DEMO MANUAL DC1738A
LTM8028
36V
IN
, UltraFast, Low Output
Noise, 5A µModule Regulator
Description
Demonstration circuit 1738A features the
LTM
®
8028,
a
µModule
®
step-down converter that integrates both a high
efficiency switching regulator and a 5A UltraFast™ linear
regulator, resulting in a low noise solution suitable for high
speed data applications. The demo circuit is designed for
an input voltage of 6V to 36V and an operating frequency
of 250kHz. The output voltage is digitally programmable
from 0.8V to 1.8V in 50mV increments by adjusting the
three tri-state inputs VO0, VO1, and VO2.
The user may adjust the output voltage over a continuous
±10% range by applying a voltage to MARGA. A PGOOD
signal indicates that the output is within 10% of the target
voltage. The SENSEP pin creates a Kelvin sense connec-
tion to account for voltage drops due to PCB resistances
between the regulator and the load.
The LTM8028 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this demo manual
prior to working on or modifying DC1738A.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks
and UltraFast is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
BoarD photo
dc1738af
1
DEMO MANUAL DC1738A
performance summary
PARAMETER
Input Voltage Range
Output Voltage*
Maximum Output Current
Switching Frequency
*For other output voltage settings, refer to Table 1
R
T
= 165kΩ
Specifications are at T
A
= 25°C
MIN
6
1.773
5
250
1.8
TYP
MAX
36
1.827
UNITS
V
V
A
kHz
CONDITIONS
V
OUT
= 0.8V to 1.8V
Default Setting
Table 1: VO2 to VO0 Setting vs Nominal Output Voltage
V
IN
= 12V
V
OUT
= 1.5V
–20 I
OUT
= 5A
INTENSITY (dBm)
–40
–60
–80
–100
–120
–140
0
0.5
1
1.5
3.5
FREQUENCY (MHz)
2
2.5
3
4
4.5
5
0
VO2
Low
Low
Low
Low
Low
Low
Low
Low
Low
Float
Float
Float
Float
Float
Float
Float
Float
Float
High
High
High
VO1
Low
Low
Low
Float
Float
Float
High
High
High
Low
Low
Low
Float
Float
Float
High
High
High
Don't Care
Don't Care
Don't Care
VO0
Low
Float
High
Low
Float
High
Low
Float
High
Low
Float
High
Low
Float
High
Low
Float
High
Low
Float
High
V
OUT(NOM)
0.80V
0.85V
0.90V
0.95V
1.00V
1.05V
1.10V
1.15V
1.20V
1.25V
1.30V
1.35V
1.40V
1.45V
1.50V
1.55V
1.60V
1.65V
1.70V
1.75V
1.80V
dc1738a F01
Figure 1. DC1738A Output Noise Spectrum
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2
DEMO MANUAL DC1738A
Quick start proceDure
Demonstration circuit 1738A is an easy way to evaluate
the performance of the LTM8028. Refer to Figure 2 for
proper measurement equipment setup and follow the
procedure below:
1. Place JP1-JP3 according to Table 1 to program the
desired output voltage.
2. With power off, connect the input power supply, load
and meters, as shown in Figure 2. Preset the V
IN
supply
between 6V to 36V.
3. Turn on the power at the input.
4. Check for the proper output voltage.
NOTE: If there is no output, temporarily disconnect the load
to make sure that the load is not set too high or is shorted.
5. Once the proper output voltage is established, adjust
the load within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
6. In order to use the Kelvin sense connection to account
for output voltage drops, place JP4 in the SENSEP
position and connect the SENSEP turret at the input
of the load.
7. In order to minimize EMI noise, an input filter can be
utilized by removing R6 on the bottom of the board
and populating the optional circuit components.
Figure 2. Proper Measurement Equipment Setup
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3
DEMO MANUAL DC1738A
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
1
2
3
4
5
6
7
1
2
3
4
5
6
7
QTY
1
1
1
1
1
1
1
1
1
2
1
1
1
0
0
0
1
0
0
0
8
3
1
4
1
4
4
REFERENCE
C1
C2
C4
C8
C9
C10
C12
R1
R3
R4, R7
R6
R9
U1
C3, C6 (OPT)
C5 (OPT)
C7 (OPT)
C11
R2, R5, R8 (OPT)
FB1 (OPT)
L1 (OPT)
E1-E8
JP1-JP3
JP4
J1-J4
J5
XJP1-XJP4
PART DESCRIPTION
CAP., X7R, 10µF, 50V, 10%, 1210
CAP., X7R, 0.01µF, 16V, 5%, 0603
CAP., X5R, 100µF, 6.3V, 20%, 1210
CAP., POSCAP, 470µF, 4V, D3L
CAP., X5R, 10µF, 10V, 20%, 0805
CAP., X5R, 4.7µF, 4V, 20%, 0603
CAP., X5R, 22µF, 10V, 20%, 0805
RES., CHIP, 402kΩ, 1/10W, 1%, 0603
RES., CHIP, 165kΩ, 1/16W, 1%, 0603
RES., CHIP, 100kΩ, 1/16W, 1%, 0603
RES., CHIP, 0Ω, 1/4W, 1%, 1206
RES., CHIP, 49.9Ω, 1/16W, 1%, 0603
IC., MODULE REGULATOR, LTM8028EY, BGA-114 LEAD
CAP., 1210
CAP., 0603
CAP., ALUM
CAP., ALUM, 22µF, 50V
RES., CHIP, 0603
FERRITE BEAD, M TYPE
IND., 10µH
TESTPOINT, TURRET, 0.094"
JMP, 0.079", SINGLE ROW HEADER, 4 PIN
JMP, 0.079", SINGLE ROW HEADER, 3 PIN
CONN, BANANA JACK, KEYSTONE-575-4
CONN, BNC
SHUNT, 0.079" CENTER
TAIYO YUDEN, FBMJ3216HS800T
VISHAY, IHLP-2525CZ-01
MILL-MAX, 2501-2-00-80-00-00-07-0
SAMTEC, TMM-104-02-L-S
SAMTEC, TMM-103-02-L-S
KEYSTONE, 575-4
CONNEX, 112404
SAMTEC, 2SN-BK-G
SUN ELECT., 50CE22BS
MANUFACTURER/PART NUMBER
MURATA, GRM32ER71H106K
AVX, 0603YC103JAT2A
AVX, 12106D107MAT2A
SANYO, 4TPF470ML
TAIYO YUDEN, LMK212ABJ106MG-T
AVX, 06034D475MAT2A
TAIYO YUDEN, LMK212BBJ226MG-T
VISHAY, CRCW0603402KFKEA
VISHAY, CRCW0603165KFKEA
VISHAY, CRCW0603100KFKEA
NIC, NRC12ZOTRF
VISHAY, CRCW060349R9FKEA
LINEAR TECHNOLOGY CORPORATION, LTM8028EY
Required Circuit Components
Additional Demo Board Circuit Components
Hardware: For Demo Board Only
MTGS AT 4 CORNERS STAND-OFF, SNAP-ON, NYLON, 0.50" TALL
dc1738af
4
5
4
3
2
1
VOB
SENSEP
E5
JP4
SENSEP
VOUT
VOB
VOB
VOB
D
D
* REFER TO DEMO MANUAL
1
2
3
4
3
2
1
VO0 *
HIGH
LOW
FLOAT
JP1
1
2
3
4
VO1 *
HIGH
LOW
FLOAT
JP2
1
2
3
4
VO2 *
HIGH
LOW
FLOAT
JP3
VIN
B5
A6
B6
6V - 36V
E6
R6
**
VO0
VO1
VO2
VOB
SENSEP
A9
E8
J3
J5
BNC
R9
49.9
J4
E3
C10
4.7uF
4V
0603
C9
10uF
10V
0805
C12
22uF
10V
0805
C3
OPT.
1210
R1
402K
C1
10uF
50V
1210
A5
VIN
IN
VOUT
0.8V - 1.8V / 5A
J1
+
C11
22uF
50V
0
1206
GND
R2
OPT
J2
H1
H2
J1
J2
K1
K2
L1
L2
VIN
VIN
VIN
VIN
VIN
VIN
VIN
VIN
RUN
SYNC
SS
F1
E2
D2
schematic Diagram
E7
C
SYNC
R4
100K
R3
165K
C2
10nF
R8
OPT
U1
LTM8028EY
+
J9
J10
J11
K9
K10
K11
L9
L10
L11
C4
100uF
6.3V
1210
C8
470uF
4V
D3L
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
A10
A11
B10
B11
C10
C11
D10
D11
E10
E11
F10
F11
GND
C
E1
D1
E1
B7
IMAX
RT
PGOOD
VOB
R7
100K
BKV
BKV
BKV
BKV
BKV
BKV
BKV
BKV
BKV
PGOOD
E2
R5
OPT
MARGA
E4
0V - 1.2V
B
D3
D4
D5
D6
D7
D8
D9
E3
E4
E5
E6
E7
E8
E9
F2
F3
F4
F5
F6
F7
F8
F9
G4
G5
G6
G7
G8
G9
G10
G11
H4
H5
H6
H7
H8
H9
H10
H11
J4
J5
J6
J7
J8
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
A1
A2
A3
A4
B1
B2
B3
B4
B8
B9
C1
C2
C3
C4
C5
C6
C7
C8
C9
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
A8
TEST
A7
MARGA
L8
GND
L7
GND
L6
GND
L5
GND
L4
GND
K8
GND
K7
GND
K6
GND
K5
GND
K4
GND
B
OPTIONAL CIRCUIT
**
**
REMOVE R6 IF OPTIONAL CIRCUIT IS USED.
C7
22uF
50V
VIN
FB1
Bead
L1
IN
10uH
IHLP-2525CZ-01
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
+
4
3
2
C5
0.01uF
50V
C6
10uF
50V
1210
A
A
NOTE: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS AND CAPACITORS ARE 0603
2. INSTALL SHUNTS AS SHOWN.
5
1
DEMO MANUAL DC1738A
dc1738af
Figure 3. DC1738A Demo Circuit Schematic
5
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