
Note: All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication; however, this data sheet cannot be a “controlled document”. Current revisions, if any, to these
specifications are maintained at the factory and are available upon your request. We recommend checking the revision level before finalization of your design documentation.
2001 Elantec Semiconductor, Inc.
E
L
75
51
C
-
P
re
lim
in
ar
y
General Description
The EL7551C 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 EL7551C operates
at a constant frequency pulse width modulation (PWM) mode, making
external synchronization possible. Patented on-chip resistorless cur-
rent sensing enables current mode control, which provides cycle-by-
cycle current limiting, over-current protection, and excellent step load
response. The EL7551C 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 EL7551C ideal for desktop and portable
applications.
The EL7551C is specified for operation over the -40°C to +85°C tem-
perature range.
Typical Application Diagram
Manufactured under U.S. Patent No. 57,323,974
1
2
3
4
16
15
14
13
5
6
7
12
11
10
8
9
SGND
COSC
VDD
PGND
VIN
EN
PGND
VREF
FB
VDRV
LX
VHI
PGND
R3
R2
L1
C3
C4
C1
C5
R1
C6
C7
VO
(3.3V,
1A)
VIN
(4.5V-
5.5V)
2.37k
10H
1k
0.1F
47F
0.1F
0.1F 270pF
39
10F
ceramic
EL7551C
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
1MHz
Oscillator synchronization
possible
Internal soft start
Over temperature protection
Under voltage lockout
16-pin QSOP package
Applications
DSP, CPU Core and IO Supplies
Logic/Bus Supplies
Portable Equipment
DC:DC Converter Modules
GTL + Bus Power Supply
Ordering Information
Part No
Package
Tape & Reel
Outline #
EL7551CU
16-Pin QSOP
MDP0040
EL7551C - Preliminary
Monolithic 1 Amp DC:DC Step-down Regulator
O
ct
ob
er
3,
20
01