH, 2A
COILCRAFT
9/16
Application circuit
Figure 15. PCB layout (component side)
Figure 16. PCB layout (bottom side)
Figure 17. PCB layout (front side)
10/16
L5970D
L5970D
6
Application ideas
Application ideas
Figure 18. Dual output voltage with auxiliary winding
N1/N2=2
VIN=12V
VCC
COMP
C1
10uF
25V
Ceramic
1
C3
22nF
R3
4.7k
FB
4
6
5
3
7
SYNC VREF
VOUT=3.3V
0.5A
D1
STPS25L25U
U1
L5970D
2
C2
220pF
VOUT1=5V
30mA
Lp=22uH
OUT
8
D2
1N4148
GND
C4
100uF
10V
C5
47uF
10V
INH
3.3V
Figure 19. Buck-boost regulator
VIN=12V
VCC
8
1
U1
C2
10uF
C3
35V
Ceramic 220pF
Vin=12V Vout=-12V
4
2
C4
22nF
R3
4.7k
D1
STPS2L25U
L5970
COMP
C1
10uF
25V
Ceramic
L1
33uH
OUT
6
5
3
7
SYNC VREF
GND
FB
INH
VOUT=-12V/0.3A
2.7k
C5
100uF
16V
24k
3.3V
Iout=0.5A Efficiency=81%
Figure 20. Positive Buck-Boost regulator
L1
33uH
VIN=5V
VCC
8
D1
STPS2L25U
L5970
4
2
C2
220pF
C3
22nF
R3
4.7k
6
7
24k
FB
5
3
GND
SYNC VREF
VOUT=12V/0.3A
1
U1
COMP
C1
10uF
25V
Ceramic
D2
STPS2L25U
OUT
C4
100uF
16V
M1
STN4NE03L
INH
2.7k
3.3V
Vin=5V Vout=12V Iout=0.3A Efficiency=76%
Figure 21. Synchronization example
VIN
OUT
VCC
8
COMP
L5970D
4
2
SYNC VREF
6
7
GND
5
3
OUT
VCC
8
1
FB
INH
COMP
1
L5970D
4
2
SYNC VREF
6
7
GND
5
3
FB
INH
11/16
Package mechanical data
7
L5970D
Package mechanical data
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.
inch
Dim.
Min
Typ
Max
Min
Typ
Max
A
1.35
1.75
0.053
0.069
A1
0.10
0.25
0.004
0.010
A2
1.10
1.65
0.043
0.065
B
0.33
0.51
0.013
0.020
C
0.19
0.25
0.007
0.010
(1)
4.80
5.00
0.189
0.197
E
3.80
4.00
0.15
0.157
D
e
1.27
0.050
H
5.80
6.20
0.228
0.244
h
0.25
0.50
0.010
0.020
L
0.40
1.27
0.016
0.050
k
ddd
0° (min.), 8° (max.)
0.10
0.004
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
8
L5970D
Order codes
Table 7. Order codes
14/16
Part number
Package
Packaging
L5970D
SO8
Tube
L5970D013TR
SO8
Tape and reel
L5970D
9
Revision history
Revision history
Table 8. Revision history
Date
Revision
Changes
26-Jan-2007
14
Updated Table 5 on page 9
16-Mar-2007
15
Mechanical data typo
16-Oct-2007
16
Updated Section 5: Application circuit on page 9
15/16
L5970D
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