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DC247A

P1-P3P4-P6P7-P8
1
DEMO MANUAL DC247
DESIGN-READY SWITCHER
LTC1735 Constant
Frequency Synchronous DC/DC Converter
Demonstration Circuit DC247 demonstrates a 1.6V/9A
notebook CPU application using the LTC
®
1735 switching
regulator controller. A high performance, constant fre-
quency, current mode architecture generates a precise
low voltage CPU core supply. Protection features include
an externally defeatable overcurrent latchoff and internal
current foldback for overload conditions. A soft-latched
crowbar monitors the output voltage for overvoltage pro-
tection. The circuit was designed for a 5V to 26V input
range but allows a 4.5V to 28V range (limited by the
external MOSFETs). Strong output drivers easily handle
large power MOSFETs efficiently. Other output voltages,
to as low as 0.8V, can be configured by modifying the
external resistive divider. External frequency synchroniza-
tion is provided, as are three modes of operation: Burst
Mode
TM
operation to reduce switching losses and maintain
high operating efficiencies, burst inhibit/forced continu-
ous mode and a pulse-skipping mode that provides con-
stant frequency operation down to 1% maximum load
currents with low quiescent current. This results in a
power supply that has very high efficiency, low ripple and
fast transient response. Gerber files for this circuit board
are available. Call the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
LOAD CURRENT (A)
0.01 0.1 1 10
EFFICIENCY (%)
247 TA01
100
90
80
70
60
50
40
V
IN
= 5V
EXTV
CC
= 5V
V
IN
= 24V
V
IN
= 15V
Efficiency
PARAMETER CONDITIONS VALUE
Input Voltage Range (Maximum Input Voltage Limited by External MOSFET and Input Capacitor) 4.5V to 26V
Output Output Voltage 1.6V
Max Output Current (Continuous, Thermally Limited) 9A
Max Output Current (Peak) 10.5A
Typical Output Ripple at 10MHz Bandwidth (Burst Mode Operation) I
O
= 100mA 50mV
P-P
Typical Output Ripple at 10MHz Bandwidth (Continuous) I
O
= 5A 25mV
P-P
Operating Temperature Range 0°C to 50°C
Demo Circuit 247A
DESCRIPTIO
U
PERFOR A CE SU ARY
UW
WW
TYPICAL PERFOR A CE CHARACTERISTICS A D BOARD PHOTO
UUW
2
DEMO MANUAL DC247
DESIGN-READY SWITCHER
PARAMETER CONDITIONS VALUE
V
IN
Line Regulation 4.5V to 26V 0.002%/V
I
OUT
Load Regulation No Load to Full Rated Output –0.03%
I
Q
Supply Current (Typical) with No Load at 15V Input, FCB = INTV
CC
500µA
Supply Current in Shutdown (Typical), V
IN
=15V, JP2 Open 15µA
I
EXTVCC
EXTV
CC
Pin Current, V
EXTVCC
= 5V, V
IN
= 10V, No Load, FCB = INTV
CC
460µA
V
RUN
Run Pin Threshold (Typical) 1.3V
Frequency Operating Frequency (Typical), C
OSC
= 47pF 270kHz
W
ARY
A
U
CE SUPERFOR
WW
Operating Temperature Range 0°C to 50°C
PACKAGE A D SCHE ATIC DIAGRA S
WUW
Figure 1. Demo Board Schematic
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
C
OSC
RUN/SS
I
TH
FCB
SGND
V
OSENSE
SENSE
–
SENSE
+
TG
BOOST
SW
V
IN
INTV
CC
BG
PGND
EXTV
CC
LTC1735
U1
C
SS1
0.1µF
C
B1
0.22µF
C
C1
100pF
C1
47pF
C
C2
330pF
R
C1
33k
R5, 10Ω
R2, 10Ω
R
CS1
0.005Ω
RF1
4.7Ω
R8
0Ω
V
OUT
1.6V/9A
E7
V
OSNS
E11
GND
E8
C
S1
1000pF
CF1
0.1µF
C3
47pF
C
OSC1
47pF
FCB/SYNC
E4
JP1
BURST MODE
JP2
LATCHOFF
RUN
E3
+V
IN
E10
INTV
CC
OFF
ON
+
C2
4.7µF
+
CO3
820µF
4V
+
CO2
100µF
2V
M2
FDS6680A
M1
FDS6680A
247 F01
+
C
IN3
22µF
30V
D1
CMDSH-3
R
S1
10Ω
R7
10k
1%
D2
MBRS340T3
C
IN1
22µF
30V
L1
2µH
EXTV
CC
E2
R3
10k
1%
R1*
10k
V
SEL
E1
Q1*
VN2222
R4*
47k
GND
E9
R6
680k
+
*NOT INSTALLED
C4
1µF
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
C
OSC
RUN/SS
I
TH
FCB
SGND
V
OSENSE
SENSE
–
SENSE
+
TG
BOOST
SW
V
IN
INTV
CC
BG
PGND
EXTV
CC
LTC1735CS16
PARTS LIST
REFERENCE
DESIGNATOR QUANTITY PART NUMBER DESCRIPTION VENDOR TELEPHONE
C1, C3 2 08055A470JAT1A 47pF 50V 5% NPO Capacitor AVX (843) 946-0362
C2 1 TACC475M010R 4.7µF 10V 20% Tantalum Capacitor AVX (207) 282-5111
C4 1 0805ZC105MAT1A 1µF 10V 20% X7R Capacitor AVX (843) 946-0362
C
C1
1 08055A101MAT1A 100pF 50V 5% NPO Capacitor AVX (843) 946-0362
C
C2
1 08055A331MAT1A 330pF 50V 5% NPO Capacitor AVX (843) 946-0362
CB1 1 08055A224KAT1A 0.22µF 50V 20% X7R Capacitor AVX (843) 946-0362
3
DEMO MANUAL DC247
DESIGN-READY SWITCHER
PARTS LIST
CF1, C
SS1
2 08055A104KAT1A 0.1µF 50V 20% X7R Capacitor AVX (843) 946-0362
C
IN1
, C
IN2
2 30SC22M 22µF 30V OS-CON Capacitor SANYO (619) 661-6835
C
IN3
, C
IN4
ALTERNATE THCR70E1H2262T 22µF 50V 20% Y5U Capacitor Marcon (847) 696-2000
CO1, CO2, CO4 ALTERNATE TS10X4470JAT1A 470µF 6.3V Low ESR Capacitor Kemet (408) 986-0424
CO1, C02, C04 ALTERNATE EEFUE0G181R 180µF 4V SP Capacitor Panasonic (201) 348-7522
CO3 1 4SP820M 820µF 4V OS-CON Capacitor SANYO (619) 661-6835
CO2 1 EEFCD0D101R 100µF 2V SP Capacitor Panasonic (201) 348-7522
C
OSC1
1 08055A470JAT1A 47pF 50V 5% NPO Capacitor AVX (843) 946-0362
C
S1
1 08055A102MAT1A 1000pF 50V 5% NPO Capacitor AVX (843) 946-0362
C4 1 0805ZC105MAT1A 1µF 10V 20% X7R Capacitor AVX (843) 946-0362
D1 1 CMDSH-3 0.1A BVR = 30V Schottky Diode Central (516) 435-1110
D2 1 MBRS340T3 3A BVR = 40V Schottky Diode Motorola (800) 441-2447
E2, E3, E4, E7–E10 7 1502-2 Turret Terminal Keystone (718) 956-8900
JP1 1 2802S-03-G2 2mm Pin Header Comm Con (626) 301-4200
JP2 1 2802S-02-G2 2mm Pin Header Comm Con (626) 301-4200
L1 1 ETQP6F2ROHFA 2µH Inductor Panasonic (201) 348-7522
M1, M2 2 FDS6680A 0.013Ω 30V N-Channel MOSFET Fairchild (408) 822-2126
Q1 OPTIONAL VN2222 10Ω 20V N-Channel MOSFET
R1 OPTIONAL CR16-103JM 10k 1/10W 5% Chip Resistor TAD (800) 508-1521
R2, R5, R
S1
3 CR16-100FM 10Ω 1/10W 1% Chip Resistor TAD (800) 508-1521
R3, R7 2 W0805-03-1002B 10k 1/10W 0.1% Chip Resistor IRC (361) 992-7900
R4 OPTIONAL USER DEF 1/10W 1% Chip Resistor
R6 1 CR16-684JM 680k 1/10W 5% Chip Resistor TAD (800) 508-1521
R8 1 CR16-000M 0Ω 1/10W Chip Resistor TAD (800) 508-1521
R
C1
1 CR16-333FM 33k 1/10W 5% Chip Resistor TAD (800) 508-1521
R
CS1
1 LRF2010-01-R005J 0.005Ω 1W 5% Resistor IRC (512) 992-7900
RF1 1 CR16-470JM 4.7Ω 1/10W 5% Chip Resistor TAD (800) 508-1521
U1 1 LTC1735CS16 IC, Switching Regulator Controller LTC (408) 432-1900
2 CCIJ2mm-138-G Jumper Comm Con (626) 301-4200
REFERENCE
DESIGNATOR QUANTITY PART NUMBER DESCRIPTION VENDOR TELEPHONE
QUICK START GUIDE
This demonstration board is easily set up to evaluate the
performance of the LTC1735. Please follow the proce-
dure outlined below for proper operation. Soldered wire
connections are required to properly ascertain the per-
formance of this switching regulator.
• Refer to Figure 2 for proper connection of monitoring
and measurement equipment.
• Connect the input power supply to the V
IN
and GND
terminals on the right hand side of the board with
soldered connections. Do not increase V
IN
over 28V or
the MOSFET(s) WILL BE DAMAGED.
• Connect the load between the V
OUT
and GND terminals
on the right side of the board with soldered connec-
tions.
• The RUN pin can be left unconnected. To shut down
the LTC1735, tie this pin to ground.
• If an external 5V supply is used, connect it to EXTV
CC
.
P1-P3P4-P6P7-P8

DC247A

Mfr. #:
Buy DC247A
Manufacturer:
Analog Devices Inc.
Description:
Power Management IC Development Tools LTC1735CS - CPU Low Voltage High Current
Lifecycle:
New from this manufacturer.
Delivery:
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