EL7531IL-T13 [RENESAS]
1.2A SWITCHING REGULATOR, 1600kHz SWITCHING FREQ-MAX, PDSO10, MO-220, DFN-10;
| 型号： | EL7531IL-T13 |
| 厂家： | 
RENESAS TECHNOLOGY CORP |
| 描述： | 1.2A SWITCHING REGULATOR, 1600kHz SWITCHING FREQ-MAX, PDSO10, MO-220, DFN-10 开关 光电二极管 |
| 文件： | 总10页 (文件大小：733K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EL7531
®
Data Sheet
January 9, 2004
FN7428.1
PRELIMINARY
Monolithic 1A Step-Down Regulator with
Low Quiescent Current
Features
2
2
• Less than 0.15 in (0.97 cm ) footprint for the complete 1A
converter
The EL7531 is a synchronous,
integrated FET 1A step-down
• Components on one side of PCB
• Max height 1.1mm MSOP10 or 1mm DFN 10 package
• Power-Good (PG) output
regulator with internal compensation.
It operates with an input voltage range from 2.5V to 5.5V,
which accommodates supplies of 3.3V, 5V, or a Li-Ion
battery source. The output can be externally set from 0.8V to
• Internally-compensated voltage mode controller
• Up to 94% efficiency
V
with a resistive divider.
IN
The EL7531 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
• Over-current and over-temperature protection
• External synchronizable up to 12MHz
The EL7531 is available in the 10-pin MSOP and 10-pin
DFN (3x3 mm) packages, making the the entire converter
Applications
• PDA and pocket PC computers
2
occupy less than 0.15 in of PCB area with components on
one side only. Both packages are specified for operation
over the full -40°C to +85°C temperature range.
• Bar code readers
• Cellular phones
Ordering Information
• Portable test equipment
• Li-Ion battery powered devices
• Small form factor (SFP) modules
PART
NUMBER
PACKAGE
10-Pin MSOP
10-Pin MSOP
10-Pin MSOP
10-Pin DFN
10-Pin DFN
10-Pin DFN
TAPE & REEL PKG. DWG. #
EL7531IY
-
MDP0043
MDP0043
MDP0043
MDP0047
MDP0047
MDP0047
EL7531IY-T7
EL7531IY-T13
EL7531IL
7”
Pinout and Typical Application Diagram
EL7531
13”
-
TOP VIEW
EL7531IL-T7
EL7531IL-T13
7”
13”
R *
1
100kΩ
1
2
3
4
5
SGND
PGND
LX
FB 10
R *
2
124kΩ
VO
POR
EN
9
8
7
6
C
10µF
C
2
10µF
1
L
1
PG
1.8µH
V
V
(1.8V@1A)
O
VIN
EN
R
100Ω
3
(2.5V-6V)
S
VDD
RSI
SYNC
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 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2004. All Rights Reserved. Elantec is a registered trademark of Elantec Semiconductor, Inc.
All other trademarks mentioned are the property of their respective owners.
EL7531
Absolute Maximum Ratings (T = 25°C)
A
V
, V , PG to SGND . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V
Operating Ambient Temperature . . . . . . . . . . . . . . . .-40°C to +85°C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +145°C
IN DD
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2A
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
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
790
800
810
250
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
140
8
µA
mA
µA
µA
mΩ
mΩ
A
SYNC
SYNC
Active - PWM Mode
= 3.3V
I
Supply Current
PWM, V = V
IN DD
= 5V
= 5V
500
1
DD
EN = 0, V = V
IN
DD
R
R
PMOS FET Resistance
NMOS FET Resistance
Current Limit
V
V
= 5V, wafer test only
= 5V, wafer test only
100
75
DS(ON)-PMOS
DS(ON)-NMOS
LMAX
DD
DD
45
I
1.5
145
130
T
T
Over-temperature Threshold
Over-temperature Hysteresis
EN, SYNC Current
T rising
T falling
°C
°C
µA
V
OT,OFF
OT,ON
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
= 5mA
35
1.4
650
mV
OLPG
SINK
AC CHARACTERISTICS
F
PWM Switching Frequency
Minimum SYNC Pulse Width
Soft-start Time
1.25
25
1.55
MHz
ns
PWM
SYNC
SS
t
t
Guaranteed by design
µs
2
EL7531
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
-
124K
CURRENT
SENSE
FB
5M
-
PWM
+
+
COMPENSATION
-
PWM
P-DRIVER
100K
COMPARATOR
1.8µH
LX
PFM
SYNC
EN
RAMP
CONTROL
LOGIC
3.3V
SYNC
EN
CLOCK
ON-TIME
CONTROL
GENERATOR
0 TO 1A
SOFT-
+
START
-
10µF
10µF
PWM
N-DRIVER
COMPARATOR
UNDER-
VOLTAGE
LOCKOUT
+
PGND
PG
5V
–
BANDGAP
+
-
REFERENCE
100K
PG
TEMPERATURE
SENSE
SYNCHRONOUS
RECTIFIER
SGND
POWER
GOOD
3
EL7531
Performance Curves and Waveforms
All waveforms are taken at V =3.3V, V =1.8V, I =1A with component values shown on page 1 at room ambient temperature, unless otherwise
IN
O
O
noted.
100
90
80
70
60
50
40
30
20
10
0
100
95
90
85
80
75
70
65
60
55
50
45
40
V
=3.3V
O
V
=3.3V
O
V
=2.5V
O
V
=2.5V
O
V
=1.8V
O
V
=1.8V
V =1.5V
O
O
V
=1.0V
O
V
=1.5V
O
V
=1.2V
O
V
=1.0V
V
=0.8V
O
O
V
=1.2V
O
V
=0.8V
O
V
=5V
IN
V
=5V
IN
0.001
0.010
0.100
1.000
0.001
0.010
0.100
1.000
I
(A)
I
(A)
O
O
FIGURE 2. EFFICIENCY vs I (PWM MODE)
O
FIGURE 1. EFFICIENCY vs I (PFM/FWM MODE)
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
=1.0V
O
V
=0.8V
O
V
=0.8V
(A)
O
V
=3.3V
IN
V
=3.3V
IN
0.001
0.010
0.100
1.000
0.001
0.010
0.100
1.000
I
I
(A)
O
O
FIGURE 3. EFFICIENCY vs I (PFM/FWM MODE)
O
FIGURE 4. EFFICIENCY vs I (PWM MODE)
O
0.1%
1.44
V
=3.3V I =1A
IN
O
V
=5V I =1A
O
IN
V
=5V I =0A
O
0.0%
IN
1.42
1.4
-0.1%
V
=3.3V I =0A
O
IN
V
=3.3V
IN
-0.2%
-0.3%
-0.4%
-0.5%
1.38
1.36
1.34
1.32
V
=5V
IN
0
0.2
0.4
0.6
0.8
1
-50
0
50
100
150
I
(A)
T
(°C)
O
A
FIGURE 6. LOAD REGULATIONS (PWM MODE)
FIGURE 5. F vs JUNCTION TEMPERATURE (PWM MODE)
S
4
EL7531
Performance Curves and Waveforms (Continued)
All waveforms are taken at V =3.3V, V =1.8V, I =1A with component values shown on page 1 at room ambient temperature, unless otherwise
IN
O
O
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%
-0.3%
-0.4%
-0.5%
6
4
2
0
V
=3.3V I =1A
O
IN
V
=5V I =1A
O
-0.6%
-0.7%
IN
-50
0
50
100
150
3.5
4
4.5
5
2.5
3
T
(°C)
V
(V)
J
S
FIGURE 8. NO LOAD QUIESCENT CURRENT (PWM MODE)
FIGURE 7. PWM MODE LOAD/LINE REGULATIONS vs
JUNCTION TEMPERATURE
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)
V
IN
(2V/DIV)
EN
I
IN
(0.5A/DIV)
I
IN
(0.5A/DIV)
V
O
(2V/DIV)
V
O
PG
(2V/DIV)
PG
500µs/DIV
200µs/DIV
FIGURE 11. ENABLE AND SHUT-DOWN
FIGURE 10. START-UP AT I = 1A
O
5
EL7531
Performance Curves and Waveforms (Continued)
All waveforms are taken at V =3.3V, V =1.8V, I =1A with component values shown on page 1 at room ambient temperature, unless otherwise
IN
O
O
noted.
LX
(2V/DIV)
LX
(2V/DIV)
I
L
I
(0.5A/DIV)
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 = 1A)
O
O
SYNC
(2V/DIV)
SYNC
(2V/DIV)
LX
(2V/DIV)
LX
(2V/DIV)
I
L
I
L
(0.5A/DIV)
(0.5A/DIV)
20ns/DIV
0.2µs/DIV
FIGURE 15. EXTERNAL SYNCHRONIZATION TO 12MHz
FIGURE 14. EXTERNAL SYNCHRONIZATION TO 2MHz
I
O
I
O
(0.5A/DIV)
(0.5A/DIV)
∆V
O
∆V
O
(100mV/DIV)
(100mV/DIV)
50µs/DIV
100µs/DIV
FIGURE 17. PWM LOAD TRANSIENT RESPONSE (0A TO 1A)
FIGURE 16. LOAD TRANSIENT RESPONSE (22mA to 1A)
6
EL7531
Performance Curves and Waveforms (Continued)
All waveforms are taken at V =3.3V, V =1.8V, I =1A with component values shown on page 1 at room ambient temperature, unless otherwise
IN
O
O
noted.
I
O
(0.5A/DIV)
∆V
O
(100mV/DIV)
50µs/DIV
FIGURE 18. PWM LOAD TRANSIENT RESPONSE (0.25A TO 0.75A)
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
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.
Applications Information
Product Description
The EL7531 is a synchronous, integrated FET 1A 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.
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.
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 94%.
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
and the output capacitor act as a low pass filter, the duty
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 EL7531 regulator is the automatic
PFM/PWM controller.
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.
cycle ratio is approximately equal to V divided by V
.
O
IN
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.
,
IN
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.
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
7
EL7531
inductor current limit is gradually increased to ensure proper
soft-start operation.
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 1.5 to 2.2µH for the inductor.
When the EN pin is connected to a logic low, the EL7531 is
in the shut-down mode. All the control circuitry and both
MOSFETs are off, and V
falls to zero. In this mode, the
The RMS current present at the input capacitor is decided by
the following formula:
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.
V
× (V – V
)
O
IN
O
-----------------------------------------------
I
=
× I
INRMS
O
V
IN
Current Limit and Short-Circuit Protection
This is about half of the output current I for all the V . This
O
O
The current limit is set at about 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.
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
Thermal Shut-Down
L is the inductance
the switching frequency (nominally 1.4MHz)
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.
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.
Layout Considerations
The layout is very important for the converter to function
properly. The following PC layout guidelines should be
followed:
Thermal Performance
The EL7531 is available in a fused-lead MSOP10 or DFN-10
package. Compared with regular MSOP10 package, the
fused- lead package provides lower thermal resistance. The
1. Separate the Power Ground ( ) and Signal Ground
θ
is 100°C/W on a 4-layer board and 125°C/W on 2-layer
(
i); connect them only at one point right at the pins
JA
board. Maximizing the copper area around the pins will
further improve the thermal performance.
2. Place the input capacitor as close to V and PGND pins
IN
as possible
3. Make the following PC traces as small as possible:
4. from LX pin to L
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:
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
R
R
2
V
= 0.8 × 1 + ------
O
7. Maximize the copper area around the PGND pin
1
8. Place several via holes under the chip to additional
ground plane to improve heat dissipation
Component Selection
Because of the fixed internal compensation, the component
choice is relatively narrow. For a regulator with fixed output
The demo board is a good example of layout based on this
outline. Please refer to the EL7531 Application Brief.
8
EL7531
MSOP Package Outline Drawing
9
EL7531
DFN 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
10
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