1
dc1733af
DEMO MANUAL DC1733A
DESCRIPTION
LT3669
Industrial Transceiver with Integrated
Step-Down Regulator and LDO
Demonstration circuit 1733A is an industrial transceiver
with integrated step-down regulator and LDO featuring the
. The board operates from 7.5V to 40V when JP7 is
set to L+. When the JP7 is set to RES, the minimum input
voltage is 16.5V. The board withstands transients up to
60V. The step-down regulator output is 5V. The LDO output
is 3.3V. There are two assembly versions. DC1733A-A is
for the LT3669 and DC1733A-B is for the LT3669-2. The
difference is the LT3669 has an integrated catch diode.
The LT3669-2 requires an external catch diode. Table 1
shows the differences between the two versions.
L
, LTC, LTM, LT, Burst Mode are registered trademarks of Linear Technology Corporation.
Other product names may be trademarks of the companies that manufacture the products..
PERFORMANCE SUMMARY
The board also provides various interfaces for line drivers
and receivers. JP8 to JP11 set the signal sources or levels
for TXEN1, TXEN2, TXD1 and TXD2.
The LT3669 data sheet gives complete descriptions of the
part, operation and application information. The data sheet
must be read in conjunction with this quick start guide for
working on or modifying the demo circuit 1733A.
Design files for this circuit board are available.
Call the LTC Factory.
Specifications are at T
A
= 25°C
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
L+
Input Supply
7.5
40
V
V
BUCK
Output Voltage
Step-Down Regulator
4.75
5
5.25
V
V
LDO
Output Voltage
LDO
3.135
3.3
3.465
V
I
BUCK
Maximum Buck Output Current
LT3669, Step-Down Regulator V
BUCK
= 5V
100
mA
LT3669-2, Step-Down Regulator V
BUCK
= 5V
300
mA
I
LDO
Maximum LDO Output Current
LT3669, VLDO = 3.3V
100
mA
LT3669-2, VLDO = 3.3V
150
mA
FSW
Switching Frequency
600
kHz
EFF
Efficiency
LT3669, L+ = 12V, V
BUCK
= 5V, I
BUCK
= 100mA
65
%
LT3669-2, L+ = 12V, V
BUCK
= 5V, I
BUCK
= 300mA
76
%
TRST
Reset Timeout Period
C5=100nF
12.5
ms
Table 1. Version Table
ASSY TYPE
U1
I
LDO
I
BUCK
C8
C9
D6
L1
DC1733A-A
LT3669EUFD
0.1A
0.1A
10µF
0.1µF
OPEN
82µH, CDRH4D22HPNP-820MC
DC1733A-B
LT3669EUFD-2
0.15A
0.3A
22µF
0.22µF
DFLS160
33µH, CDRH50D28RNP-330MC
