QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
1
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-
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
Table 1. Typical DC1208A Performance Summary (T
A
= 25°C)
PARAMETER CONDITION VALUE
Minimum Input Voltage Voltage at VIN 7V
LTC4151 Maximum Operating Input Voltage 80V
Maximum Input Voltage
DC1208 Maximum Operating VIN Voltage (Note 1) 75V
Shutdown JP3 on FLOAT 1mA
LTC4151 Supply Current
Shutdown JP3 on LO 100µA
ADC Resolution 12 Bits
(SENSE+ – SENSE-) 81.92mV
VIN 102.4V
Full Scale Voltage
ADIN 2.048V
Full Scale Current R1 (Sense) = 0.02
Ω
, I = (SENSE+ – SENSE-) / R1
4.096A
(SENSE+ – SENSE-) 20µV
VIN 25mV
LSB Step Size
ADIN 0.5mV
Note 1: DC1208 has a Transient Voltage Suppressor to assist with protection from voltages that can exceed absolute maxi-
mum voltages.
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
2
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.
Select I2C Address by setting JP1 and JP2.
2.
Place jumper JP3 on FLOAT to enable the
LTC4151.
3.
Connect I2C master to SDA and SCL or con-
nect QuickEval demonstration board to J1
through 14-pin ribbon cable and open software.
4.
Connect the input power supply across VIN and
GND.
5.
Apply a load from VOUT to GND.
6.
Apply a voltage at ADIN.
7.
Read and write to the LTC4151 through I2C.
Figure 1. DC1208 Proper Measurement Equipment Setup
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
3
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
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
4
ADCs values are read in the left column. A Snap-
shot button for each ADC can be clicked on to per-
form on-demand measurement of the selected
voltage. Register bits status are read in the regis-
ters section. Configurations can be done by
checking the bits in the CONTROL register ‘G’.
The QuickEval components are optional and used
for evaluation purpose only on the demo board.
These components are not needed in the final ap-
plication and should not be included.
Figure 2. LTC4151 QuickEval Interface
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1208A
LTC4151CDD
HIGH VOLTAGE MONITOR WITH ADC AND I2C
5
OPT
U3
LT3010EMS8E-5
1
2
4
5
8
9
OUT
ADJ
G N D
SHDN
IN
G N D
5V ISO1
PS9817-2
2
1
54
3 6
7
8
ISO2
PS9817-2
2
1
5 4
36
7
8
TP
VOUT
R5
5.1K
JP3
OPT
SDA/SDAI
E9
GND
LO
R6
5.1K
PULLUP
E16
SHDN/SDAO
LTC4151-1 OPTION
HI
FLOA T
QUICK EVAL DEMO ONLY
E5
ADIN
TP4
ISO_SDA
C4
0.1uF
OPT
E8
VP
R9
0
C1
1000pF
100V
LO
VIN
LO
U4
24LC025-I/ST
1
6
3
4
5
2
7
8
A0
SCL
A2
VSS
SDA
A1
WP
V C C
3
ADR0
VS
OPT
SCL
VP
C3
0.01uF
J1
1
3
5
7
9
11
13
2
4
6
8
10
12
14
+
+
+
+
+
+
+
+
+
+
+
+
+
+
OPT
E1
VIN
SHDN
R8D
20K
JP2
ADR1
1
2
3
4
E6
SDA/SDAI
OPT
SHDN/SDAO
JP1
ADR0
1
2
3
4
TP5
ISO_SCL
FLO A T
OPT
OPT
E3
VOUT
C2
0.1uF
TP3
ISO_VP
ISO_I2C
1
E4
GND
R7
5.1K
R4
10K
OPT
ADR1
HI
OPT
R8B
20K
R8C
20K
C6
0.47uF
FLO AT
R13
51
OPT
2
7V - 75V
R12
1K
E2
GND
R10
VS
R8A
20K
R11
1K
R3
10K
TP6
ISO_GND
OPT
OPT
R1 0.02 1/2W
OPT
E7
SCL
SDAO
SDAI
U1
LTC4151CDD
1
2
3
4
6
7
5
8
9
1 1
10
SENSE+
VIN
ADR1
ADR0
SCL
SDA/
ADIN
SHDN/
GND
G N D
SENSE-
D1
SMAT70A
12
