1
FN7003.2
EL7535
Monolithic 350mA Step-Down Regulator
The EL7535 is a synchronous, integrated FET 350mA step-
down regulator in a MSOP10 package. The regulator is
internally compensated, which makes it possible to use just
five tiny external components to form a complete DC/DC
converter. The regulator operates with an input voltage
range from 2.5V to 6V, which accommodates supplies of
3.3V, 5V, or a Li-Ion battery source. The output can be
externally set from 0.8V to V
IN
with a resistive divider.
The EL7535 features PWM mode control. The operating
frequency is typically 1.4MHz. Additional features include
<1A shut-down current, short-circuit protection, and over-
temperature protection.
The EL7535 is available in the 10-pin MSOP package and is
specified for operation over the full -40C to +85C
temperature range.
Features
Extremely small 350mA DC/DC converter
Max height 1.1mm MSOP10 package
Possibly uses only five tiny external components with fixed
output
Power-On-Reset output (POR)
Internally-compensated voltage mode controller
Up to 94% efficiency
<1A shut-down current
Overcurrent and over-temperature protection
Pb-Free plus anneal available (RoHS compliant)
Applications
PDA and pocket PC computers
Bar code readers
Cellular phones
Portable test equipment
Li-Ion battery powered devices
Small form factor (SFP) modules
Pinout and Typical Application Diagram
EL7535
(10-PIN MSOP)
TOP VIEW
Ordering Information
PART NUMBER
(BRAND)
PACKAGE
TAPE &
REEL
PKG.
DWG. #
EL7535IY
(a)
10-Pin MSOP
-
MDP0043
EL7535IY-T7
(a)
10-Pin MSOP
7"
MDP0043
EL7535IY-T13
(a)
10-Pin MSOP
13"
MDP0043
EL7535IYZ
(BAACA) (Note)
10-Pin MSOP
(Pb-free)
-
MDP0043
EL7535IYZ-T7
(BAACA) (Note)
10-Pin MSOP
(Pb-free)
7"
MDP0043
EL7535IYZ-T13
(BAACA) (Note)
10-Pin MSOP
(Pb-free)
13"
MDP0043
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.
* FOR VARIABLE OUTPUT VOLTAGE: V
O
= 0.8V * (1 + R
2
/ R
1
)
SGND
FB
VDD
RSI
VIN
EN
LX
POR
PGND
VO
1.8H
V
O
(1.8V@350mA)
C
1
POR
R
2
*
R
1
*
124k
100k
EN
RSI
100k
C
2
V
IN
(2.5V-6V)
100k
R
4
R
5
10F
10F
L
1
R
6
100k
1
2
3
4
10
9
8
7
5
6
Data Sheet
August 16, 2005
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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.
2
FN7003.2
August 16, 2005
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
J
= T
C
= T
A
Absolute Maximum Ratings
(T
A
= 25C)
V
IN
, V
DD
, POR to SGND . . . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V
LX to PGND . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (V
IN
+ +0.3V)
RSI, EN, V
O
, FB to SGND . . . . . . . . . . . . . . . -0.3V to (V
IN
+ +0.3V)
PGND to SGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +0.3V
Peak Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500mA
Operating Ambient Temperature . . . . . . . . . . . . . . . .-40C to +85C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65C to +150C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +145C
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.
Electrical Specifications
V
DD
= V
IN
= V
EN
= 3.3V, C1 = C2 = 10F, L = 1.8H, V
O
= 1.8V, unless otherwise specified.
PARAMETER
DESCRIPTION
CONDITIONS
MIN
TYP
MAX
UNIT
DC CHARACTERISTICS
V
FB
Feedback Input Voltage
790
800
810
mV
I
FB
Feedback Input Current
250
nA
V
IN
, V
DD
Input Voltage
2.5
6
V
V
IN,OFF
Minimum Voltage for Shutdown
V
IN
falling
2
2.2
V
V
IN,ON
Maximum Voltage for Startup
V
IN
rising
2.2
2.4
V
I
DD
Supply Current
PWM, V
IN
= V
DD
= 5V
400
500
A
EN = 0, V
IN
= V
DD
= 5V
0.1
1
A
R
DS(ON)-PMOS
PMOS FET Resistance
V
DD
= 5V, wafer test only
70
100
m
R
DS(ON)-NMOS
NMOS FET Resistance
V
DD
= 5V, wafer test only
45
75
m
I
LMAX
Current Limit
1.5
A
T
OT,OFF
Over-temperature Threshold
T rising
145
C
T
OT,ON
Over-temperature Hysteresis
T falling
130
C
I
EN
, I
RSI
EN, RSI Current
V
EN
, V
RSI
= 0V and 3.3V
-1
1
A
V
EN1
, V
RSI1
EN, RSI Rising Threshold
V
DD
= 3.3V
2.4
V
V
EN2
, V
RSI2
EN, RSI Falling Threshold
V
DD
= 3.3V
0.8
V
V
POR
Minimum V
FB
for POR, WRT Targeted
V
FB
Value
V
FB
rising
95
%
V
FB
falling
86
%
V
OLPOR
POR Voltage Drop
I
SINK
= 5mA
35
70
mV
AC CHARACTERISTICS
F
PWM
PWM Switching Frequency
1.25
1.4
1.55
MHz
t
RSI
Minimum RSI Pulse Width
Guaranteed by design
25
50
ns
t
SS
Soft-start Time
650
s
t
POR
Power On Reset Delay Time
80
100
120
ms
EL7535
3
FN7003.2
August 16, 2005
Timing Diagram
Pin Descriptions
PIN NUMBER
PIN NAME
PIN FUNCTION
1
SGND
Negative supply for the controller stage
2
PGND
Negative supply for the power stage
3
LX
Inductor drive pin; high current digital output with average voltage equal to the regulator output voltage
4
VIN
Positive supply for the power stage
5
VDD
Power supply for the controller stage
6
RSI
Resets POR timer
7
EN
Enable
8
POR
Power on reset open drain output
9
VO
Output voltage sense
10
FB
Voltage feedback input; connected to an external resistor divider between V
O
and SGND for variable
output
100ms
MIN
25ns
100ms
POR
RSI
V
O
EL7535
4
FN7003.2
August 16, 2005
Block Diagram
-
+
-
+
-
+
CONTROL
LOGIC
PWM
COMPEN-
SATION
UNDER-
VOLTAGE
LOCKOUT
POR
CLOCK
1.4MHz
SOFT-
START
BANDGAP
REFERENCE
TEMPERATURE
SENSE
+
V
IN
LX
PGND
POR
V
O
FB
EN
V
DD
SGND
10pF
5M
124K
100K
10F
5V
EN
PWM
COMPARATOR
N-DRIVER
P-DRIVER
CURRENT
LIMIT
1.8
10F
100K
PG
1.8V
350mA
RSI
RAMP
GENERATOR
EL7535
5
FN7003.2
August 16, 2005
Typical Performance Curves
FIGURE 1. EFFICIENCY
FIGURE 2. EFFICIENCY
FIGURE 3. PACKAGE POWER DISSIPATION vs AMBIENT
TEMPERATURE
FIGURE 4. PACKAGE POWER DISSIPATION vs AMBIENT
TEMPERATURE
100
95
90
85
80
75
70
65
60
0
200
400
I
O
(mA)
E
F
FICIE
NCY (
%
)
V
O
=3.3V
V
O
=1.2V
300
100
V
O
=2.5V
V
O
=1.8V
V
IN
=5V
100
95
90
85
80
75
70
65
60
0
I
O
(mA)
E
F
FICIE
NCY (
%
)
V
O
=2.5V
V
O
=1V
200
400
300
100
V
O
=1.2V
V
O
=1.8V
V
IN
=3.3V
JEDEC JESD51-7 HIGH EFFECTIVE THERMAL
CONDUCTIVITY TEST BOARD
1.2
1
0.4
0
0
25
50
75
100
150
AMBIENT TEMPERATURE (C)
POWE
R DI
SSI
PATI
ON
(W)
85
1.087W
JA
=11
5C
/W
MS
OP
8/1
0
0.8
0.2
0.6
125
JEDEC JESD51-3 LOW EFFECTIVE THERMAL
CONDUCTIVITY TEST BOARD
0.7
0.6
0.4
0.3
0.2
0.1
0
0
25
50
75
100
150
AMBIENT TEMPERATURE (C)
POWE
R DI
SSI
PATI
ON
(W)
85
607mW
JA
=20
6C
/W
MS
OP
8/1
0
0.5
125
Waveforms
All waveforms are taken at V
IN
=3.3V, V
O
=1.8V, I
O
=350mA with component values shown on page 1, unless otherwise noted
FIGURE 5. START-UP 1
FIGURE 6. START-UP 2
V
IN
(1V/DIV)
I
IN
(0.2A/DIV)
V
O
(1V/DIV)
0.5ms/DIV
V
IN
(2V/DIV)
POR
(2V/DIV)
V
O
(2V/DIV)
50ms/DIV
EL7535
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