Datasheet
LTC3714
1
3714f
Typical applicaTion
FeaTures DescripTion
Intel Compatible,
Wide Operating Range, Step-Down Controller
with Internal Op Amp
The LTC
®
3714 is a synchronous step-down switching
regulator controller for CPU power. An output voltage
between 0.6V and 1.75V is selected by a 5-bit code (Intel
mobile VID specification). The controller uses a constant
on-time, valley current control architecture to deliver very
low duty cycles without requiring a sense resistor. Oper-
ating frequency is selected by an external resistor and is
compensated for variations in V
IN
and V
OUT
.
Discontinuous mode operation provides high efficiency
operation at light loads. A forced continuous control pin
reduces noise and RF interference and can assist second-
ary winding regulation by disabling discontinuous mode
when the main output is lightly loaded. Internal op amp
allows programmable offsets to the output voltage during
power saving modes.
Fault protection is provided by internal foldback current
limiting, an output overvoltage comparator and optional
short-circuit shutdown timer. Soft-start capability for
supply sequencing is accomplished using an external
timing capacitor. The regulator current limit level is user
programmable. Wide supply range allows operation from
4V to 36V at the input.
L, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corporation.
applicaTions
n
True Current Mode with Ultrafast Transient Response
n
Stable with Ceramic C
OUT
n
t
ON(MIN)
< 100ns for Operation from High Input
Ranges
n
Supports Active Voltage Positioning
n
No Sense Resistor Required
n
5-Bit VID Programmable Output Voltage: 0.6V to 1.75V
n
Dual N-Channel MOSFET Synchronous Drive
n
Programmable Output Offsets
n
Power Good Output Voltage Monitor
n
Wide V
IN
Range: 4V to 36V
n
±1% 0.6V Reference
n
Adjustable Frequency
n
Programmable Soft-Start
n
Output Overvoltage Protection
n
Optional Short-Circuit Shutdown Timer
n
Forced Continuous Control Pin
n
Logic Controlled Micropower Shutdown: I
Q
≤ 30µA
n
Available in 0.209" Wide 28-Lead SSOP Package
n
Power Supply for Mobile Pentium
®
Processors and
Transmeta Processors
n
Notebook and Portable Computers
Figure 1. High Efficiency Step-Down Converter
Transient Response of 8A to 23A Output Load Step
+
D
B
CMDSH-3
D1*
UPS840
*OPTIONAL
L1
0.68µH
C
VCC
4.7µF
10µF
35V
×4
V
IN
5V TO 24V
V
OUT
0.6V TO 1.75V
23A
+
C
OUT
270µF
2V
×4
M2
IRF7811
×3
0.003Ω*
3714 F01
M1
IRF7811
×2
R
ON
C
SS
0.1µF
INTV
CC
I
ON
V
IN
TG
SW
BOOST
RUN/SS
I
TH
SGND
INTV
CC
BG
PGND
SENSE
5-BIT
VID
V
OSENSE
PGOOD
VID0
VID1
VID2
VID3
VID4
C
B
, 0.22µF
R
C
LTC3714
C
C
3714 TA03
1.395V
V
OUT
1.35V
50mV/DIV
1.213V
23A
8A
I
LOAD
10A/DIV
20µs/DIV