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DC059A-B

P1-P3P4-P6P7-P8
1
DEMO MANUAL DC059
LTC1174 High Efficiency
Step-Down DC/DC Converter
UW
AT
Y
P
I
CA
LPER
F
O
R
C
E
CCHARA TERIST
IC
U
AD
BOARD PH TOO
S
S
D
U
ESCRIPTIO
Board A Efficiency
Board B Efficiency
V
IN
= 9V
V
OUT
= 5V
LOAD CURRENT (mA)
65
75
85
95
90
80
70
EFFICIENCY (%)
500
DC059 • G01
1 10 100
I
PGM
= V
IN
I
PGM
= 0V
V
IN
= 9V
V
OUT
= 3.3V
LOAD CURRENT (mA)
60
70
80
90
85
75
65
EFFICIENCY (%)
500
DC059 • G02
1 10 100
I
PGM
= V
IN
I
PGM
= 0V
DEMO MANUAL DC059
NO DESIGN SWITCHER
This demonstration circuit is a step-down (buck) regulator
using the high voltage LTC
®
1174. Exclusive use of
surface mount components results in a highly efficient
application in a small board space. This demo board
highlights the simplicity of the LTC1174 in stepping down
input voltages ranging between 4V to 16.5V. The LTC1174
is a current mode DC/DC converter, thus the peak inductor
current is well-defined and provides excellent transient
response. To optimize efficiency, the LTC1174 automati-
cally switches between continuous and Burst Mode
TM
operation. To further optimize the LTC1174 for a wide
range of applications, the maximum inductor current is
pin selectable to either 340mA or 600mA. The part can also
be shut down, drawing a mere 1µA, making this part ideal
for current sensitive applications. An onboard low battery
detector allows the user to monitor the input supply
through an external resistive divider. This divided voltage
is compared with an internal 1.25V reference voltage.
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.
SYMBOL PARAMETER CONDITIONS BOARD SUFFIX VALUE
V
IN
Input Voltage Range ALL 4V to 16.5V
V
OUT
Output Voltage LTC1174HV-5 A 5.0V ± 0.15V
LTC1174HV-3.3 B 3.3V ± 0.10V
LTC1174HV, R1=54.9K, R2=33.3K C 3.3V ± 0.10V
I
OUT
Maximum Output Current I
PGM
= V
IN,
V
OUT
= 5.0V A 380mA
I
PGM
= 0V, V
OUT
= 5.0V A 125mA
I
PGM
= V
IN,
V
OUT
= 3.3V B 400mA
I
PGM
= 0V, V
OUT
= 3.3V B 130mA
I
PGM
= V
IN,
V
OUT
= 3.3V C 375mA
I
PGM
= 0V, V
OUT
= 3.3V C 130mA
V
RIPPLE
Typical Output Ripple A & B 80mVp-p
C 40mVp-p
PERFORWAUCE SUWWARY
WWWU
Component Side
2
DEMO MANUAL DC059
PACKAGE A D S
W
A
W
CH
E
TI
ICDAGRA
U
S
SYMBOL PARAMETER CONDITIONS BOARD SUFFIX VALUE
DV
OUT
Typical Line Regulation 6V < V
IN
< 16.5V, I
LOAD
= 350mA, I
PGM
= V
IN
ALL 25mV
6V < V
IN
< 16.5V, I
LOAD
= 125mA, I
PGM
= 0V ALL 7mV
Typical Load Regulation 20mA < I
LOAD
< 350mA, I
PGM
= V
IN,
V
IN
= 9V ALL 10mV
20mA < I
LOAD
< 125mA. I
PGM
= 0V, V
IN
= 9V ALL 8mV
V
LBTRIP
Low-Battery Trip Point ALL 1.25V
V
IH
SHUTDOWN Pin High Minimum Voltage at Pin 8 for Device to Be Active ALL 1.2V
V
IL
SHUTDOWN Pin Low Maximum Voltage at Pin 8 for Device to Be in Shutdown ALL 0.75V
I
Q
Typical Input DC Active Mode, 4V < V
IN
< 16.5 V, I
PGM
= 0V ALL 450µA
Supply Current Sleep Mode, 4V < V
IN
< 16.5V ALL 130µA
V
SHUTDOWN
= 0, 4V < V
IN
< 16.5V ALL 1µA
PERFORMANCE SUMMARY
1
2
3
4
8
7
6
5
TOP VIEW
*ADJUSTABLE OUTPUT VERSION
SHUTDOWN
I
PGM
V
IN
SW
V
OUT/
(V
FB
*)
LB
OUT
LB
IN
GND
S8 PACKAGE
8-LEAD PLASTIC SO
LTC1174HVCS8-5
LTC1174HVCS8-3.3
LTC1174HVCS8
7
4
+
+
V
IN
LB
IN
3
U1
6
2
LB
IN
SHDN
V
OUT 
(V
FB
)
8
1
SW
5
SHDN
C3
0.1µF
C2
22µF
50V
LB
OUT
LB
OUT
I
PGM
GND
GND
LTC1174HV
LTC1174HV-5
LTC1174HV-3.3
I
PGM
D1
MBR0520LT1
L1
68µH
JUMPER, J1, IS PRESENT
FOR BOARD A AND B
THIS NETWORK IS PRESENT
FOR BOARD C ONLY
C1
100µF
10V
J1
R1
54.9K
C4
6800pF
V
OUT
DC059•F01
R2
33.2K
BOLD LINES INDICATE HIGH CURRENT PATH
Figure 1. High Efficiency Step-Down DC/DC Converter
REFERENCE
DESIGNATOR QUANTITY PART NUMBER DESCRIPTION VENDOR TELEPHONE
C1 1 TPSD107K010 Cap, Tant, 100µF, 10V, 20% AVX (803) 448-9411
C2 1 TPSD226K025 Cap, Tant, 22µF, 25V, 10% AVX
C3 1 12065C104KAT Cap, Mono Chip, 0.1µF, 50V, 10% AVX
C4 1 VJ1206Y682KXBT Cap, CER Chip, 6800pF, 100V Vitramon (203) 268-6261
D1 1 MBR0520LT1 Schottky Diode Motorola (602) 244-3558
L1 1 CDRH74-680 Inductor, 68µH Sumida (708) 956-0666
R1 1 CR325492FT 54.9kΩ, 1% AVX (803) 448-9411
R2 1 BCR1/83322FT 33.2kΩ, 1% Beckman Industrial (714) 447-2345
J1 1 CJ32-000-T 0Ω, Jumper AVX
U1 1 LTC1174HVCS8-5 IC, LTC1174HV-5 Board A LTC (408) 432-1900
LTC1174HVCS8-3.3 IC. LTC1174HV-3.3 Board B
LTC1174HVCS8 IC, LTC1174HV Board C
PARTS LIST
3
DEMO MANUAL DC059
QUICK START GUIDE
This demonstration board is simple to use. Just follow
the steps outlined below and you are ready to start your
evaluation of the LTC1174.
• Connect your power supply between the V
IN
terminal
and GND terminal.
• Connect the SHDN pin to a voltage greater than 1.2V
for the part to be active. This pin can also be shorted
to V
IN
pin. DO NOT FLOAT THIS PIN AS THIS MAY
RESULT IN INTERMITTENT OPERATION OF THE
PART.
• Connect the I
PGM
pin either to GND or V
IN
depending
upon the amount of current you want to source from
the part. Again, DO NOT FLOAT THIS PIN.
• The LB
OUT
pin is a current sinking pin. When the LB
IN
pin goes below 1.25V, the LB
OUT
pin will sink 1mA
of current.
• The LB
IN
pin is the low battery detector input pin.
Normally, its input comes from the input voltage
through a resistor divider network (see Low Battery
Detector section).
The circuit shown in Figure 1 operates between input
voltages of 4V and 16.5V. For the regular fixed 3.3V or
5V version, the external components are the same except
for U1. For the low noise demonstration circuit, it
requires an adjustable version for U1 and an additional
passive network.
This demonstration unit is intended for the evaluation of
the LTC1174 switching regulator IC and was not designed
for any other purpose.
OPERATION
The LTC1174 uses a constant off-time architecture to
switch its internal P-channel power MOSFET. The off-time
is set by an internal timing capacitor and the operating
frequency is a function of V
IN
.
The output voltage is set by an internal resistive divider.
A voltage comparator (A1) compares the divided output
voltage to a reference voltage of 1.25V.
U
OPERATIO
–
+
–
+
–
+
–
+
–
+
A2
A1
1.25V
REFERENCE
A3
SW
A5
A4
V
LIM1
V
LIM2
V
IN
C
TIME
gm
V
FB
SLEEP
SHUTDOWN
*R1 = 93.5k FOR LTC1174-5 AND R1 = 51k FOR LTC1174-3.3
LB
IN
RESET
V
TH2
V
TH1
R
SENSE
0.1Ω
R1*
31.5k
V
OUT
DC059 • F02
LB
OUT
GND
4
I
PGM
SET
Q
V
FB
1
5
8
3
6
7
2
Figure 2. LTC1174 Block Diagram
P1-P3P4-P6P7-P8

DC059A-B

Mfr. #:
Buy DC059A-B
Manufacturer:
Analog Devices Inc.
Description:
Power Management IC Development Tools LTC1174HV-3.3 - HIGH EFFICIENCY STEP-DOW
Lifecycle:
New from this manufacturer.
Delivery:
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