LTC3815_15 Datasheet, PDF (32/42 Pages) Linear Technology – 6A Monolithic Synchronous DC/DC Step-Down Converter with Digital Power System Management

LTC3815
Applications Information
Connecting the USB to the I²C/SMBus/PMBus
Controller to the LTC3815 In System
The LTC USB to I²C/SMBus/PMBus controller can be inter-
faced to the LTC3815 on the user’s board for programming,
telemetry and system debug. The controller, when used
in conjunction with LTpowerPlay™, provides a powerful
way to debug an entire power system.
Figure 14 illustrates the application schematic for power-
ing, programming and communication with one or more
LTC3815s via the LTC I²C/SMBus/PMBus controller
regardless of whether or not system power is present. If
system power is not present, the LTC3815 can be pow-
ered directly from the DC1613's 3.3V supply. Since the
current sourcing ability of this 3.3V supply is limited, the
LTC3815 should be lightly loaded (<10mA) and operating
in discontinuous mode (MODE/SYNC tied to 3.3V).
In addition any device sharing the I²C bus connections
with the LTC3815 should not have body diodes between
the SDA/SCL pins and their respective V_DD node because
this will interfere with bus communication in the absence
of system power.
LTC
CONTROLLER
HEADER
ISOLATED 3.3V
SDA
SCL
2.25V TO 5.5V
10k 10k
TO LTC DC1613
USB TO I²C/SMBus/PMBus
CONTROLLER
* CONNECT MODE PIN TO 3.3V WHEN POWERING
THE LTC3815 FROM THE DC1613 3.3V SUPPLY.
V_IN
MODE
V_IN*
LTC3815
SDA
SCL
WP SGND
V_IN
MODE
V_IN*
LTC3815
SDA
SCL
WP SGND
3815 F12
Figure 14. LTC Controller Connection
3815p
32
For more information www.linear.com/LTC3815