FEATURES 1.5A STEP DOWN CONVERTER OPERATING INPUT VOLTAGE FROM PR
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L4971.5A STEP DOWN SWITCHING REGULATOR
FEATURES
1.5A STEP DOWN CONVERTER OPERATING INPUT VOLTAGE FROM PRECISE 3.3V (±1%) INTERNAL REFERENCE VOLTAGE OUTPUT VOLTAGE ADJUSTABLE FROM 3.3V SWITCHING FREQUENCY ADJUSTABLE 300KHz VOLTAGE FEEDFORWARD ZERO LOAD CURRENT OPERATION INTERNAL CURRENT LIMITING (PULSEBYPULSE HICCUP MODE) INHIBIT ZERO CURRENT CONSUMPTION PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN SOFT START FUNCTION
Figure Package
DIP8
SO16W
Table Order Codes
Part Number L4971 L4971D L4971D013TR Package DIP8 SO16W SO16 Tape Reel
switching frequency 300KHz achievable (the maximum power dissipation packages must observed). wide input voltage range between output voltages regulated from 3.3V cover majority today's applications. Features this generations DC-DC converter include pulse-by-pulse current limit, hiccup mode short circuit protection, voltage feedforward regulation, soft-start, protection against feedback loop disconnection, inhibit zero current consumption thermal shutdown. device available plastic dual line, DIP8 standard assembly, SO16W assembly.
DESCRIPTION
L4971 step down monolithic power switching regulator delivering 1.5A voltage between 3.3V (selected simple external divider). Realized mixed technology, device uses internal power D-MOS transistor (with typical Rdson 0.25) obtain very high efficency high switching speed. Figure Block Diagram
Vi=8V 220µF 220nF 2.7nF
L4974 126µH (77120) STPS 3L60U 330µF VO=3.3V/1.5A
100nF
9.1K 22nF
100nF
D97IN748A
2005
Rev. 1/13
L497Figure Block Diagram
THERMAL SHUTDOWN VOLTAGES MONITOR CBOOT CHARGE SS_INH INHIBIT SOFTSTART 3.3V COMP INTERNAL REFERENCE INTERNAL SUPPLY 5.1V BOOT
3.3V
DRIVE
OSCILLATOR
CBOOT CHARGE LIGHT LOADS
D97IN594
Figure Connections
N.C.
D97IN596
N.C. N.C. COMP BOOT N.C. N.C.
SS_INH
D97IN595
COMP BOOT
SS_INH N.C. N.C.
DIP8
SO16
Table Description
Name SS_INH Ground logic signal (active low) disables device (sleep mode operation). capacitor connected between this ground determines soft start time. When this grounded disabled device (driven open collector/drain). external resistor connected between unregulated input voltage this capacitor connected from this ground switching frequency. (Line feed forward automatically obtained) Stepdown regulator output Unregulated input voltage capacitor connected between this allows drive internal DMOS Transistor output used frequency compensation Stepdown feedback input. Connecting directly this results output voltage 3.3V. external resistive divider required higher output voltages. Function
BOOT COMP
Pins internally, electrically connected die.
2/13
L497Table Absolute Maximum Ratings
Symbol Minidip V6-V5 Ptot Tj,Tstg S016 V5,V6 I5,I6 V12-V11 Bootstrap voltage Analogs input voltage (VCC Analogs input voltage (VCC 24V) (VCC 20V) Power dissipation Tamb 60°C Junction storage temperature DIP8 SO16 Input voltage Output voltage Output peak voltage 0.1µs f=200KHz Maximum output current Parameter Value int. limit. -0.3 Unit
Table Thermal Data
Symbol Rth(j-amb) Parameter Thermal Resistance Junction ambient Max. DIP8 SO16 Unit °C/W
Package mounted board.
ELECTRICAL CHARACTERISTCS
Table 25°C, Cosc 2.7nF, Rosc 20k, 24V, unless otherwise specified.) Specification Refered from 125°C
Symbol Parameter Test Condition Min. Typ. Max. Unit
DYNAMIC CHARACTERISTIC Operating input voltage range Output voltage 50V; 1.5A 0.5A 1.5A Dropout voltage 10V; 1.5A Maximum limiting current Efficiency Switching frequency Supply voltage ripple rejection Voltage stability switching frequency Temp. stability switching frequency Vcc+2VRMS; Vref; 1.5A; ripple 100Hz 125°C 3.3V; 1.5A 3.33 3.292 3.22 3.36 3.36 3.36 0.44 3.39 3.427 0.55 0.88
SVRR
3/13
L497Table 25°C, Cosc 2.7nF, Rosc 20k, 24V, unless otherwise specified.) Specification Refered from 125°C
Soft Start Soft start charge current Soft start discharge current Inhibit IsLL level voltage Isource level
Characteristics
Iqop Iqst-by
Total operating quiescent current Quiescent current Total stand-by quiescent current Duty Cycle 3.8V Vinh <0.9V 55V; Vinh<0.9V
Error Amplifier Voltage Feedback Input Line regulation Ref. voltage stability temperature High level output voltage level output voltage Source output current Sink output current Source bias current Supply voltage ripple rejection open loop gain Transconductance Vcomp Vfb; Icomp -0.1 0.1mA Vcomp 2.5V 3.8V Vcomp 2.5V Vcomp VFB= 3.8V 10.3 0.65 3.33 3.36 3.39 mV/°C
source sink
SVRR
Oscillator Section Ramp Valley Ramp peak Maximum duty cycle Maximum Frequency Duty Cycle Rosc 13k, Cosc 820pF 0.78 0.85 2.15 0.92 10.2
4/13
L497Table Typical Performance (Using Evaluation Board) 100kHz
Output Voltage 3.3V 5.1V Output Ripple 10mV 10mV 12mV
Efficiency
=35V 1.5A
Line Regulation
1.5A (VCC 55V)
Load Regulation =35V 1.5A
Figure Test valuation board circuit.
Vi=8V 220µF 220nF 2.7nF
L4974 126µH (77120) PS3L60U 330µF
VO=3.3V/1.5A
100nF
9.1K 22nF
100nF
D97IN749A
C1=220µF/63V C2=2.7nF C5=100nF C6=100nF C7=220nF/63V C8=330µF/35V Sanyo L1=126µH KoolMu 77120 Turns 0.5mm R1=20K R2=9.1K D1=STPS3L60U
L497VO(V) R3(K) R4(K)
Figure component layout figure
5/13
L497Figure Quiescent drain current input voltage.
(mA)
200KHz R1=22K C2=1.2nF 100KHz R1=20K C2=2.7nF
D97IN724
Figure Line Regulation
3.377
Tj=125°C
D97IN733
3.376 3.375
Tj=25°C
3.374 3.373 3.372
Tamb=25°C
3.371 3.370
Vcc(V)
VCC(V)
Figure Quiescent current junction temperature
(mA)
D97IN73
Figure Line Regulation
3.378 3.376 3.374
Tj=25°C
D97IN734
VCC=35V
200KHz R1=22K C2=1.2nF 100KHz R1=20K C2=2.7nF
3.372 3.370 3.368 3.366 3.364 3.362
Tj=125°C
VCC=35V
Tj(°C)
3.360 IO(A)
Figure Stand-by drain current input voltage
Ibias (µA) VCC(V)
Tj=125°C Vss=GND Tj=25°C
D97IN732
Figure Switching frquency
(KHz)
D97IN784
Tamb=25°C
3.3n
4.7n
5.6n
R1(K)
6/13
L497Figure Switching Frequency input voltage.
(KHz) 107.5 105.0 102.5 100.0 97.5 95.0 92.5 90.0 VCC(V)
Tj=25°C
D97IN735
Figure Efficiency output voltage.
VO(V)
VCC=35V IO=1.5A 100KHz 200KHz
D97IN737
Figure Switching frequency junction temperature.
(KHz)
D97IN785
Figure Efficiency output current.
VCC=12V
D97IN738
VCC=8V
VCC=24V
Tj(°C)
VCC=48V fsw=100KHz VO=5.1V
IO(A)
Figure Dropout voltage between
Tj=125°C
D97IN736
Figure Efficiency output current.
VCC=12V VCC=24V VCC=8V
D97IN739
0.Tj=-25°C
VCC=48V
fsw=100KHz VO=3.36V
IO(A)
IO(A)
7/13
L497Figure Efficiency output current.
VCC=48V VCC=12V VCC=24V
D97IN740
Figure Power dissipation Vcc.
Pdiss (mW)
VO=5.1V fsw=100KHz
D97IN743
VCC=8V
IO=1.5A IO=1A
fsw=200KHz VO=5.1V
IO=0.5A
IO(A)
VCC(V)
Figure Efficiency output current.
IO(A)
VCC=8V
D97IN74
Figure Efficiency
Pdiss (mW)
VCC=35V fsw=100KHz
D97IN744
VCC=12V VCC=24V
IO=1.5A
IO=1A
VCC=48V fsw=200KHz VO=3.36V
IO=0.5A
V0(V)
Figure Efficiency VCC.
.1V-f
Figure Pulse pulse limiting current junction temperature.
D97IN742
Ilim
00KH
D97IN747
fsw=100KHz VCC=35V
3.36
IO=1.5A
VCC(V)
Tj(°C)
8/13
L497Figure Load transient. Figure Soft start capacitor selection Inductor Vccmax
(µH)
D97IN746
fsw=200KHz
56nF
47nF
33nF
22nF
VCCmax(V)
Figure Line transient.
100KHz
Figure Open loop frequency phase error amplifier
D97IN786
GAIN (dB)
GAIN
D97IN787
Phase
Phase
(mV)
-100
-100
1ms/DIV
-150 -200
f(Hz)
Figure Soft start capacitor selection inductor Vccmax.
(µH)
fsw=100KHz
D97IN745
680nF 470nF
330nF
220nF
100nF
VCCmax(V)
9/13
L497Figure DIP8 Mechanical Data Package Dimensions
DIM. MIN. 3.18 7.95 2.54 7.62 7.62 5.08 3.81 1.52 0.125 0.51 1.15 0.356 0.204 1.65 0.55 0.304 10.92 9.75 0.313 0.100 0.300 0.300 0.260 0.200 0.150 0.060 TYP. 3.32 0.020 0.045 0.014 0.008 0.065 0.022 0.012 0.430 0.384 MAX. MIN. TYP. 0.131 MAX. inch
OUTLINE MECHANICAL DATA
DIP-8
10/13
L497Figure SO16 Mechanical Data Package Dimensions
DIM. MIN. 10.0 0.25 0.40 2.35 0.10 0.33 0.23 10.10 7.40 1.27 10.65 0.75 1.27 0.394 0.010 0.016 TYP. MAX. 2.65 0.30 0.51 0.32 10.50 7.60 MIN. 0.093 0.004 0.013 0.009 0.398 0.291 0.050 0.419 0.030 0.050 TYP. MAX. 0.104 0.012 0.200 0.013 0.413 0.299 inch
OUTLINE MECHANICAL DATA
(min.), (max.) 0.10 0.004
dimension does include mold flash, protusions gate burrs. Mold flash, protusions gate burrs shall exceed 0.15mm side.
SO16 (Wide)
0016021
11/13
L497
REVISION HISTORY
Table Revision History
Date October 2004 2005 Revision First Issue EDOCS Updated Layout look feel. Changed name figs. Description Changes
12/13
L497
Information furnished believed accurate reliable. However, STMicroelectronics assumes responsibility consequences such information infringement patents other rights third parties which result from use. license granted implication otherwise under patent patent rights STMicroelectronics. Specifications mentioned this publication subject change without notice. This publication supersedes replaces information previously supplied. STMicroelectronics products authorized critical components life support devices systems without express written approval STMicroelectronics. logo registered trademark STMicroelectronics. other names property their respective owners 2005 STMicroelectronics rights reserved STMicroelectronics group 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 America www.st.com
13/13
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