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Part: EL7551CU-T13
Category:
Description: Pwm, DC-DC, Step-down (Buck), 1 Amp, With Power Transistors, Vin=4.5/5.5V, Vout=1.0/3.8V
Company: Intersil Corporation
Datasheet: Download EL7551CU-T13 datasheet File size : 485 kB
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Datasheet text preview:
®
EL7551
D a ta Sheet J anu a r y 24, 2002 FN7291
Monolithic 1Amp DC:DC Step-down Regulator
The EL7551 is an integrated, synchronous step-down regulator with output voltage adjustable from 1.0V to 3.8V. It is capable of delivering 1A continuous current at up to 95% efficiency. The EL7551 operates at a constant frequency pulse width modulation (PWM) mode, making external synchronization possible. Patented on-chip resistorless current sensing enables current mode control, which provides cycle-by-cycle current limiting, over-current protection, and excellent step load response. The EL7551 is available in a fused-lead 16-pin QSOP package. With proper external components, the whole converter fits into a less than 0.4 in2 area. The minimal external components and small size make this EL7551 ideal for desktop and portable applications. The EL7551 is specified for operation over the -40°C to +85°C temperature range.
Features
· Integrated synchronous MOSFETs and current mode controller · 1A continuous output current · Up to 95% efficiency · 4.5V to 5.5V input voltage · Adjustable output from 1V to 3.8V · Cycle-by-cycle current limit · Precision reference · ±0.5% load and line regulation · Adjustable switching frequency to 1.2MHz · Oscillator synchronization possible · Internal soft start · Over temperature protection · Under voltage lockout · 16-pin QSOP package
Pinout
EL7551 (16-PIN QSOP) TOP VIEW
Applications
· DSP, CPU Core and IO Supplies · Logic/Bus Supplies
C3
C4
1 SGND 2 COSC 3 VDD 4 PGND
PGND 16 C5 VREF 1 5 0.1µF FB 14 VDRV 13 LX 12 LX 11 VHI 1 0 PGND 9 C6 0.1µF 1k L1 R2 R1 2.37k
· Por table Equipment · DC:DC Converter Modules · GTL + Bus Power Supply
0.1µF 270pF R3 39
C1 10µF ceramic VIN (4.5V-5.5V)
5 PGND 6 VIN 7 VIN 8 EN
10µH
C7 VO 47µF (3.3V,1A)
Ordering Information
PART NUMBER EL755 1CU EL755 1CU-T 7 EL755 1CU-T 13 P ACKA GE 16-Pin QSOP 16-Pin QSOP 16-Pin QSOP TAPE & REEL 7" 13" PKG. NO. M DP0040 MDP0040 MDP0040
Manufactured under U.S. Patent No. 57,323,974
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2003. All Rights Reserved. Elantec is a registered trademark of Elantec Semiconductor, Inc. All other trademarks mentioned are the property of their respective owners.
EL7551
Absolute Maximum Ratings (TA = 25°C)
Supply Voltage between VIN or VDD and GND . . . . . . . . . . . . +6.5V VLX Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VIN +0.3V Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . GND -0.3V, VDD +0.3V VHI Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . GND -0.3V, VLX +6V Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C Operating Ambient Temperature . . . . . . . . . . . . . . . .-40°C to +85°C Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . +135°
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA
DC Electrical Specifications
PARAMETER VREF VREFTC VREFLOAD VRAMP IOSC_CHG IOSC_DIS IVDD+VDRV IVDD_OFF VDD_OFF VDD_ON TOT THYS ILEAK ILMAX RDSON RDSONTC VFB VFB_LINE VFB_LOAD VFB_TC IFB VEN_HI VEN_LO IEN Reference Accuracy
VDD = VIN = 5V, TA = TJ = 25°C, COSC = 1.2nF, unless otherwise specified. CONDITIONS M IN 1. 24 TYP 1.26 50 0 < IREF < 50µA -1 1.15 0.1V < VOSC < 1.25V 0.1V < VOSC < 1.25V VEN = 4V, FOSC = 120kHz EN = 0 3 .5 3. 95 135 20 EN = 0, LX = 5V (low FET), LX = 0V (high FET) 2 Wafer level test only 45 0.2 ILOAD = 0A VIN = 5V, VIN = 10%, ILOAD = 0A 0.1A < ILOAD < 1A -40°C < TA < 85°C, ILOAD = 0.5A VFB = 0V 0 . 9 60 0. 9 7 5 0.5 0.5 ±1 100 3.2 1 VEN = 0 -4 -2.5 200 4 0.99 95 10 200 8 3.5 1 5 1.5 4 4 .45 MA X 1.28 UNIT V ppm/° C % V µA mA mA mA V V °C °C µA A m m/°C V % % % nA V V µA
DESCRIPTION
Reference Temperature Coefficient Reference Load Regulation Oscillator Ramp Amplitude Oscillator Charge Current Oscillator Discharge Current VDD+VDRV Supply Current VDD Standby Current VDD for Shutdown VDD for Startup Over Temperature Threshold Over Temperature Hysteresis Internal FET Leakage Current Peak Current Limit FET On Resistance RDSON Tempco Output Initial Accuracy Output Line Regulation Output Load Regulation Output Temperature Stability Feedback Input Pull Up Current EN Input High Level EN Input Low Level Enable Pull Up Current
2
EL7551
Closed-Loop AC Electrical Specifications
PA RAMETER FOSC tSYNC MSS tBRM tLEB DMAX DESCRIPTION Oscillator Initial Accuracy Minimum Oscillator Sync Width Soft Start Slope FET Break Before Make Delay High Side FET Minimum On Time Maximum Duty Cycle VS = VIN = 5V, TA = TJ = 25°C, COSC = 1.2nF, unless otherwise specified. CONDITIONS M IN 105 TYP 117 25 0.5 15 150 95 M AX 130 UNIT kHz ns V /ms ns ns %
Pin Descriptions
PIN NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PIN NAME S GND C OSC V DD P GND P GND V IN V IN EN P GND VHI LX LX VDRV FB VREF PGND Control circuit negative supply. Oscillator timing capacitor. FOSC can be approximated by: FOSC (kHz) = 0.1843/COSC, COSC in µF. Control circuit positive supply. Ground return of the regulator. Connected to the source of the low-side synchronous NMOS power FET. Ground return of the regulator. Connected to the source of the low-side synchronous NMOS power FET. Power supply input of the regulator. Connected to the drain of the high-side NMOS power FET. Power supply input of the regulator. Connected to the drain of the high-side NMOS power FET. Chip Enable, active high. A 2µA internal pull-up current enables the device if the pin is left open. Ground return of the regulator. Positive supply of the high-side driver. Inductor drive pin. High current digital output whose average voltage equals the regulator output voltage. Inductor drive pin. High current digital output whose average voltage equals the regulator output voltage. Positive supply of the low-side driver and input voltage for the high-side boot strap. Voltage feedback input. Connected to an external resistor divider between VOUT and GND. A 125nA pull-up current forces VOUT to VS in the event that FB is floating. Bandgap reference bypass capacitor. Typically 0.1µF to GND. Ground return of the regulator. PIN FUNCTION
3
EL7551 Typical Performance Curves
Efficiency vs IO VIN=5V 100 VO=2.5V 95 0.2 90 85 VO=1.2V 80 75 70 0.05 65 60 0.1 FS=500kHz L=Coilcraft DO3316P-472 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0 .8 1 Load Current IO (A) Efficiency vs IO VO=3.3V 100 VIN=4.5V 95 Output Voltage (%) 90 Efficiency (%) VIN=5V 85 80 75 70 65 60 0 0.2 0 .4 0.6 0.8 1 Load Current IO (A) Line Regulation VO=3.3V 0.6 0.5 0.4 0.3 VO (%) 0.2 0.1 0 -0.1 1.246 -0.2 -0.3 -0.4 4.5 4.7 4.9 VIN (V) 5.1 5.3 5.5 1.244 1.242 -40 IO=1A IO=0.1A VREF (V) 1.254 1.252 1.25 1.248 1.258 1.256 FS=500kHz L=Coilcraft DO3316P-472 -0.6 0 0.2 0.4 0.6 0 .8 1 Load Current IO (A) VREF vs Temperature VIN=5.5V 0.4 0.2 VIN=5V 0 -0.2 -0.4 VIN=4.5V VIN=5.5V 0.6 Output Current IO (A) Load Regulation VO=3.3V VO=1V VO=3.3V VO=1V Power Loss (W) Efficiency (%) 0.15 VO=3.3V 0.1 VO=1.8V VO=1.5V 0.25 Power Loss vs IO VIN=5V
10
60 Temperature (°C)
110
160
4
EL7551 Typical Performance Curves
390 385 380 375 370 365 360 -40 Input Current (mA)
(Continued)
Input Current vs Temperature (Enable connected to GND) 0.96 0.94 0.92 0.9 0.88 0.86 0.84 0.82 0.8 -40 VIN=5V VIN=4.5V VIN=5.5V
Oscillator Frequency vs Temperature
Oscillator Frequency (kHz)
0
40 Temperature (°C)
80
120
10
60 Temperature (°C)
110
160
Switching Frequency vs COSC 1400 1200 1000 FS (kHz) 800 600 400 200 0 0 200 400 600 800 1000 COSC (pF) Transient Response VIN=5V, VO=3.8V, IO=0A-1A VO iL VI V LX
Switching Waveforms VIN=5V, VO=3.8V, IO=1A
Power-Up VIN=5V, VO=3.8V, IO=1A
iO
VIN
VO
VO
5
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