EL7556BC
EL7556BC
Integrated Adjustable 6 Amp Synchronous Switcher
Features
• EL7556C/EL7556AC Pin-
compatible
• Improved temperature and voltage
ranges
• 6A continuous load current
• Precision internal 1% reference
• 1.0V to 3.8V output voltage
• Internal power MOSFETs
• >90% efficiency
• Synchronous switching
• Adjustable slope compensation
• Over-temperature indicator
• Pulse-by-pulse current limiting
• Operates up to 1MHz
• 1.5% typical output accuracy
• Adjustable oscillator with sync
• Remote enable/disable
• Intel P54- and P55-compatible
• VCC2DET interface
• Internal soft-start
General Description
The EL7556BC is an adjustable synchronous DC:DC switching regu-
lator optimized for a 5V input and 1.0V-3.8V output. By combining
integrated NMOS power FETS with a fused-lead package, the
EL7556BC can supply up to 6A continuous output current without the
use of external power devices or discrete heat sinks, thereby minimiz-
ing design effort and overall system cost.
On-chip resistorless current sensing is used to achieve stable, highly
efficient, current-mode control. The EL7556BC also incorporates the
VCC2DET function to directly interface with the Intel P54 and P55
microprocessors. Depending on the state of VCC2DET, the output
voltage is internally preset to 3.5V or a user-adjustable voltage using
two external resistors. In both internal and external feedback modes
the active-high PWRGD output indicates when the regulator output is
within ±10% of the programmed voltage. An on-board sensor moni-
tors die temperature (OT) for over-temperature conditions and can be
connected directly to OUTEN to provide automatic thermal shutdown.
Adjustable oscillator frequency and slope compensation allow added
flexibility in overall system design.
The EL7556BC is available in a 28-pin SO package and is specified
for operation over the full -40°C to +85°C temperature range.
Applications
•
•
•
•
•
•
PC motherboards
Local high power CPU supplies
5V to 1.0V DC:DC conversion
Portable electronics/instruments
P54 and P55 regulators
GTL+ Bus power supply
Connection Diagram
R4
R3
100Ω
150Ω
V
IN
D3
1
C4
0.1µF
2
C7
39pF
3
C8
R5
5
5.1Ω
6
220pF
4
FB1
CREF
CSLOPE
COSC
VDD
VIN
VSSP
VIN
VSSP
FB2
28
CP
C2V
VSS
27
R1
26
20Ω
25
R6
VHI
24
C6
LX
LX
LX
LX
VSSP
VSSP
TEST
23
0.1µF
22
21
20
19
18
17
L1
2.5µH
C10
1mF
39.2Ω
D1
C11
0.22µF
C5
1µF
D2
D4*
(Optional)
Ordering Information
Part No
EL7556BCM
EL7556BCM-T13
Package
28-Pin SO
28-Pin SO
Tape &
Reel
-
13”
Outline #
MDP0027
MDP0027
7
C9
C12
1µF
C3
1µF
8
9
V
OUT =
1V*(1+R3/R4)
V
IN
660µF
10
VSSP
11
VSSP
12
VSSP
Connect to VSSP for
external feedback
13
October 5, 2001
VCC2DET
16
PWRGD
OT
15
14
OUTEN
EL7556BC
C12 - 1µF
C3, C4, C5, C6, C7 C8 - ceramic
C5, C11 - ceramic or tantalum
C9 - Sprague 293D337X96R3 2X330µF
C10 - Sprague 293D337X96R3 3X330µF
L1 - Pulse Engineering, PE-53681
D1-D4: BAT54S fast diode
D4 Required for EL7556ACM Only
Manufactured under U.S. Patents No. 5,723,974 and No. 5,793,126
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 ]
