LTC1705_15 Datasheet, PDF (1/28 Pages) Linear Technology – Dual 550kHz Synchronous Switching Regulator Controller with 5-Bit VID and 150mA LDO

LTC1705
FEATURES
Dual 550kHz Synchronous
Switching Regulator Controller with
5-Bit VID and 150mA LDO
DESCRIPTIO
s _{Three Regulated Outputs: Core, I/O and CLK in One}
Package
s _{Integrated Intel Mobile 5-Bit VID DAC}
s _{No External Current Sense Resistors}
s _{All N-Channel External MOSFET Architecture}
s _{550kHz Switching Frequency Minimizes External}
Component Size and Cost
s _{Integrated 150mA LDO Linear Regulator}
s _{Excellent DC Accuracy: 1.25% for Core, 2% for I/O}
and CLK Supplies
s _{PGOOD Flag Monitors All Three Outputs}
s _{High Efficiency Over Wide Load Current Range}
s _{Low Shutdown Current: < 100µA}
s _{Switchers Run Out-of-Phase to Minimize CIN}
s _{Small 28-Pin Narrow SSOP Package}
U
APPLICATIO S
s _{Complete Power Supply Controller for Intel}
Mobile Pentium^® Processors
s _{Intel Mobile Pentium Core, I/O, Clock Supplies}
s _{Multiple Logic Supply Generator}
The LTC^®1705 is a complete power supply controller for
Intel Mobile Pentium processors. It includes two switch-
ing regulator controllers, each designed to drive a pair of
N-channel MOSFETs in a voltage mode feedback, syn-
chronous buck configuration, to provide the core and I/O
supplies. The core controller includes a 5-bit DAC that
conforms to the Intel Mobile VID specification. The IC also
includes a low dropout linear regulator (LDO) that delivers
up to 150mA of output current to provide the CLK supply.
The LTC1705 uses a constant-frequency 550kHz PWM
architecture, minimizing external component size and
cost, as well as optimizing load transient performance. It
provides better than 1.25% DC accuracy at its core output,
and 2% at I/0 and CLK outputs. The high performance
feedback loops allow the circuit to keep total output
regulation within ±5% under all transient conditions. An
open-drain PGOOD flag indicates that all three outputs are
within ±10% of their regulated values. A shutdown circuit
disables all three outputs if the RUN/SS pin is pulled to
ground. In this mode, the LTC1705 supply current drops
to below 100µA.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corporation.
TYPICAL APPLICATIO
Intel Mobile Pentium VRM Supply
V_IN
5V
C_IN
330µF
+
1µF
10V
D_CPC
MBR
×3
0520LT1
QTCA QTCB
5
L_C
0.68µH
3
C_CPC
1µF
6
V_OUTC
0.9V TO 2V
15A
1µF ⁺
C_OUTC
180µF
4V
×6
QBCB
QBCA
4
R_IMAXC, 27k ₈
13
11
R31 C11
C31 _{1.8k 1800pF}
1800pF
SHUTDOWN
C_IN: KEMET T510X337K010AS
C_OUTC: PANASONIC EEFUE0G181R
C_OUTIO: AVX TPS0107M010R0065
L_C: SUMIDA CEP125-4712-T007
L_IO: SUMIDA CDRH6D28-3R0
QTCA, QTCB, QBCA, QBCB: FAIRCHILD FDS6670A
QTIO, QBIO: 1/2 FAIRCHILD NDS8926
R21, 11k
10k
C21
330pF
C_SS
0.1µF
10
9
7
12
14–18
5-BIT VID
R_PGOOD
5k
2
22
PV_CC
TGC
BOOSTC
PGOOD
SWC
BGC
I_MAXC
SENSEC
FBC
LTC1705
COMPC
RUN/SS
PGND
GND
VID4:0
10Ω
10µF
19
D_CPIO
MBR
0520LT1
V_CC
26
TGIO
27
BOOSTIO
25
SWIO
C_CPIO
1µF
BGIO
I_MAXIO
COMPIO
FBIO
28
1 ^{RIMAXI0, 16k}
21
R22, 11k
C22
20
100pF
QTIO
L_IO
3µH
QBIO
C_OUTIO
100µF
+
10V
×2
RB2
C12
10k
2200pF ^1%
V_INCLK
V_OUTCLK
24
+
23
C_VINCLK
10µF
10V
+ C_VOUTCLK
10µF
10V
V_INCLK
3.3V
V_OUTCLK
2.5V
150mA
1µF
1µF
R12
8.87k
1%
V_OUTIO
1.5V
3A
1705 TA01
1