L5973D
2.5 A switch step down switching regulator
Features
2.5 A internal switch Operating input voltage from 4 V to 36 V 3.3 V / (2%) reference voltage Output voltage adjustable from 1.235 V to 35 V Low dropout operation: 100 % duty cycle 250 kHz internally fixed frequency Voltage feedforward Zero load current operation Internal current limiting Inhibit for zero current consumption Synchronization Protection against feedback disconnection Thermal shutdown
HSOP8 exposed pad
Description
The L5973D is a step down monolithic power switching regulator with a minimum switch current limit of 2.5 A so it is able to deliver more than 2 A DC current to the load depending on the application conditions. The output voltage can be set from 1.235 V to 35 V. The high current level is also achieved thanks to an SO8 package with exposed frame, that allows to reduce the Rth(j-amb) down to approximately 40 C/W. The device uses an internal P-channel D-MOS transistor (with a typical Rdson of 250 m) as switching element to minimize the size of the external components. An internal oscillator fixes the switching frequency at 250 kHz. Having a minimum input voltage of 4 V only, it is particularly suitable for 5 V 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.
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.
Test application circuit
3.3V VIN = 4.4V to 35V VREF VCC SYNC. C1 10F 35V CERAMIC COMP C4 22nF C3 220pF R3 4.7K 6 8 2 4 INH 1 OUT L1 15H D1 STPS340U 5 FB GND R2 3.3K VOUT=3.3V
L5973D
3 7
R1 5.6K
C2 330F 10V
D03IN1439
January 2008
Rev 16
1/17
www.st.com 17
Contents
L5973D
Contents
1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 1.2 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 2.2 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 4 5 6 7 8 9
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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L5973D
Pin settings
1
1.1
Pin settings
Pin connection
Figure 2. Pin connection (top view)
OUT SYNC INH COMP
1 2 3 4
D98IN955
8 7 6 5
VCC GND VREF FB
1.2
Pin description
Table 1.
N 1 2 3 4 5 6 7 8
Pin description
Type OUT SYNC INH COMP FB VREF GND VCC 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 1.23 V. An external resistive divider is required for higher output voltages. 3.3 V VREF. No cap is requested for stability. Ground. Unregulated DC input voltage. Description
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Electrical data
L5973D
2
2.1
Electrical data
Maximum ratings
Table 2.
Symbol V8 V1 I1 V4, V5 V3 V2 PTOT TJ TSTG Input voltage Output DC voltage Output peak voltage at t = 0.1 s Maximum output current Analog pins INH SYNC Power dissipation at TA 60 C Operating junction temperature range Storage temperature range
Absolute maximum ratings
Parameter Value 40 -1 to 40 -5 to 40 int. limit. 4 -0.3 V to VCC -0.3 to 4 2.25 -40 to 150 -55 to 150 V W C C V Unit V V V
2.2
Thermal data
Table 3.
Symbol RthJA
Thermal data
Parameter Maximum thermal resistance junction-ambient HSOP8 Exposed Pad 40 (1) Unit C/W
1. Package mounted on board
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L5973D
Electrical characteristics
3
Electrical characteristics
Table 4.
Symbol VCC RDS(on) Il fs
Electrical characteristics ( TJ = 25 C, VCC = 12 V, unless otherwise specified)
Parameter Operating input voltage range Mosfet on Resistance Maximum limiting current Switching frequency 225 Duty cycle 0 250 275 100 kHz % VCC = 4.4 V to 36 V
(1)
Test condition Vo = 1.235 V; Io = 2 A
(1)
Min 4
Typ
Max 36
Unit V A kHz
(1)
0.250 2.5 212 3 250
0.5 3.5 280
Dynamic characteristics (see test circuit ). V5 h Voltage feedback Efficiency 4.4 V < VCC < 36 V, 20 mA < IO < 2 A VO = 5 V, VCC = 12 V 1.220
(1)
1.235 1.235 90
1.25 1.272
V V %
1.198
DC characteristics Iqop Iq Total operating quiescent current Quiescent current Duty Cycle = 0; VFB = 1.5 V Vinh > 2.2 V VCC = 36 V; Vinh > 2.2 V
(1) (1) (1)
3
5 2.5
mA mA A A
50 80
100 150
Iqst-by
Total stand-by quiescent current
Inhibit INH threshold voltage Error amplfier VOH VOL Io source Io sink High level output voltage Low level output voltage Source output current Sink output current VFB = 1 V VFB = 1.5 V VCOMP = 1.9 V; VFB = 1 V VCOMP = 1.9 V; VFB = 1.5 V 200 1 300 1.5 3.5 0.4 V V A mA Device ON Device OFF 2.2 0.8 V V
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Electrical characteristics Table 4.
Symbol Ib
L5973D
Electrical characteristics (continued) ( TJ = 25 C, VCC = 12 V, unless otherwise specified)
Parameter Source bias current DC open loop gain RL = Icomp = -0.1 mA to 0.1 mA VCOMP = 1.9 V 50 Test condition Min Typ 2.5 57 2.3 Max 4 Unit A dB mS
gm
Transconductance
Sync function High input voltage Low input voltage Slave sink current Master output amplitude Output pulse width Reference section Reference voltage IREF = 0 to 5 mA VCC = 4.4 V to 36 V Line regulation Load regulation Shor t circuit current IREF = 0 mA VCC = 4.4 V to 36 V IREF = 0 to 5 mA 10
(1)
VCC = 4.4 V to 36 V VCC = 4.4 V to 36 V Vsync = 0.74 V Vsync = 2.33 V Isource = 3 mA no load, Vsync = 1.65 V
(2)
2.5
VREF 0.74
V V mA mA V s
0.11 0.21 2.75 0.20 3 0.35
0.25 0.45
3.234 3.2
3.3 3.3 5 8 18
3.366 3.399 10 15 30
V V mV mV mA
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.
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L5973D
Typical characteristics
4
Typical characteristics
Figure 3.
Vo (V) 3.312 3.308 3.304 3.3 3.296 3.292 3.288 3.284 3.28 3.276 0 10 20 Vcc (V) 30 40 Vcc = 12V Vo = 3.3V Tj = 25C
Line regulation
Figure 4.
Ishd (A) 70
Shutdown current vs junction temperature
60
Vcc = 12V
50
Tj = 125C
40
30 -50 0 50 Tj (C) 100 150
Figure 5.
Vo (V) 1.25 1.24
Output voltage vs junction temperature
Figure 6.
Switching frequency vs junction temperature
Fsw (KHz) 260
250
1.23
240
1.22 Vcc = 12V 1.21 1.2 -50 0 50 Tj (C) 100 150 Vcc=12V
220 -50 0 50 Tj (C) 100 150 230 Vcc = 12V Vo = 3.3V
Figure 7.
Iq (mA)
Quiescent current vs junction temperature
2
1.8
1.6 Vcc = 12V DC = 0%
1.4
1.2 -50 0 50 Tj (C) 100 150
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Typical characteristics
L5973D
Figure 8.
Junction temperature vs output current
Figure 9.
Junction temperature vs output current
Tj(C) 120 110 Vin=5V 100 Tamb=25C 90 80 70 60 50 40 30 20 0.2 0.4 0.6 0.8 1
Tj (C) 120
Vo=3.3V Vo=2.5V
110 100 90 80 70 60 50 40 30 20
Vin=12V Tamb=25C
Vo=5V
Vo=3.3V
Vo=1.8V
Vo=2.5V
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 Io(A)
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8 Io (A)
2
2.2 2.4 2.6
Figure 10. Efficiency vs output current
Figure 11. Efficiency vs output current
95 93 91 89 87 85 83 81 79 77 75 73 71 69 67
Vo=3.3V
Vo=2.5V Vo=1.8V
Vin=5V
91 89 87 85 83 81 79 77 75 73 71 69 67 65
V o=5V Vo=3.3V Vo=2.5V
Efficiency (%)
Efficiency (%)
V i n = 1 2V
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 Io (A)
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 Io (A)
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L5973D
Application circuit
5
Application circuit
In figure 6 is shown the demonstration board application circuit, where the input supply voltage, VCC, can range from 4 V to 25 V due to the rated voltage of the input capacitor and the output voltage is adjustable from 1.235 V to VCC. Figure 12. Demonstration board application circuit
3.3V VIN = 4.4V to 25V
VREF VCC SYNC.
6 8 2 4 INH
1
OUT
L1 15H D1 STPS2L25U
VOUT=3.3V
L5973D
3 7 5 FB GND
R1 5.6K
C1 10F 25V CERAMIC
COMP C4 22nF C3 220pF R3 4.7K
C2 330F 6.3V
R2 3.3K
D03IN1440
Table 5.
Component list
Part number GRM32DR61E106KA12L POSCAP 6TPB330M C1206C221J5GAC C1206C223K5RAC Description 10 F, 25 V 330 F, 6.3 V 220 pF, 5%, 50 V 22 nF, 10%, 50 V 5.6 K, 1%, 0.1 W 0603 3.3 K, 1%, 0.1 W 0603 4.7 K, 1%, 0.1 W 0603 STPS2L25U DO3316P-153 2 A, 25 V 15 H, 3 A Manufacturer Murata Sanyo KEMET KEMET Neohm Neohm Neohm ST COILCRAFT
Reference C1 C2 C3 C4 R1 R2 R3 D1 L1
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Application circuit Figure 13. PCB layout (component side)
L5973D
Figure 14. PCB layout (bottom side)
Figure 15. PCB layout (front side)
Below some graphs show the TJ versus output current in different conditions of the input and output voltage and some efficiency measurements.
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L5973D
Application ideas
6
Application ideas
Figure 16. Positive buck-boost regulator
Figure 17. Buck-boost regulator
Figure 18. Dual output voltage with auxiliary winding
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Application ideas
L5973D
When an output voltage below the internal reference (1.235 V) is required, the circuit reported in the figure 18 can been used. In this case the minimum voltage reachable is 0.6 V and can be easily calculated with the following formula: VOUT = VFB - [(VREF - VFB)x(R2 / R1)] If the load is not present, a resistor connected between VOUT and GND is required in order to avoid that the voltage across COUT increases. The value of this resistor has to be calculated taking into account that the current flowing through this resistance has to be higher than the current flowing through R2. Figure 19. Output voltage below the 1.235 V internal voltage reference
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L5973D
Package mechanical data
7
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
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Package mechanical data Table 6.
Dim Min A A1 A2 b c D D1 E E1 E2 e h L k ccc 0.25 0.40 0.00 1.25 0.31 0.17 4.80 3 5.80 3.80 2.31 4.90 3.1 6.00 3.90 2.41 1.27 0.50 1.27 0.0098 0.0157 0.51 0.25 5.00 3.2 6.20 4.00 2.51 Typ Max 1.70 0.10 0.0492 0.0122 0.0067 0.1890 0.118 0.2283 0.1496 0.091 0.095 0.1929 0.122 0.00 Mi n Typ
L5973D
HSOP8 mechanical data
mm inch Max 0.0669 0.0039
0.0201 0.0098 0.1969 0.126 0.2441 0.1575 0.099
0.0197 0.0500
0 (min), 8 (max) 0.10 0.0039
Figure 20. Package dimensions
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L5973D
Order code
8
Order code
Table 7. Order code
Part number L5973D L5973D013TR Package HSOP8 (Exposed pad) HSOP8 (Exposed pad) Packaging Tube Tape and reel
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Revision history
L5973D
9
Revision history
Table 8.
Date 01-Nov-2005 22-May-2006 13-Nov-2006 26-Jan-2007 17-Oct-2007 24-Oct-2007 07-Jan-2008
pp
Revision history
Revision 10 11 12 13 14 15 16 Changes Updated package information Electrical characteristic Table 4 updated, new application idea Figure 19 added, new template Typo in order codes Updated Table 4 on page 5 Updated Section 5: Application circuit on page 9 Updated Table 6 on page 14 Updated Table 6 on page 14
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L5973D
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