EL7530IYZ [INTERSIL]

Monolithic 600mA Step-Down Regulator with Low Quiescent Current; 单片600mA降压稳压器具有低静态电流
EL7530IYZ
型号: EL7530IYZ
厂家: Intersil    Intersil
描述:

Monolithic 600mA Step-Down Regulator with Low Quiescent Current
单片600mA降压稳压器具有低静态电流

稳压器 开关 光电二极管
文件: 总11页 (文件大小:475K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
EL7530  
®
Data Sheet  
August 10, 2005  
FN7434.3  
Monolithic 600mA Step-Down Regulator  
with Low Quiescent Current  
Features  
2
• Less than 0.18in footprint for the complete 600mA  
converter  
The EL7530 is a synchronous, integrated FET 600mA step-  
down regulator with internal compensation. It operates with  
an input voltage range from 2.5V to 5.5V, which  
• Components on one side of PCB  
• Max height 1.1mm MSOP10  
accommodates supplies of 3.3V, 5V, or a Li-Ion battery  
source. The output can be externally set from 0.8V to V  
with a resistive divider.  
• Power-Good (PG) output  
IN  
• Internally-compensated voltage mode controller  
• Up to 95% efficiency  
The EL7530 features automatic PFM/PWM mode control, or  
PWM mode only. The PWM frequency is typically 1.4MHz  
and can be synchronized up to 12MHz. The typical no load  
quiescent current is only 120µA. Additional features include  
a Power-Good output, <1µA shut-down current, short-circuit  
protection, and over-temperature protection.  
• <1µA shut-down current  
• 120µA quiescent current  
• Overcurrent and over-temperature protection  
• External synchronizable up to 12MHz  
• Pb-Free plus anneal available (RoHS compliant)  
The EL7530 is available in the 10-pin MSOP package,  
2
making the the entire converter occupy less than 0.18n of  
PCB area with components on one side only. The 10-pin  
MSOP package is specified for operation over the full -40°C  
to +85°C temperature range.  
Applications  
• PDA and pocket PC computers  
• Bar code readers  
Ordering Information  
• Cellular phones  
PART NUMBER  
TAPE &  
REEL  
PKG.  
(BRAND)  
PACKAGE  
DWG. #  
• Portable test equipment  
• Li-Ion battery powered devices  
• Small form factor (SFP) modules  
EL7530IY  
(BYAAA)  
10-Pin MSOP  
-
MDP0043  
MDP0043  
MDP0043  
MDP0043  
MDP0043  
MDP0043  
EL7530IY-T7  
(BYAAA)  
10-Pin MSOP  
10-Pin MSOP  
7”  
Pinout and Typical Application Diagram  
EL7530IY-T13  
(BYAAA)  
13”  
-
EL7530  
TOP VIEW  
EL7530IYZ  
(BAADA) (Note)  
10-Pin MSOP  
(Pb-free)  
EL7530IYZ-T7  
(BAADA) (Note)  
10-Pin MSOP  
(Pb-free)  
7”  
R *  
1
100k  
SGND  
PGND  
LX  
FB  
VO  
PG  
EN  
1
2
3
4
5
10  
9
C
EL7530IYZ-T13  
(BAADA) (Note)  
10-Pin MSOP  
(Pb-free)  
13”  
R *  
2
124kΩ  
4
C
10µF  
C
2
10µF  
1
470pF  
PG  
NOTE: Intersil Pb-free plus anneal 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-020.  
L
1
8
1.8µH  
V
(1.8V@600mA)  
O
EN  
VIN  
7
R
100Ω  
3
V
(2.5V-6V)  
S
SYNC  
VDD  
SYNC 6  
R
C
3
0.1µF  
6
100kΩ  
R
R
100kΩ  
100kΩ  
4
5
* V = 0.8V * (1 + R / R )  
O
2
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.  
1
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.  
Copyright © Intersil Americas Inc. 2004-2005. All Rights Reserved.  
All other trademarks mentioned are the property of their respective owners.  
EL7530  
Absolute Maximum Ratings (T = 25°C)  
Thermal Information  
Thermal Resistance (Typical)  
MSOP10 Package (Note 1) . . . . . . . . . . . . . . . . . . .  
Operating Ambient Temperature . . . . . . . . . . . . . . . .-40°C to +85°C  
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C  
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +125°C  
A
V
, V , PG to SGND . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V  
θ
(°C/W)  
115  
IN DD  
JA  
LX to PGND . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (V + +0.3V)  
IN  
IN  
SYNC, EN, V , FB to SGND. . . . . . . . . . . . . -0.3V to (V + +0.3V)  
O
PGND to SGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +0.3V  
Peak Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800mA  
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. Typ values are for information purposes only. Unless otherwise noted, all tests are  
at the specified temperature and are pulsed tests, therefore: T = T = T  
A
J
C
NOTE:  
1. θ is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See  
JA  
Tech Brief TB379.  
Electrical Specifications  
V
= V = V  
IN  
= 3.3V, C1 = C2 = 10µF, L = 1.8µH, V = 1.8V (as shown in Typical Application Diagram),  
EN O  
DD  
unless otherwise specified.  
DESCRIPTION  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNIT  
DC CHARACTERISTICS  
V
Feedback Input Voltage  
PWM Mode  
790  
800  
810  
100  
5.5  
2.2  
2.4  
mV  
nA  
V
FB  
I
Feedback Input Current  
Input Voltage  
FB  
V
V
V
, V  
2.5  
2
IN DD  
IN,OFF  
IN,ON  
Minimum Voltage for Shutdown  
Maximum Voltage for Startup  
Input Supply Quiescent Current  
Active - PFM Mode  
V
V
falling  
rising  
V
IN  
IN  
2.2  
V
I
S
V
V
= 0V  
120  
6.5  
400  
0.1  
70  
145  
7.5  
500  
1
µA  
mA  
µA  
µA  
mΩ  
mΩ  
A
SYNC  
SYNC  
Active - PWM Mode  
= 3.3V  
I
Supply Current  
PWM, V = V  
IN DD  
= 5V  
= 5V  
DD  
EN = 0, V = V  
IN  
DD  
R
R
PMOS FET Resistance  
NMOS FET Resistance  
Current Limit  
V
= 5V, wafer test only  
= 5V, wafer test only  
100  
75  
DS(ON)-PMOS  
DS(ON)-NMOS  
LMAX  
DD  
DD  
V
45  
I
1.2  
145  
130  
T
Over-temperature Threshold  
Over-temperature Hysteresis  
EN, SYNC Current  
T rising  
T falling  
°C  
°C  
µA  
V
OT,OFF  
OT,ON  
T
I
, I  
EN SYNC  
V
V
V
V
V
, V  
EN RSI  
= 0V and 3.3V  
-1  
0.8  
86  
1
V
V
V
, V  
EN1 SYNC1  
EN, SYNC Rising Threshold  
EN, SYNC Falling Threshold  
= 3.3V  
= 3.3V  
rising  
2.4  
DD  
DD  
, V  
V
EN2 SYNC2  
Minimum V for PG, WRT Targeted  
FB  
95  
70  
%
PG  
FB  
V
Value  
FB  
falling  
%
FB  
V
PG Voltage Drop  
I
= 3.3mA  
35  
1.4  
650  
mV  
OLPG  
SINK  
AC CHARACTERISTICS  
F
PWM Switching Frequency  
Minimum SYNC Pulse Width  
Soft-start Time  
1.25  
25  
1.6  
MHz  
ns  
PWM  
SYNC  
SS  
t
t
Guaranteed by design  
µs  
FN7434.3  
2
August 10, 2005  
EL7530  
Pin Descriptions  
PIN NUMBER  
PIN NAME  
PIN FUNCTION  
1
2
3
4
5
6
SGND  
PGND  
LX  
Negative supply for the controller stage  
Negative supply for the power stage  
Inductor drive pin; high current digital output with average voltage equal to the regulator output voltage  
Positive supply for the power stage  
VIN  
VDD  
SYNC  
Power supply for the controller stage  
SYNC input pin; when connected to HI, regulator runs at forced PWM mode; when connected to Low, auto  
PFM/PWM mode; when connected to external sync signal, at external PWM frequency up to 12MHz  
7
8
EN  
PG  
VO  
FB  
Enable  
Power-Good open drain output  
Output voltage sense  
9
10  
Voltage feedback input; connected to an external resistor divider between V and SGND for variable  
O
output  
Block Diagram  
100Ω  
V
V
DD  
INDUCTOR SHORT  
O
0.1µF  
+
-
10pF  
V
IN  
C4 124K  
470pF  
CURRENT  
SENSE  
FB  
5M  
-
+
PWM  
COMPEN-  
SATION  
+
-
PWM  
COMPARATOR  
P-DRIVER  
100K  
1.8µH  
LX  
RAMP  
GENERA-  
TOR  
PFM  
ON-TIME  
CONTROL  
SYNC  
EN  
CONTROL  
LOGIC  
1.8V  
0 TO 600mA  
SYNC  
EN  
CLOCK  
SOFT-  
START  
+
-
10µF  
10µF  
PWM  
N-DRIVER  
COMPARATOR  
UNDER-  
VOLTAGE  
LOCKOUT  
+
5V  
PGND  
PG  
BANDGAP  
REFERENCE  
+
-
100K  
TEMPERA-  
TURE  
SENSE  
SYNCHRONOUS  
RECTIFIER  
PG  
SGND  
POWER  
GOOD  
FN7434.3  
3
August 10, 2005  
EL7530  
Performance Curves and Waveforms  
All waveforms are taken at V =3.3V, V =1.8V, I =600mA with component values shown on page 1 at room ambient temperature, unless  
IN  
O
O
otherwise noted.  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
45  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
V
=3.3V  
O
V
=3.3V  
O
V
=2.5V  
O
V
=2.5V  
O
V
=1.8V  
O
V
=1.8V  
O
V
=1.0V  
V
=1.5V  
O
O
V
=1.5V  
O
V
=1.2V  
O
V
=0.8V  
O
V
=1.0V  
O
V
=1.2V  
O
V
=0.8V  
O
V
=5V  
IN  
V
=5V  
IN  
40  
1
10  
100  
600  
1
10  
100  
600  
I
(mA)  
O
I
(mA)  
O
FIGURE 1. EFFICIENCY vs I (PFM/PWM MODE)  
FIGURE 2. EFFICIENCY vs I (PWM MODE)  
O
O
100  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
45  
40  
V
V
=2.5V  
=1.8V  
V
V
=2.5V  
=1.8V  
O
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
O
O
O
V
=1.5V  
O
V
=1.2V  
O
V
=1.5V  
O
V
=1.2V  
O
V
=1.0V  
O
V
=0.8V  
=1.0V  
O
V
O
V
=0.8V  
O
V
=3.3V  
IN  
V
=3.3V  
IN  
1
10  
100  
600  
1
10  
I
100  
600  
I
(mA)  
(mA)  
O
O
FIGURE 3. EFFICIENCY vs I (PFM/FWM MODE)  
O
FIGURE 4. EFFICIENCY vs I (PWM MODE)  
O
1.44  
0.1%  
V
=3.3V I =600mA  
IN  
O
V
=5V I =600mA  
O
IN  
V
=5V I =0A  
O
IN  
1.42  
1.4  
0.0%  
-0.1%  
V
=3.3V I =0A  
O
IN  
V
=3.3V  
IN  
1.38  
1.36  
1.34  
1.32  
-0.2%  
-0.3%  
-0.4%  
-0.5%  
V
=5V  
IN  
0
0.2  
0.4  
0.6  
0.8  
1
-50  
0
50  
100  
150  
T
(°C)  
I
(A)  
A
O
FIGURE 5. F vs JUNCTION TEMPERATURE (PWM MODE)  
S
FIGURE 6. LOAD REGULATIONS (PWM MODE)  
FN7434.3  
August 10, 2005  
4
EL7530  
Performance Curves and Waveforms (Continued)  
All waveforms are taken at V =3.3V, V =1.8V, I =600mA with component values shown on page 1 at room ambient temperature, unless  
IN  
O
O
otherwise noted.  
0.1%  
0.0%  
12  
10  
8
V
=5V I =0A  
IN  
O
V
=3.3V I =0A  
IN  
O
-0.1%  
-0.2%  
V
=3.3V I =600mA  
O
IN  
-0.3%  
-0.4%  
-0.5%  
6
4
2
0
-0.6%  
V
=5V I =600mA  
O
IN  
-0.7%  
-50  
0
50  
100  
150  
3.5  
4
4.5  
5
2.5  
3
T
(°C)  
V
(V)  
J
S
FIGURE 7. PWM MODE LOAD/LINE REGULATIONS vs  
JUNCTION TEMPERATURE  
FIGURE 8. NO LOAD QUIESCENT CURRENT (PWM MODE)  
140  
V
=3.3V  
O
130  
120  
110  
100  
V
=1.8V  
O
V
=1.5V  
O
V
=1.2V V =1.0V  
O
O
90  
V
=0.8V  
O
80  
70  
60  
50  
2.0  
2.5  
3.0  
3.5  
4.0  
(V)  
4.5  
5.0  
5.5  
6.0  
V
S
FIGURE 9. NO LOAD QUIESCENT CURRENT (PFM MODE)  
1
2
V
IN  
(2V/DIV)  
EN  
I
IN  
(0.25A/DIV)  
I
IN  
(0.25A/DIV)  
V
O
(2V/DIV)  
V
O
PG  
(2V/DIV)  
PG  
500µs/DIV  
200µs/DIV  
FIGURE 10. START-UP AT I = 600mA  
O
FIGURE 11. ENABLE AND SHUT-DOWN  
FN7434.3  
August 10, 2005  
5
EL7530  
Performance Curves and Waveforms (Continued)  
All waveforms are taken at V =3.3V, V =1.8V, I =600mA with component values shown on page 1 at room ambient temperature, unless  
IN  
O
O
otherwise noted.  
LX  
(2V/DIV)  
LX  
(2V/DIV)  
I
L
(0.5A/DIV)  
I
L
(0.5A/DIV)  
V  
O
V  
(10mV/DIV)  
O
(50mV/DIV)  
0.5µs/DIV  
2µs/DIV  
FIGURE 12. PFM STEADY-STATE OPERATION WAVEFORM  
(I = 100mA)  
FIGURE 13. PWM STEADY-STATE OPERATION (I = 600mA)  
O
O
SYNC  
(2V/DIV)  
SYNC  
(2V/DIV)  
LX  
(2V/DIV)  
LX  
(2V/DIV)  
I
L
(0.5A/DIV)  
I
L
(0.5A/DIV)  
20ns/DIV  
0.2µs/DIV  
FIGURE 15. EXTERNAL SYNCHRONIZATION TO 12MHz  
FIGURE 14. EXTERNAL SYNCHRONIZATION TO 2MHz  
I
O
I
O
(200mA/DIV)  
(200mA/DIV)  
V  
O
V  
O
(100mV/DIV)  
(100mV/DIV)  
50µs/DIV  
100µs/DIV  
FIGURE 17. PWM LOAD TRANSIENT RESPONSE (30mA TO  
600mA)  
FIGURE 16. LOAD TRANSIENT RESPONSE (22mA to 600mA)  
FN7434.3  
August 10, 2005  
6
EL7530  
Performance Curves and Waveforms (Continued)  
All waveforms are taken at V =3.3V, V =1.8V, I =600mA with component values shown on page 1 at room ambient temperature, unless  
IN  
O
O
otherwise noted.  
100  
80  
60  
40  
20  
0
1.4MHz  
12MHz  
5MHz  
I
O
(200mA/DIV)  
V  
O
(50mV/DIV)  
0
200  
400  
600  
(mA)  
800  
1K  
1.2K  
50µs/DIV  
I
O
FIGURE 19. EFFICIENCY vs I (PWM MODE)  
O
FIGURE 18. PWM LOAD TRANSIENT RESPONSE (100mA TO  
500mA)  
0.5  
0.3  
1
12MHz  
0.6  
12MHz  
1.4MHz  
0.1  
0.2  
1.4MHz  
-0.1  
5MHz  
0
5MHz  
1K  
-0.3  
-0.5  
-0.2  
-0.6  
0
200  
400  
600  
(V)  
800  
1.2K  
0
200  
400  
600  
(mA)  
800  
1K  
1.2K  
V
IN  
I
O
FIGURE 21. LINE REGULATION @ 500mA (PWM MODE)  
FIGURE 20. LOAD REGULATION (PWM MODE)  
I
=50mA  
I
=150mA  
O
O
SYNC  
(2V/DIV)  
SYNC  
(2V/DIV)  
LX  
(2V/DIV)  
LX  
(2V/DIV)  
2µs/DIV  
2µs/DIV  
FIGURE 22. PFM-PWM TRANSITION TIME  
FIGURE 23. PFM-PWM TRANSITION TIME  
FN7434.3  
August 10, 2005  
7
EL7530  
Performance Curves and Waveforms (Continued)  
All waveforms are taken at V =3.3V, V =1.8V, I =600mA with component values shown on page 1 at room ambient temperature, unless  
IN  
O
O
otherwise noted.  
3
2
1
0
-1  
-2  
-3  
PFM  
PWM  
600  
0
200  
400  
800  
1000  
1200  
I
(mA)  
OUT  
FIGURE 24. PFM-PWM LOAD REGULATION  
JEDEC JESD51-3 LOW EFFECTIVE THERMAL  
CONDUCTIVITY TEST BOARD  
JEDEC JESD51-7 HIGH EFFECTIVE THERMAL  
CONDUCTIVITY TEST BOARD  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
1
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
870mW  
486mW  
0
25  
50  
75 85 100  
125  
0
25  
50  
75 85 100  
125  
AMBIENT TEMPERATURE (°C)  
AMBIENT TEMPERATURE (°C)  
FIGURE 25. PACKAGE POWER DISSIPATION vs AMBIENT  
TEMPERATURE  
FIGURE 26. PACKAGE POWER DISSIPATION vs AMBIENT  
TEMPERATURE  
FN7434.3  
August 10, 2005  
8
EL7530  
and the output capacitor act as a low pass filter, the duty  
cycle ratio is approximately equal to V divided by V  
Applications Information  
Product Description  
The EL7530 is a synchronous, integrated FET 600mA step-  
down regulator which operates from an input of 2.5V to 5.5V.  
The output voltage is user-adjustable with a pair of external  
resistors.  
.
IN  
O
The output LC filter has a second order effect. To maintain  
the stability of the converter, the overall controller must be  
compensated. This is done with the fixed internally  
compensated error amplifier and the PWM compensator.  
Because the compensations are fixed, the values of input  
and output capacitors are 10µF to 22µF ceramic and  
inductor is 1.5µH to 2.2µH.  
When the load is very light, the regulator automatically  
operates in the PFM mode, thus achieving high efficiency at  
light load (>70% for 1mA load). When the load increases,  
the regulator automatically switches over to a voltage-mode  
PWM operating at nominal 1.4MHz switching frequency. The  
efficiency is up to 95%.  
Forced PWM Mode/SYNC Input  
Pulling the SYNC pin HI (>2.5V) forces the converter into  
PWM mode in the next switching cycle regardless of output  
current. The duration of the transition varies depending on  
the output current. Figures 22 and 23 (under two different  
loading conditions) show the device goes from PFM to PWM  
mode.  
It can also operate in a fixed PWM mode or be synchronized  
to an external clock up to 12MHz for improved EMI  
performance.  
PFM Operation  
The heart of the EL7530 regulator is the automatic  
PFM/PWM controller.  
Start-Up and Shut-Down  
When the EN pin is tied to V , and V reaches  
IN  
IN  
approximately 2.4V, the regulator begins to switch. The  
inductor current limit is gradually increased to ensure proper  
soft-start operation.  
If the SYNC pin is connected to ground, the regulator  
operates automatically in either the PFM or PWM mode,  
depending on load. When the SYNC pin is connected to V  
the regulator operates in the fixed PWM mode. When the pin  
is connected to an external clock ranging from 1.6MHz to  
12MHz, the regulator is in the fixed PWM mode and  
synchronized to the external clock frequency.  
,
IN  
When the EN pin is connected to a logic low, the EL7530 is  
in the shut-down mode. All the control circuitry and both  
MOSFETs are off, and V  
falls to zero. In this mode, the  
OUT  
total input current is less than 1µA.  
When the EN reaches logic HI, the regulator repeats the  
start-up procedure, including the soft-start function.  
In the automatic PFM/PWM operation, when the load is light,  
the regulator operates in the PFM mode to achieve high  
efficiency. The top P channel MOSFET is turned on first. The  
inductor current increases linearly to a preset value before it  
is turned off. Then the bottom N channel MOSFET turns on,  
and the inductor current linearly decreases to zero current.  
The N channel MOSFET is then turned off, and an anti-  
ringing MOSFET is turned on to clamp the VLX pin to VO.  
The inductor current looks like triangular pulses. The  
Current Limit and Short-Circuit Protection  
The current limit is set at about 1.2A for the PMOS. When a  
short-circuit occurs in the load, the preset current limit  
restricts the amount of current available to the output, which  
causes the output voltage to drop below the preset voltage.  
In the meantime, the excessive current heats up the  
regulator until it reaches the thermal shut-down point.  
frequency of the pulses is mainly a function of output current.  
The higher the load, the higher the frequency of the pulses  
until the inductor current becomes continuous. At this point,  
the controller automatically changes to PWM operation.  
Thermal Shut-Down  
Once the junction reaches about 145°C, the regulator shuts  
down. Both the P channel and the N channel MOSFETs turn  
off. The output voltage will drop to zero. With the output  
MOSFETs turned off, the regulator will soon cool down.  
Once the junction temperature drops to about 130°C, the  
regulator will restart again in the same manner as EN pin  
connects to logic HI.  
PWM Operation  
The regulator operates the same way in the forced PWM or  
synchronized PWM mode. In this mode, the inductor current  
is always continuous and does not stay at zero.  
In this mode, the P channel MOSFET and N channel  
MOSFET always operate complementary. When the  
PMOSFET is on and the NMOSFET off, the inductor current  
increases linearly. The input energy is transferred to the  
output and also stored in the inductor. When the P channel  
MOSFET is off and the N channel MOSFET on, the inductor  
current decreases linearly, and energy is transferred from  
the inductor to the output. Hence, the average current  
through the inductor is the output current. Since the inductor  
Thermal Performance  
The EL7530 is available in a fused-lead MSOP10.  
Compared with regular MSOP10 package, the fused- lead  
package provides lower thermal resistance. The θ is  
100°C/W on a 4-layer board and 125°C/W on 2-layer board.  
Maximizing the copper area around the pins will further  
improve the thermal performance.  
JA  
FN7434.3  
9
August 10, 2005  
EL7530  
Output Voltage Selection  
Users can set the output voltage of the variable version with  
a resister divider, which can be chosen based on the  
following formula:  
Layout Considerations  
The layout is very important for the converter to function  
properly. The following PC layout guidelines should be  
followed:  
R
R
2
1. Separate the Power Ground ( ) and Signal Ground  
V
= 0.8 × 1 + ------  
O
(
i); connect them only at one point right at the pins  
1
2. Place the input capacitor as close to V and PGND pins  
IN  
Component Selection  
as possible  
Because of the fixed internal compensation, the component  
choice is relatively narrow. For a regulator with fixed output  
voltage, only two capacitors and one inductor are required.  
We recommend 10µf to 22µF multi-layer ceramic capacitors  
with X5R or X7R rating for both the input and output  
capacitors, and 1.5µH to 2.2µH for the inductor.  
3. Make the following PC traces as small as possible:  
4. from LX pin to L  
5. from C to PGND  
O
6. If used, connect the trace from the FB pin to R and R  
1
2
as close as possible  
7. Maximize the copper area around the PGND pin  
The RMS current present at the input capacitor is decided by  
the following formula:  
8. Place several via holes under the chip to additional  
ground plane to improve heat dissipation  
The demo board is a good example of layout based on this  
outline. Please refer to the EL7530 Application Brief.  
V
× (V V  
)
O
IN  
O
-----------------------------------------------  
I
=
× I  
INRMS  
O
V
IN  
This is about half of the output current I for all the V . This  
O
O
input capacitor must be able to handle this current.  
The inductor peak-to-peak ripple current is given as:  
(V V ) × V  
O
IN  
O
I = -------------------------------------------  
IL  
L × V × f  
IN  
S
L is the inductance  
the switching frequency (nominally 1.4MHz)  
f
S
The inductor must be able to handle I for the RMS load  
O
current, and to assure that the inductor is reliable, it must  
handle the 2A surge current that can occur during a current  
limit condition.  
FN7434.3  
10  
August 10, 2005  
EL7530  
MSOP Package Outline Drawing  
NOTE: The package drawing shown here may not be the latest version. To check the latest revision, please refer to the Intersil website at  
<http://www.intersil.com/design/packages/index.asp>  
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  
FN7434.3  
11  
August 10, 2005  

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