QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
LTC4151CDD
DESCRIPTION
Demonstration circuit 1208A features the
LTC4151 high side power monitor that accepts
input voltages from 7V to 80V. In default opera-
tion mode, the onboard 12-bit ADC continuously
measures high side current, input voltage and an
external voltage. Data is reported through the I2C
interface when polled by a host. The monitors can
also perform on-demand measurement in a snap-
shot mode. The LTC4151 features a dedicated
shutdown pin to reduce power consumption.
DC1208A has jumpers on ADR1 and ADR0 to se-
lect one of nine distinct I2C addresses. A shut-
Table 1.
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
CONDITION
Voltage at VIN
LTC4151 Maximum Operating Input Voltage
DC1208 Maximum Operating VIN Voltage (Note 1)
LTC4151 Supply Current
ADC Resolution
(SENSE+ – SENSE-)
Full Scale Voltage
VIN
ADIN
Full Scale Current
R1 (Sense) = 0.02Ω, I = (SENSE+ – SENSE-) / R1
(SENSE+ – SENSE-)
LSB Step Size
VIN
ADIN
Shutdown JP3 on FLOAT
Shutdown JP3 on LO
down jumper enables the LTC4151 or disables it
into a low current shutdown state. I2C communi-
cation can be performed through the QuickEval
system for evaluation of the part.
DC1208A can also be used in an assembly option
with the LTC4151-1 which features split I2C data
pins with data in and an inverted output to drive
opto-isolators.
Design files for this circuit board are available.
Call the LTC factory.
PowerPath is a trademark of Linear Technology Corporation
Typical DC1208A Performance Summary (T
A
= 25°C)
VALUE
7V
80V
75V
1mA
100µA
12 Bits
81.92mV
102.4V
2.048V
4.096A
20µV
25mV
0.5mV
Note 1: DC1208 has a Transient Voltage Suppressor to assist with protection from voltages that can exceed absolute maxi-
mum voltages.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
QUICK START PROCEDURE
Demonstration circuit 1208A is easy to set up to
evaluate the performance of the LTC4151. Refer
to Figure 1 for proper measurement equipment
setup and follow the procedure below:
1.
2.
3.
Connect I2C master to SDA and SCL or con-
nect QuickEval demonstration board to J1
through 14-pin ribbon cable and open software.
Connect the input power supply across VIN and
GND.
Apply a load from VOUT to GND.
Apply a voltage at ADIN.
Read and write to the LTC4151 through I2C.
4.
5.
6.
7.
Select I2C Address by setting JP1 and JP2.
Place jumper JP3 on FLOAT to enable the
LTC4151.
Figure 1. DC1208 Proper Measurement Equipment Setup
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
ADDITIONAL INFORMATION
ADDRESS
Nine distinct I2C bus addresses for the LTC4151/
LTC4151-1 are configurable using the three-state
pins ADR0 and ADR1. These are set on the
DC1208A through JP1 and JP2. Refer to the ad-
dress table shown in the LTC4151 data sheet.
Address bits a6, a5, and a4 are configured to
(110). In addition, the LTC4151/LTC4151-1 will
respond to a mass write address (1100 110)b for
writing to all LTC4151/ LTC4151-1s, regardless of
their individual address settings.
PROTECTION COMPONENTS
Components D1, C1 and R13 on the DC1208A
are optional protection devices. These compo-
nents protect the LTC4151 from an overvoltage
during any ringing due to input turn on, inadvertent
hot plug, or sudden extreme change in output
load. When operating close to the maximum input
voltage, the ringing without these components can
exceed the absolute maximum voltage at the
LTC4151 pins.
D1 provides a clamp selected with a maximum
breakdown voltage below the absolute maximum
rating of the LTC4151 VIN pin. The LTC4151 can
operate up to 80V at VIN, but the zener diode lim-
its the VIN supply voltage on the DC1208 to 75V.
This helps protect against voltage spikes over
80V.
The RC provides a snubber circuit to assist in
dampening and filtering any ringing that can occur.
The RC values can be adjusted according to the
application.
These protection components are optional in the
end application if the input voltage is well below
the absolute maximum and peak voltage due to
spikes or ringing will not damage the LTC4151 or
any other components connected to VIN.
OPTO-ISOLATION (LTC4151-1 OPTION)
The DC1208 has parts placement pads for an
opto-isolated I2C assembly option. The LTC4151-
1 replaces the LTC4151 to provide separated
/SDAO and SDAI pins that simplifies the opto-
isolation.
The LT3010 LDO powers on the
LTC4151 side the high speed opto-couplers over
the full input voltage range. Four 20k resistors in
parallel on /SDAO distribute the power across this
pull-up, enough for up to 80V at VIN.
On the isolated I2C side, the bus supply voltage is
connected across ISO_VP and ISO_GND. Iso-
lated I2C lines connected to ISO_SDA and
ISO_SCL.
I2C BUS PULL-UP
The LTC4151 I2C pull-up resistors on SDA and
SCL are typically pulled up to the microcontroller
supply. The SDA and SCl pins also have an inter-
nal 6V clamp that allow for I2C bus pull resistors
to VIN. When selecting resistor values in the end
application, take in to consideration maximum in-
put voltage, resistor power rating, and resistor
value to provide sufficient bus pull-up to meet I2C
specification requirements. The same considera-
tions apply to /SDAO with the LTC4151-1 option.
QUICKEVAL
The QuickEval system provides a quick and easy
I2C communication from a PC by connecting to
the DC590B controller board though USB and to
the DC1208A through a 14-pin ribbon cable.
When the QuickEval software is opened and the
demo board is connected, the software will identify
the board and bring up the corresponding Graphi-
cal User Interface (GUI). When the demo board is
disconnected the GUI is closed.
On the LTC4151 GUI, click on Auto Find to first
find the LTC4151 address. Click on START to be-
gin polling the LTC4151. SENSE, VIN, and ADIN
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