LTC4015_15 Datasheet, PDF (19/76 Pages) Linear Technology – Multichemistry Buck Battery Charger Controller with Digital Telemetry System

LTC4015
Operation
VIN_UVCL_SETTING values, applies the new maximum
power point, and resumes dithering at that point. With the
automatic MPPT algorithm enabled, a solar panel can be
used as a suitable power source for charging a battery
and powering a load. The MPPT feature can be enabled
either via the serial port or by connecting the MPPT pin to
the 2P5V_CC pin or a suitable GPIO from a microcontroller.
The MPPT algorithm may not work for all solar panel
applications and does not have to be used, alternatively a
solar panel can be used without the MPPT algorithm by
setting the UVCL V_IN minimum value to match the optimum
loaded solar panel voltage by selecting the appropriate
VIN_UVCL_SETTING and UVCLFB pin resistor divider.
Serial Port, SMBus and I²C Protocol Compatibility
The LTC4015 uses an SMBus/I²C style 2-wire serial port
for programming and monitoring functions. Using the
serial port, the user may program alerts, set control pa-
rameters and read status data. The timing diagram shows
the relationship of the signals on the bus. The two bus
lines, SDA and SCL, must be HIGH when the bus is not in
use. External pull-up resistors or active loads, such as the
LTC1694 SMBus accelerator, are required on these lines.
The LTC4015 is both a slave receiver and slave transmitter.
It is never a master. The control signals, SDA and SCL, are
scaled internally to the DV_CC supply in compliance with
the I²C specification. DV_CC must be connected to the same
power supply as the bus pull-up resistors.
Aside from electrical levels and bus speed, the SMBus
specification is generally compatible with the I²C bus
specification, but extends beyond I²C to define and stan-
dardize specific protocol formats for various types of
transactions. The LTC4015 serial port is compatible with
the 400kHz speed and ratiometric input thresholds of the
I²C specification and supports the read word and write
word protocols of the SMBus specification. It has built-in
timing delays to ensure correct operation when addressed
from an I²C compliant master device. It also contains input
filters designed to suppress glitches.
tery charger states or status events occur. This offloads
much of the continuous monitoring from the system’s
microcontroller and onto the LTC4015; reducing bus traffic
and microprocessor load.
The SMBALERT pin is asserted (pulled low) whenever an
enabled alert occurs (see the following tables and register
descriptions). The LTC4015 will de-assert (release) the
SMBALERT pin only after successfully responding to an
SMB alert response address (ARA). The alert response is
an SMB protocol used to respond to an SMBALERT. The
host reads from the alert response address 0001_1001b
(0x19) and each part asserting SMBALERT begins to
respond with its address. The responding parts arbitrate
in such a way that only the part with the lowest address
responds. Only when a part has responded with its address
does it release the SMBALERT signal. If multiple parts
are asserting the SMBALERT signal then multiple reads
from the ARA are needed. Therefore, only a response of
1101_0001b (0xD1) will clear the LTC4015/SMBALERT
signal. Any other response indicates a device with a lower
I²C address also requests attention from the host. For more
information refer to the SMBus specification.
Table 1. Shows a Summary of LTC4015 Limit Alerts. Each Alert
Has an Associated Enable (Mask), Limit, and Bit That Is Set to 1
to Indicate the Enabled Alert Has Occurred.
LIMIT ALERTS
ALERT ALERT
ENABLE LIMIT SET
BITS POINT
(0x0D) REGISTER
ALERT
REPORTING
BITS (0x36)
Measurement System Valid Alert
15
N/A
15
(ADC Ready)
Reserved
14
N/A
N/A
Coulomb Counter Accumulator Low 13, 12 0x10, 0x11 13, 12
and High Alert
Battery Voltage Low and High Alert 11, 10 0x01, 0x02 11, 10
Input Voltage Low and High Alert
9, 8 0x03, 0x04 9, 8
System Voltage Low and High Alert 7, 6 0x05, 0x06 7, 6
Input Current High Alert
5
0x07
5
Battery Current Low Alert
4
0x08
4
Die Temperature High Alert
3
0x09
3
Programmable Alerts and Interrupt Controller
Battery Series Resistance High Alert 2
0x0A
2
NTC Ratio High and Low Alert
1, 0 0x0B, 0x0C 1, 0
The serial port supports the SMBus SMBALERT proto-
col. An alert can optionally be generated if a monitored
parameter exceeds a programmed limit or if selected bat-
4015f
For more information www.linear.com/LTC4015
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