EL7551C - Preliminary
EL7551C - Preliminary
Monolithic 1 Amp DC:DC Step-down Regulator
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
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 in
2
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.
Applications
•
•
•
•
•
DSP, CPU Core and IO Supplies
Logic/Bus Supplies
Portable Equipment
DC:DC Converter Modules
GTL + Bus Power Supply
Typical Application Diagram
C3
C4
1 SGND
2 COSC
3 VDD
4 PGND
PGND 16
C5
VREF 15
0.1µF
FB 14
VDRV 13
LX 12
LX 11
VHI 10
PGND 9
C6
0.1µF
R1
1kΩ
L1
R2
2.37k
Ordering Information
Part No
EL7551CU
Package
16-Pin QSOP
Tape & Reel
Outline #
MDP0040
0.1µF 270pF
R3
39Ω
C1
10µF
ceramic
V
IN
(4.5V-
5.5V)
5 PGND
6 VIN
7 VIN
8 EN
10µH
C
7
V
O
47µF (3.3V,
1A)
October 3, 2001
EL7551C
Manufactured under U.S. Patent No. 57,323,974
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.
ELANTEC [ ELANTEC SEMICONDUCTOR ]
