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L5970D
UP TO 1A STEP DOWN SWITCHING REGULATOR
s s s s s s s s s s s s s
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 SINCHRONIZATION PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN
SO8 ORDERING NUMBERS: L5970D (SO8) L5970D013TR (T&R)
DESCRIPTION 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) 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.
APPLICATIONS: s CONSUMER: STB, DVD, TV, VCR,CAR RADIO, LCD MONITORS s NETWORKING: XDSL, MODEMS,DC-DC MODULES s COMPUTER: PRINTERS, AUDIO/GRAPHIC CARDS, OPTICAL STORAGE, HARD DISK DRIVE s INDUSTRIAL: CHARGERS, CAR BATTERY DC-DC CONVERTERS TEST APPLICATION CIRCUIT
3.3V VIN = 4.4V to 35V
VREF VCC SYNC.
6 8 2 4 INH.
1
OUT
L1 33H D1 STPS2L40U
VOUT=3.3V
L5970D
3 7 5 GND FB
R1 5.6K
C1 10F 35V CERAMIC
COMP C4 22nF C3 220pF
C2 100F 10V
R3 4.7K
R2 3.3K
D98IN954C
May 2003
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L5970D
PINS CONNECTION (Top View)
OUT SYNC INH COMP
1 2 3 4
D98IN955
8 7 6 5
VCC GND VREF FB
PINS FUNCTION
N. 1 2 3 4 5 6 7 8 Name 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 1.23V. An external resistive divider is required for higher output voltages. 3.3V VREF. No cap is requested for stability. Ground. Unregulated DC input voltage. Description
THERMAL DATA
Symbol
(*) Package mounted on board
Parameter
Value 120 (*)
Unit C/W
Rth (j-amb) Thermal Resistance Junction to ambient Max.
ABSOLUTE MAXIMUM RATINGS
Symbol V8 V1 I1 V4, V5 V3 V2 Ptot Tj Tstg Input Voltage Output DC voltage Output peak voltage at t = 0.1s Maximum output current Analog pins INH SYNC Power dissipation at Tamb 60C Operating junction temperature range Storage temperature range Parameter Value 40 -1 to 40 -5 to 40 int. limit. 4 -0.3V to VCC -0.3 to 4 0.75 -40 to 150 -55 to 150 V W C C V Unit V V V
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ELECTRICAL CHARACTERISTCS (Tj = 25C, VCC = 12V, unless otherwise specified.) (*) Specification Referred to Tj from -40 to +125C (1).
Symbol VCC Vd Il fs Parameter Operating input voltage range Dropout voltage Maximum limiting current Switching frequency Duty cycle DYNAMIC CHARACTERISTICS (see test circuit fig. xx note 1). V5 Voltage feedback 4.4V < VCC < 36V, 20mA < IO < 1A Efficiency VO = 5V, VCC = 12V * Duty Cycle = 0; VFB = 1.5V Vinh > 2.2V VCC = 36V; Vinh > 2.2V Device ON Device OFF VFB = 1V VFB = 1.5V VCOMP = 1.9V; VFB = 1V Vcomp = 1.9V; VFB = 1.5V RL = Icomp = -0.1mA to 0.1mA Vcomp = 1.9V VCC = 4.4V to 36V VCC = 4.4V to 36V Vsync = 0.74V Vsync = 2.33V Isource = 3mA no load, Vsync = 1.65V
(2)
Test Condition Vo = 1.235V; Io = 1A VCC = 4.4V; Io = 1A VCC = 4.4V to 36V
* * * *
Min. 4.4
Typ.
Max. 36 0.5 2.25 280 275 100 1.25 1.272
Unit V V A KHz KHz % V V %
0.25 1.5 212 225 0 1.220 1.198 1.87 250 250
*
1.235 1.235 90 3
DC CHARACTERISTICS Total operating quiescent Iqop current Quiescent current Iq Iqst-by INHIBIT INH Threshold voltage ERROR AMPLIFIER High level output voltage VOH VOL Io source Io sink Ib gm Low level output voltage Source output current Sink output current Source bias current DC open loop gain Transconductance Total stand-by quiescent current
5 2.5
mA mA A A V V V
* *
50 80
100 150 0.8
2.2 3.5 0.4 200 1 50 300 1.5 2.5 65 2.3 4
V A mA A dB mS
SYNC FUNCTION High Input Voltage Low Input Voltage Slave Sink Current Master Output Amplitude Output Pulse Width REFERENCE SECTION Reference Voltage
2.5 0.11 0.21 2.75 0.20 3.234 3.2 3 0.35 3.3 3.3 5 8 10 8
VREF 0.74 0.25 0.45
V V mA mA V s
IREF = 0 to 5mA VCC = 4.4V to 36V Line Regulation Load Regulation Short Circuit Current IREF = 0mA VCC = 4.4V to 36V IREF = 0 to 5mA
*
3.366 3.399 10 15 30
V V mV mV mA
Note (1): Specification over the -40 to +125 Tj Temperature range are assured by design, characterization and statistical correlation. Note (2): Guaranteed by design.
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L5970D
Figure 1. Junction Temperature vs. Output Current (SO8) *)
Tj(C)
Figure 4. Load Regulation
Vo (V) 3.312 3.308 Vcc = 12V Vo = 3.3V Tj = 25C 3.304 3.3 3.296 3.292 3.288 3.284 3.28 3.276 0 0.5 Io (A) 1 1.5 Tj = 125C
130 120 110 100 90 80 70 60 50 40 30 20 0.2
Vo=3.3V
Vo=2.5V
Vcc=5V Tamb=25C
Vo=1.8V
0.4
0.6
0.8
Io(A)
1
1.2
1.4
1.6
Figure 5. Line Regulation Figure 2. Junction Temperature vs. Output Current (SO8) *)
Tj(C)
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 Tj = 125C Vcc = 12V Vo = 3.3V Tj = 25C
130 120 110 100 90 80 70 60 50 40 30 20 0.2
Vo=5V
Vo=3.3V
Vcc=12V Tamb=25C
Vo=2.5V
0.4
0.6
0.8
Io(A)
1
1.2
1.4
1.6
Figure 3. Junction Temperature vs. Output Current (SO8) *)
Tj(C)
Figure 6. Output Voltage vs. Junction Temperature
Vo (V) 1.25 1.24 1.23
140
Vo=18V
Vo=12V
120 100 80 60 40 20 0 0.2 0.4 0.6 0.8
Io(A) Vcc=24V Tamb=25C Vo=5V
1.22 Vcc = 12V 1.21 1.2 -50
1 1.2 1.4
Vcc=12V
0
50 Tj (C)
100
150
*) Package mounted on demoboard
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Figure 7. Quiescent Current vs. Junction Temperature
Iq (mA)
Figure 9. Switching Frequency vs.Junction Temperature
Fsw (KHz) 260
2
1.8
250
1.6 Vcc = 12V DC = 0%
240
1.4
230
Vcc = 12V Vo = 3.3V
1.2 -50 0 50 Tj (C) 100 150
220 -50 0 50 Tj (C) 100 150
Figure 8. Shutdown Current vs.Junction Temperature
Ishd (A) 70
60
Vcc = 12V
50
40
30 -50 0 50 Tj (C) 100 150
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Figure 10. Demoboard schematic
VREF VCC SYNC. C1 10F 25V CERAMIC COMP C4 22nF C3 220pF
3.3V VIN = 4.4V to 25V
6 8 2 4 INH.
1
OUT
L1 33H D1 STPS2L25U
VOUT=3.3V
L5970D
3 7 5 GND FB
R1 5.6K
C2 100F 10V
R3 4.7K
R2 3.3K
D03IN1437
Part list demoboard
Reference C1 C2 C3 C4 R1 R2 R3 D1 L1 STPS2L25U DO3316P-333 POSCAP 10TPB100M C1206C221J5GAC C1206C223K5RAC Part Number Description 10F, 25V 100F, 10V 220pF, 5%, 50V 22nF, 10%, 50V 5.6K, 1%, 0.1W 0603 3.3K, 1%, 0.1W 0603 4.7K, 1%, 0.1W 0603 2A, 25V 33H, 2A Manufacturer TOKIN Sanyo KEMET KEMET Neohm Neohm Neohm STMicroelectronics COILCRAFT
Figure 11. Efficiency vs. Output Current
94 92 90 88 86 84 82 80 78 76 74 72 70 0.1
Figure 12. Efficiency vs. Output Current
92 90 88 86 84 82 80 78 76 74 72 70
Vo=5V Vo=3.3V
Vo=3.3V Vo=2.5V
Efficiency (%)
Vo=1.8V
Efficiency (%)
Vo=2.5V Vcc=12V
Vcc=5V 0.2 0.3 0.4 0.5 0.6 Io (A) 0.7 0.8 0.9 1
0.1
0.2
0.3
0.4
0.5 0.6 Io (A)
0.7
0.8
0.9
1
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Figure 13. PCB layout (component side)
42mm
34mm
Figure 14. PCB layout (bottom side)
Figure 15. PCB layout (front side)
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APPLICATION IDEAS Figure 16. Dual output voltage with auxiliary winding
N1/N2=2 D2 1N4148 VOUT1=5V 30mA
VIN=12V
VCC
OUT
Lp=22uH
D1 STPS25L25U
8
COMP C1 10uF 25V Ceramic
1 U1 L5970D
FB
VOUT=3.3V 0.5A C4 100uF 10V C5 47uF 10V
4 2 6
GND
7
5 3
INH
C2 220pF
C3 22nF R3 4.7k
SYNC VREF
3.3V
Figure 17. Buck-Boost regulator
VIN=12V VCC OUT
L1 33uH
8 U1
COMP C1 10uF 25V Ceramic C2 10uF 35V C3 Ceramic 220pF
1
D1 STPS2L25U 2.7k VOUT=-12V/0.3A
L5970 4 2 6
GND
7
5 3
FB
C4 22nF R3 4.7k
SYNC VREF
INH
24k
C5 100uF 16V
3.3V
Vin=12V Vout=-12V
Iout=0.5A Efficiency=81%
Figure 18. Positive Buck-Boost regul
VIN=5V
L1 33uH
VCC
8 U1 L5970 4 2 6
GND
OUT
D2 STPS2L25U
VOUT=12V/0.3A
1
D1 STPS2L25U 24k
COMP C1 10uF 25V Ceramic
7
5 3
FB
C2 220pF
C3 22nF R3 4.7k
M1 STN4NE03L
2.7k
SYNC VREF
INH
C4 100uF 16V
3.3V
Vin=5V Vout=12V Iout=0.3A Efficiency=76%
Figure 19. Synchronization example
VIN VCC OUT VCC OUT
8 L5970D 4 2
SYNC VREF
1
FB COMP
8 L5970D 4 2
SYNC VREF
1
FB
COMP
6
GND
7
5 3
6
GND
7
5 3
INH
INH
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L5970D
DIM. MIN. A a1 a2 a3 b b1 C c1 D (1) E e e3 F (1) L M S 3.8 0.4 4.8 5.8 0.65 0.35 0.19 0.25 0.1
mm TYP. MAX. 1.75 0.25 1.65 0.85 0.48 0.25 0.5 0.026 0.014 0.007 0.010 0.004 MIN.
inch TYP. MAX. 0.069 0.010 0.065 0.033 0.019 0.010 0.020
OUTLINE AND MECHANICAL DATA
45 (typ.) 5.0 6.2 1.27 3.81 4.0 1.27 0.6 8 (max.) 0.15 0.016 0.189 0.228 0.050 0.150 0.157 0.050 0.024 0.197 0.244
SO8
(1) D and F do not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch).
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L5970D
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. STMicroelectronics acknowledges the trademarks of all companies referred to in this document. The ST logo is a registered trademark of STMicroelectronics (c) 2003 STMicroelectronics - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan -Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - United States. http://www.st.com
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