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EL7516
Data Sheet October 27, 2004 FN7333.3
600kHz/1.2MHz PWM Step-Up Regulator
The EL7516 is a high frequency, high efficiency step-up voltage regulator operated at constant frequency PWM mode. With an internal 1.5A, 200m MOSFET, it can deliver up to 600mA output current at over 90% efficiency. The selectable 600kHz and 1.2MHz allows smaller inductors and faster transient response. An external compensation pin gives the user greater flexibility in setting frequency compensation allowing the use of low ESR Ceramic output capacitors. When shut down, it draws < 10A of current and can operate down to 2.5V input supply. These features along with 1.2MHz switching frequency makes it an ideal device for portable equipment and TFT-LCD displays. The EL7516 is available in an 8-pin MSOP package with a maximum height of 1.1mm. The device is specified for operation over the full -40C to +85C temperature range.
Features
* > 90% efficiency * 1.6A, 200m power MOSFET * VIN > 2.5V * 600kHz/1.2MHz switching frequency selection * Adjustable soft-start * Internal thermal protection * 1.1mm max height 8-pin MSOP package * Pb-free available (RoHS compliant)
Applications
* TFT-LCD displays * DSL modems * PCMCIA cards * Digital cameras
Pinout
EL7516 (8-PIN MSOP) TOP VIEW
COMP 1 FB 2 SHDN 3 GND 4 8 SS 7 FSEL 6 VDD 5 LX
* GSM/CDMA phones * Portable equipment * Handheld devices
Ordering Information
PART NUMBER EL7516IY EL7516IY-T7 EL7516IY-T13 EL7516IYZ (See Note) EL7516IYZ-T7 (See Note) EL7516IYZ-T13 (See Note) PACKAGE 8-Pin MSOP 8-Pin MSOP 8-Pin MSOP 8-Pin MSOP (Pb-Free) 8-Pin MSOP (Pb-Free) 8-Pin MSOP (Pb-Free) TAPE & REEL 7" 13" 7" 13" PKG. DWG. # MDP0043 MDP0043 MDP0043 MDP0043 MDP0043 MDP0043
NOTE: Intersil Pb-free products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020C.
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 (c) Intersil Americas Inc. 2002-2004. All Rights Reserved. Elantec is a registered trademark of Elantec Semiconductor, Inc. All other trademarks mentioned are the property of their respective owners.
EL7516
Absolute Maximum Ratings (TA = 25C)
LX to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18V VDD to GND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V COMP, FB, SHDN, SS, FSEL to GND . . . . . . -0.3V to (VDD +0.3V) Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65C to +150C Operating Ambient Temperature . . . . . . . . . . . . . . . .-40C to +85C Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . +135C
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
Electrical Specifications PARAMETER IQ1 IQ2 IQ3 VFB IB-FB VDD DMAX-600kHz DMAX-1.2MHz ILIM ISHDN RDS-ON ILX-LEAK VOUT/VIN VOUT/IOUT FOSC1 FOSC2 VIL VIH GM AV VDD-ON VDD-OFF ISS RCS OTP
VIN = 3.3V, VOUT = 12V, IOUT = 0mA, FSEL = GND, TA = 25C unless otherwise specified. DESCRIPTION CONDITIONS SHDN = 0V SHDN = VDD, FB = 1.3V SHDN = VDD, FB = 1.0V 1.272 MIN TYP 0.6 0.7 1.3 1.294 0.01 2.6 FSEL = 0V FSEL = VDD 84 84 1.3 SHDN = 0V VDD = 2.7V, ILX = 1A VSW = 18V 3V < VIN < 5.5V, VOUT = 12V VIN = 3.3V, VOUT = 12V, IO = 30mA to 200mA FSEL = 0V FSEL = VDD 500 1000 90 90 1.5 0.01 0.2 0.01 0.1 6.7 620 1250 740 1500 0.5 2.7 I = 5A 90 130 350 2.40 2.20 4 2.51 2.30 6 0.08 130 2.60 2.40 8 170 3 0.1 2 1.309 0.5 5.5 MAX 10 UNIT A mA mA V A V % % A A A % mV/A kHz kHz V V 1/ V/V V V A V/A C
Quiescent Current - Shut-down Quiescent Current - Not Switching Quiescent Current - Switching Feedback Voltage Feedback Input Bias Current Start-Up Input Voltage Range Maximum Duty Cycle Maximum Duty Cycle Current Limit - Max Peak Input Current Shut-down Input Bias Current Switch ON Resistance Switch Leakage Current Line Regulation Load Regulation Switching Frequency Accuracy Switching Frequency Accuracy SHDN, FSEL Input Low Level SHDN, FSEL Input High Level Error Amp Tranconductance Voltage Gain VDD UVLO On Threshold VDD UVLO Off Threshold Soft-start Charge Current Current Sense Transresistance Over Temperature Protection
2
FN7333.3
EL7516 Block Diagram
FSEL SHDN SS
VDD
REFERENCE GENERATOR
OSCILLATOR
SHUTDOWN & START-UP CONTROL
LX PWM LOGIC CONTROLLER COMPARATOR FET DRIVER
CURRENT SENSE
GND
FB GM AMPLIFIER
COMP
Pin Descriptions
PIN NUMBER 1 2 3 4 5 6 7 8 PIN NAME COMP FB SHDN GND LX VDD FSEL SS DESCRIPTION Compensation pin. Output of the internal error amplifier. Capacitor and resistor from COMP pin to ground. Voltage feedback pin. Internal reference is 1.294V nominal. Connect a resistor divider from VOUT. VOUT = 1.294V (1 + R1 / R2). See Typical Application Circuit. Shutdown control pin. Pull SHDN low to turn off the device. Analog and power ground. Power switch pin. Connected to the drain of the internal power MOSFET. Analog power supply input pin. Frequency select pin. When FSEL is set low, switching frequency is set to 620kHz. When connected to high or VDD, switching frequency is set to 1.25MHz. Soft-start control pin. Connect a capacitor to control the converter start-up.
Typical Application Circuit
R3 3.9k C5 4.7nF 1 COMP R1 85.2k R2 10k 2 FB 3 SHDN 4 GND SS 8 FSEL 7 VDD 6 LX 5 C3 27nF C4 + C1 22F 10H + C2 22F 12V 2.7V TO 5.5V
0.1F
D1
3
FN7333.3
EL7516 Typical Performance Curves
95 LOAD REGULATION (%) 0 100 200 IOUT (mA) 300 400
0.6 0.4
EFFICIENCY (%)
90
0.2 0 -0.2 -0.4 -0.6 -0.8
85
80
75
-1
0
50
100
150
200
250
300
350
IOUT (mA)
FIGURE 1. EFFICIENCY - 3.3V VIN TO 12V VOUT @ 1.3MHz
FIGURE 2. LOAD REGULATION - 3.3V VIN TO 12V VOUT @ 1.3MHz
90 LOAD REGULATION (%) 0 100 200 IOUT (mA) 300 400
1
EFFICIENCY (%)
0.5
85
0
80
-0.5
75
-1
0
50
100
150
200
250
300
350
IOUT (mA)
FIGURE 3. EFFICIENCY - 3.3V VIN TO 12V VOUT @ 620kHz
FIGURE 4. LOAD REGULATION - 3.3V VIN TO 12V VOUT @ 620kHz
95 90 EFFICIENCY (%) 85 80 75 70 LOAD REGULATION (%) 0 100 200 300 400 500
1
0.5
0
-0.5
-1
0
100
200
300
400
500
IOUT (mA)
IOUT (mA)
FIGURE 5. EFFICIENCY - 3.3V VIN TO 9V VOUT @ 1.2MHz
FIGURE 6. LOAD REGULATION - 3.3V VIN TO 9V VOUT @ 1.2MHz
4
FN7333.3
EL7516 Typical Performance Curves
(Continued)
90 LOAD REGULATION (%) 0 100 200 300 400 500
1 0.6 0.2 -0.2 -0.6 -1
EFFICIENCY (%)
85
80
75
0
100
200
300
400
500
IOUT (mA)
IOUT (mA)
FIGURE 7. EFFICIENCY - 3.3V VIN TO 9V VOUT @ 600kHz
FIGURE 8. LOAD REGULATION - 3.3V VIN TO 9V VOUT @ 600kHz
95 LOAD REGULATION (%) 0 100 200 300 IOUT (mA) 400 500 600
0.8 0.6
EFFICIENCY (%)
90
0.4 0.2 1 -0.2 -0.4 -0.6 -0.8
85
80
75
-1
0
100
200
300 IOUT (mA)
400
500
600
FIGURE 9. EFFICIENCY - 5V VIN TO 12V VOUT @ 1.2MHz
FIGURE 10. LOAD REGULATION - 5V VIN TO 12V VOUT @ 1.2MHz
92 LOAD REGULATION (%) 100 200 400
0.8 0.6
EFFICIENCY (%)
90
0.4 0.2 1 -0.2 -0.4 -0.6 -0.8
88
86
84
0
300 IOUT (mA)
500
600
-1
0
100
200
300 IOUT (mA)
400
500
600
FIGURE 11. EFFICIENCY - 5V VIN TO 12V VOUT @ 600kHz
FIGURE 12. LOAD REGULATION - 5V VIN TO 12V VOUT @ 600kHz
5
FN7333.3
EL7516 Typical Performance Curves
(Continued)
95 LOAD REGULATION (%) 0 400 800 1K
0.6 0.4
EFFICIENCY (%)
90
0.2 0 -0.2 -0.4 -0.6 -0.8
85
80
75
200
600
-1
0
200
400
600
800
1K
IOUT (mA)
IOUT (mA)
FIGURE 13. EFFICIENCY - 5V VIN TO 9V VOUT @ 1.2MHz
FIGURE 14. LOAD REGULATION - 5V VIN TO 9V VOUT @ 1.2MHz
0.2
VOUT=12V IOUT=80mA LINE REGULATION (%) 1.2MHz
0.1
VOUT=8V IOUT=80mA 1.2MHz
LINE REGULATION (%)
0.1
0.05
0 600kHz -0.1
0 600kHz
-0.05
-0.2
2
3
4 VIN (V)
5
6
-0.1 2.5
3.5
4.5 VIN (V)
5.5
6.5
FIGURE 15. LINE REGULATION
FIGURE 16. LINE REGULATION
95 600kHz 90 EFFICIENCY (%) 85 1.2MHz 80 75 70 10 LOAD REGULATION (%)
0.5 1.2MHz 0.3 0.1 -0.1 -0.3 -0.5 600kHz
110
210
310 IOUT (mA)
410
510
610
0
100
200
300 IOUT (mA)
400
500
600
FIGURE 17. EFFICIENCY vs IOUT - 3.3V TO 8V
FIGURE 18. LOAD REGULATION - 3.3V TO 8V
6
FN7333.3
EL7516 Typical Performance Curves
(Continued)
94 92 FREQUENCY (MHz) 90 EFFICIENCY (%) 88 86 84 82 80 78 76 0 200 400 600 IOUT (mA) 600kHz 800 1K 1.2K 1.2MHz
1.29 1.28 1.27 1.26 1.25 1.24 1.23 1.22 1.21 1.2 2.5 3 3.5 4 VIN (V) 4.5 5 5.5
FIGURE 19. EFFICIENCY vs IOUT
FIGURE 20. FREQUENCY (1.2MHz) vs VIN
670 660 FREQUENCY (kHz) 650 640 630 620 610 600 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 EFFICIENCY (kHz)
93 91 89 87 85 83 81
0
200
400
600
800
1K
IOUT (mA)
FIGURE 21. FREQUENCY (600kHz) vs VIN
FIGURE 22. EFFICIENCY - 5V VIN TO 9V VOUT @ 600kHz
0.4 LOAD REGULATION (%) VIN = 3.3V VOUT = 12V IOUT = 50mA TO 300mA
0.2
0
200mV/DIV
-0.2
-0.4
0
200
400
600
800
1K
0.1ms/DIV
IOUT (mA)
FIGURE 23. LOAD REGULATION - 5V VIN TO 9V VOUT @ 600kHz
FIGURE 24. TRANSIENT REPONSE - 600kHz
7
FN7333.3
EL7516 Typical Performance Curves
(Continued)
1 POWER DISSIPATION (W) VIN = 3.3V VOUT = 12V IOUT = 50mA TO 300mA 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.1ms/DIV
JEDEC JESD51-7 HIGH EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD
870mW
JA =
200mV/DIV
M SO 11 P8 5 C/ W
0
25
50
75 85
100
125
AMBIENT TEMPERATURE (C)
FIGURE 25. TRANSIENT RESPONSE - 1.2MHz
FIGURE 26. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE
0.6 POWER DISSIPATION (W) 0.5
JEDEC JESD51-3 LOW EFFECTIVE THERMAL CONDUCTIVITY TEST BOARD
486mW 0.4 0.3 0.2 0.1 0
JA =
M SO P8 20 6 C/ W
0
25
50
75 85
100
125
AMBIENT TEMPERATURE (C)
FIGURE 27. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE
Applications Information
The EL7516 is a high frequency, high efficiency boost regulator operated at constant frequency PWM mode. The boost converter stores energy from an input voltage source and deliver it to a higher output voltage. The input voltage range is 2.5V to 5.5V and output voltage range is 5V to 18V. The switching frequency is selectable between 600KHz and 1.2MHz allowing smaller inductors and faster transient response. An external compensation pin gives the user greater flexibility in setting output transient response and tighter load regulation. The converter soft-start characteristic can also be controlled by external CSS capacitor. The SHDN pin allows the user to completely shut-down the device.
the boost converter operates in two cycles. During the first cycle, as shown in Figure 29, the internal power FET turns on and the Schottky diode is reverse biased and cuts off the current flow to the output. The output current is supplied from the output capacitor. The voltage across the inductor is VIN and the inductor current ramps up in a rate of VIN / L, L is the inductance. The inductance is magnetized and energy is stored in the inductor. The change in inductor current is:
V IN I L1 = T1 x --------L D T1 = ----------F SW D = Duty Cycle I OUT V O = --------------- x T 1 C OUT
Boost Converter Operations
Figure 28 shows a boost converter with all the key components. In steady state operating and continuous conduction mode where the inductor current is continuous, 8
FN7333.3
EL7516
During the second cycle, the power FET turns off and the Schottky diode is forward biased, Figure 30. The energy stored in the inductor is pumped to the output supplying output current and charging the output capacitor. The Schottky diode side of the inductor is clamp to a Schottky diode above the output voltage. So the voltage drop across the inductor is VIN - VOUT. The change in inductor current during the second cycle is:
V IN - V OUT I L = T2 x ------------------------------L 1-D T2 = -----------F SW
L VIN CIN EL7516 COUT D VOUT
IL2 T2
IL VO
For stable operation, the same amount of energy stored in the inductor must be taken out. The change in inductor current during the two cycles must be the same.
I1 + I2 = 0 V IN 1 - D V IN - V OUT D ----------- x --------- + ------------ x ------------------------------- = 0 L F SW L F SW V OUT 1 --------------- = -----------1-D V IN
FIGURE 30. BOOST CONVERTER - CYCLE 2, POWER SWITCH OPEN
Output Voltage
An external feedback resistor divider is required to divide the output voltage down to the nominal 1.294V reference voltage. The current drawn by the resistor network should be limited to maintain the overall converter efficiency. The maximum value of the resistor network is limited by the feedback input bias current and the potential for noise being coupled into the feedback pin. A resistor network less than 100K is recommended. The boost converter output voltage is determined by the relationship:
R 1 V OUT = V FB x 1 + ------ R 2
L VIN CIN EL7516
D VOUT COUT
The nominal VFB voltage is 1.294V.
Inductor Selection
The inductor selection determines the output ripple voltage, transient response, output current capability, and efficiency. Its selection depends on the input voltage, output voltage, switching frequency, and maximum output current. For most applications, the inductance should be in the range of 2H to 33H. The inductor maximum DC current specification must be greater than the peak inductor current required by the regulator. The peak inductor current can be calculated:
I OUT x V OUT V IN x ( V OUT - V IN ) I L ( PEAK ) = ----------------------------------- + 1 2 x ---------------------------------------------------V IN L x V OUT x FREQ
IL T1 IL1
FIGURE 28. BOOST CONVERTER
L VIN CIN EL7516 COUT VOUT
Output Capacitor
Low ESR capacitors should be used to minimized the output voltage ripple. Multilayer ceramic capacitors (X5R and X7R) are preferred for the output capacitors because of their lower ESR and small packages. Tantalum capacitors with higher ESR can also be used. The output ripple can be calculated as:
I OUT x D V O = -------------------------- + I OUT x ESR F SW x C O
VO
FIGURE 29. BOOST CONVERTER - CYCLE 1, POWER SWITCH CLOSED
9
FN7333.3
EL7516
For noise sensitive application, a 0.1F placed in parallel with the larger output capacitor is recommended to reduce the switching noise coupled from the LX switching node.
Shut-Down Control
When shut-down in is pulled low, the EL7516 is shut-down reducing the supply current to <3A.
Schottky Diode
In selecting the Schottky diode, the reverse break down voltage, forward current and forward voltage drop must be considered for optimum converter performance. The diode must be rated to handle 1.5A, the current limit of the EL7516. The breakdown voltage must exceed the maximum output voltage. Low forward voltage drop, low leakage current, and fast reverse recovery will help the converter to achieve the maximum efficiency.
Maximum Output Current
The MOSFET current limit is nominally 1.5A and guaranteed 1.3A. This restricts the maximum output current IOMAX based on the following formula:
I L = I L-AVG + ( 1 2 x I L )
where: IL = MOSFET current limit IL-AVG = average inductor current IL = inductor ripple current
V IN x [ ( V O + V DIODE ) - V IN ] I L = -----------------------------------------------------------------------------L x ( V O + V DIODE ) x F S
Input Capacitor
The value of the input capacitor depends the input and output voltages, the maximum output current, the inductor value and the noise allowed to put back on the input line. For most applications, a minimum 10F is required. For applications that run close to the maximum output current limit, input capacitor in the range of 22F to 47F is recommended. The EL7516 is powered from the VIN. To. High frequency 0.1F by-pass cap is recommended to be close to the VIN pin to reduce supply line noise and ensure stable operation.
VDIODE = Schottky diode forward voltage, typically, 0.6V FS = switching frequency, 600KHz or 1.2MHz
I OUT I L-AVG = ------------1-D
Loop Compensation
The EL7516 incorporates an transconductance amplifier in its feedback path to allow the user some adjustment on the transient response and better regulation. The EL7516 uses current mode control architecture which has a fast current sense loop and a slow voltage feedback loop. The fast current feedback loop does not require any compensation. The slow voltage loop must be compensated for stable operation. The compensation network is a series RC network from COMP pin to ground. The resistor sets the high frequency integrator gain for fast transient response and the capacitor sets the integrator zero to ensure loop stability. For most applications, the compensation resistor in the range of 2K to 7.5K and the compensation capacitor in the range of 3nF to 10nF.
D = MOSFET turn-on ratio:
V IN D = 1 - -------------------------------------------V OUT + V DIODE
The following table gives typical maximum Iout values for 1.2MHz switching frequency and 22H inductor:
TABLE 1. VIN (V) 2.5 2.5 2.5 3.3 3.3 3.3 5 5 VOUT (V) 5 9 12 5 9 12 9 12 IOMAX (mA) 570 325 250 750 435 330 650 490
Soft-Start
The soft-start is provided by an internal 6A current source charges the external CSS, the peak MOSFET current is limited by the voltage on the capacitor. This in turn controls the rising rate of the output voltage. The regulator goes through the start-up sequence as well after the SHDN pin is pulled to HI.
Frequency Selection
The EL7516 switching frequency can be user selected to operate at either at constant 620kHz or 1.25MHz. Connecting FSEL pin to ground sets the PWM switching frequency to 620kHz. When connect FSEL high or VDD, switching frequency is set to 1.25MHz.
Thermal Performance
The EL7516 uses a fused-lead package, which has a reduced JA of 100C/W on a four-layer board and 115C/W on a two-layer board. Maximizing copper around the ground pins will improve the thermal performance. This device also has internal thermal shut-down set at around 130C to protect the component.
FN7333.3
10
EL7516
Layout Considerations
To achieve highest efficiency, best regulation and most stable operation, a good printed circuit board layout is essential. It is strongly recommended that the demoboard layout to be followed as closely as possible. Use the following general guidelines when laying out the print circuit board: 1. Place C4 as close to the VDD pin as possible. C4 is the supply bypass capacitor of the device. 2. Keep the C1 ground, GND pin and C2 ground as close as possible. 3. Keep the two high current paths a) from C1 through L1, to the LX pin and GND and b) from C1 through L1, D1, and C2 as short as possible. 4. High current traces should be short and as wide as possible. 5. Place feedback resistor close to the FB pin to avoid noise pickup. 6. Place the compensation network close to the COMP pin. The demo board is a good example of layout based on these principles; it is available upon request.
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation's quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements 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 Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com 11
FN7333.3

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