LTC4151
High Voltage I2C Current
and Voltage Monitor
Features
Description
Wide Operating Voltage Range: 7V to 80V
12-Bit Resolution for Both Current and Voltages
I2C Interface
Additional ADC Input Monitors an External Voltage
Continuous Scan and Snapshot Modes
Shutdown Mode (LTC4151) Reduces Quiescent
Current to 120µA
n Split SDA for Opto-Isolation (LTC4151-1/LTC4151-2)
n Available in 10-Lead MSOP, 10-Lead 3mm × 3mm
DFN and 16-Lead SO Packages
The LTC®4151 is a high side power monitor that operates
over a wide voltage range of 7V to 80V. In default operation
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 LTC4151 can also perform on-demand
measurement in a snapshot mode. The LTC4151 features
a dedicated shutdown pin to reduce power consumption.
The LTC4151‑1/LTC4151-2 feature split I2C data pins to
drive opto-isolators. The data out on the LTC4151-1 is
inverted while that on the LTC4151-2 is not.
n
n
n
n
n
n
Applications
–48V Telecom Infrastructure
n Automotive
n Industrial
n Consumer
n
PART
PACKAGE
FEATURED PIN
LTC4151
DD10, MS10
SHDN
LTC4151-1
DD10, MS10
SDAO
LTC4151-2
S16
SDAO
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Typical Application
12-Bit ADC DNL and INL
1.0
High Side Power Sensing with Onboard ADC and I2C
3.3V
0.02Ω
VIN
7V TO 80V
VIN
2k
ADR1
VDD
2k
–1.0
µCONTROLLER
SHDN
LTC4151
SCL
SCL
SDA
SDA
1024
2048
3072
4096
4151 TA01b
1.0
4151 TA01
0.5
ADC INL (LSB)
ADIN
GND
MEASURED
VOLTAGE
0
CODE
GND
ADR0
0
–0.5
VOUT
SENSE+ SENSE–
ADC DNL (LSB)
0.5
0
–0.5
–1.0
0
1024
2048
CODE
3072
4096
4151 TA01c
4151ff
For more information www.linear.com/LTC4151
1
LTC4151
Absolute Maximum Ratings
(Notes 1, 3)
VIN Voltage.................................................. –0.3V to 90V
SENSE+, SENSE – Voltages............................VIN – 10V or
–0.3V to VIN + 0.3V
ADR1, ADR0 Voltages ............................... –0.3V to 90V
ADIN, SHDN, SDAO, SDAO Voltages............ –0.3V to 6V
SCL, SDA, SDAI Voltages (Note 2)............ –0.3V to 5.5V
SCL, SDA, SDAI Clamp Current................................ 5mA
Operating Temperature Range
LTC4151C/LTC4151C-1/LTC4151C-2.......... 0°C to 70°C
LTC4151I/LTC4151I-1/LTC4151I-2..........–40°C to 85°C
LTC4151H............................................ –40°C to 125°C
Storage Temperature Range
MSOP, SO........................................... –65°C to 150°C
DFN..................................................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec)
MSOP, SO.......................................................... 300°C
Pin Configuration
LTC4151
LTC4151
TOP VIEW
SENSE+
1
10 SENSE–
VIN
2
9 GND
ADR1
3
ADR0
4
7 SDA
ADIN
5
6 SCL
11
TOP VIEW
SENSE+
VIN
ADR1
ADR0
ADIN
8 SHDN
10
9
8
7
6
1
2
3
4
5
SENSE–
GND
SHDN
SDA
SCL
MS PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 150°C, θJA = 85°C/W
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 150°C, θJA = 45°C/W
EXPOSED PAD (PIN 11) PCB GND CONNECTION OPTIONAL
LTC4151-1
LTC4151-1
TOP VIEW
SENSE+
TOP VIEW
10 SENSE–
1
SENSE+
VIN
ADR1
ADR0
ADIN
9 GND
VIN
2
ADR1
3
ADR0
4
7 SDAI
ADIN
5
6 SCL
11
8 SDAO
1
2
3
4
5
10
9
8
7
6
SENSE–
GND
SDAO
SDAI
SCL
MS PACKAGE
10-LEAD PLASTIC MSOP
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 85°C/W
TJMAX = 125°C, θJA = 45°C/W
EXPOSED PAD (PIN 11) PCB GND CONNECTION OPTIONAL
LTC4151-2
TOP VIEW
SENSE+
1
16 SENSE–
VIN 2
15 NC
NC 3
14 NC
NC 4
13 GND
ADR1 5
NC 6
ADR0 7
NC 8
12 SDAO
11 SDAI
10 SCL
9
ADIN
S PACKAGE
16-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 100°C/W
4151ff
2
For more information www.linear.com/LTC4151
LTC4151
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC4151CDD#PBF
LTC4151CDD#TRPBF
LCWZ
10-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC4151IDD#PBF
LTC4151IDD#TRPBF
LCWZ
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC4151HDD#PBF
LTC4151HDD#TRPBF
LCWZ
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC4151CDD-1#PBF
LTC4151CDD-1#TRPBF
LCXC
10-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC4151IDD-1#PBF
LTC4151IDD-1#TRPBF
LCXC
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC4151CMS#PBF
LTC4151CMS#TRPBF
LTCWY
10-Lead Plastic MSOP
0°C to 70°C
LTC4151IMS#PBF
LTC4151IMS#TRPBF
LTCWY
10-Lead Plastic MSOP
–40°C to 85°C
LTC4151HMS#PBF
LTC4151HMS#TRPBF
LTCWY
10-Lead Plastic MSOP
–40°C to 125°C
LTC4151CMS-1#PBF
LTC4151CMS-1#TRPBF
LTCXB
10-Lead Plastic MSOP
0°C to 70°C
LTC4151IMS-1#PBF
LTC4151IMS-1#TRPBF
LTCXB
10-Lead Plastic MSOP
–40°C to 85°C
LTC4151CS-2#PBF
LTC4151CS-2#TRPBF
LTC4151S-2
16-Lead Plastic SO
0°C to 70°C
LTC4151IS-2#PBF
LTC4151IS-2#TRPBF
LTC4151S-2
16-Lead Plastic SO
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN is from 7V to 80V, unless noted. (Note 3)
SYMBOL
General
VIN
IIN
PARAMETER
ISENSE +
ISENSE –
VSHDN(TH)
ISHDN
ADC
RES
VFS
SENSE+ Input Current
SENSE – Input Current
SHDN Input Threshold
SHDN Input Current
LSB
LSB Step Size
TUE
Total Unadjusted Error
VOS
Offset Error
Supply Voltage
Supply Current
Resolution (No Missing Codes)
Full-Scale Voltage
CONDITIONS
MIN
l
VIN = 48V, Normal Operation Mode
VIN = 12V, Shutdown Mode
VIN, SENSE+, SENSE – = 48V
VIN, SENSE+, SENSE – = 48V
MAX
UNITS
1.2
120
5
0.1
1.5
–5
80
1.7
300
9
1
2
–8
V
mA
µA
µA
µA
V
µA
±1.25
±1
±0.75
±1
±5
±6
±8
Bits
mV
V
V
µV
mV
mV
%
%
%
%
LSB
LSB
LSB
7
l
l
l
l
SHDN = 0V
l
1
–3
(Note 4)
(SENSE+ – SENSE – )
VIN
ADIN
(SENSE+ – SENSE – )
VIN
ADIN
(SENSE+ – SENSE – )
VIN (Note 5)
ADIN, C-Grade
ADIN, I-, H-Grade
(SENSE+ – SENSE – )
VIN (Note 6)
ADIN
l
12
l
TYP
81.92
102.4
2.048
20
25
0.5
l
l
l
l
l
l
l
4151ff
For more information www.linear.com/LTC4151
3
LTC4151
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN is from 7V to 80V, unless noted. (Note 3)
SYMBOL
INL
PARAMETER
Integral Nonlinearity
sT
Transition Noise
fCONV
tCONV
Conversion Rate (Continuous Mode)
Conversion Time (Snapshot Mode)
RADIN
ADIN Pin Input Resistance
(SENSE+ – SENSE – )
ADIN, VIN
ADIN = 3V
IADIN
I2C Interface
VADR(H)
VADR(L)
IADR(IN)
ADIN Pin Input Current
ADIN = 3V
ADR0, ADR1 Input High Threshold
ADRO, ADRI Input Low Threshold
ADRO, ADRI Input Current
CONDITIONS
(SENSE+ – SENSE – )
VIN (Note 5)
ADIN
(SENSE+ – SENSE – )
VIN
ADIN
l
l
l
l
l
2.3
0.2
l
l
±8
l
ADR0, ADR1 = 0V or 3V
ADR0, ADR1 = 0.8V or 2.2V
ISDA, ISDAO, ISDAO = 8mA
SDA, SDAI, SDAO, SDAO, SCL = 5V
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Internal clamps limit the SCL, SDA (LTC4151) and SDAI
(LTC4151-1/LTC4151-2) pins to a minimum of 5.5V. Driving these pins to
voltages beyond the clamp may damage the part. The pins can be safely
tied to higher voltages through a resistor that limits the current below
5mA.
6
53
26
2
TYP
±1
±1
±0.5
1.2
0.3
22
7.5
67
33
10
l
SDA, SDAO, SDAO Output Low Voltage
SDA, SDAI, SDAO, SDAO, SCL Input
Current
SDA, SDAI, SCL Input Threshold
VSDA,SCL(TH)
SDA, SDAI, SCL Clamp Voltage
ISDA , ISDAI, ISCL = 3mA
VSDA,SCL(CL)
2
I C Interface Timing (Note 4)
Maximum SCL Clock Frequency
fSCL(MAX)
Minimum SCL Low Period
tLOW
Minimum SCL High Period
tHIGH
Minimum Bus Free Time Between Stop/
tBUF(MIN)
Start Condition
Minimum Hold Time After (Repeated) Start
tHD,STA(MIN)
Condition
Minimum Repeated Start Condition Set-Up
tSU,STA(MIN)
Time
Minimum Stop Condition Set-Up Time
tSU,STO(MIN)
Minimum Data Hold Time Input
tHD,DATI(MIN)
tHD,DATO(MIN) Minimum Data Hold Time Output
Minimum Data Set-Up Time Input
tSU,DAT(MIN)
Maximum Suppressed Spike
tSP(MAX)
Pulse Width
Stuck-Bus Reset Time
SCL or SDA/SDAI Held Low
tRST
SCL, SDA Input Capacitance
CX
VSDA(OL)
ISDA,SCL(IN)
MIN
l
l
l
l
l
l
l
1.6
5.5
MAX
±3
±3
±2
9
85
42
UNITS
LSB
LSB
LSB
µVRMS
mVRMS
µVRMS
Hz
ms
ms
±2
MW
µA
2.65
0.6
3.0
0.9
±70
0.15
0
0.4
±2
V
V
µA
µA
V
µA
1.8
6.1
2
6.6
V
V
0.65
50
0.12
1.3
600
1.3
kHz
µs
ns
µs
140
600
ns
30
600
ns
30
–100
600
30
110
600
0
900
100
250
ns
ns
ns
ns
ns
10
ms
pF
400
300
50
20
33
5
Note 3: All currents into pins are positive. All voltages are referenced to
GND, unless otherwise noted.
Note 4: Guaranteed by design and not subject to test.
Note 5: Integral nonlinearity and total unadjusted error of VIN are tested
between 7V and 80V.
Note 6: Offset error of VIN is defined by extrapolating the straight line
measured between 7V and 80V.
4151ff
4
For more information www.linear.com/LTC4151
LTC4151
Typical Performance Characteristics
Supply Current vs Supply Voltage
(Normal Mode)
Supply Current vs Supply Voltage
(Shutdown Mode)
400
1.15
– 40°C
SUPPLY CURRENT (µA)
SUPPLY CURRENT (mA)
1.30
25°C
1.00
85°C
0.85
0.70
VIN = 12V, TA = 25°C, unless noted.
40
60
20
SUPPLY VOLTAGE (V)
0
300
25°C
200
85°C
100
0
80
– 40°C
40
60
20
SUPPLY VOLTAGE (V)
0
4151 G01
4151 G02
ADC DNL vs Code (ADIN Voltage)
1.0
0.05
0.5
0.5
–0.05
–0.10
ADC INL (LSB)
1.0
0
0
0
1024
2048
3072
4096
–1.0
0
–0.5
–0.5
0
1024
CODE
2048
3072
4096
–1.0
ADC DNL vs Code (SENSE Voltage)
1
ADC INL (LSB)
1
ADC DNL (LSB)
0.5
0
–1
1024
2048
3072
4096
CODE
–2
0
–1
0
1024
2048
3072
4096
CODE
4151 G06
4096
ADC INL vs Code (SENSE Voltage)
2
–0.5
3072
4151 G05
2
0
2048
CODE
1.0
0
1024
4151 G04
ADC Total Unadjusted Error
vs Code (SENSE Voltage)
–1.0
0
CODE
4151 G03
ADC TOTAL UNADJUSTED ERROR (%)
ADC INL vs Code (ADIN Voltage)
0.10
ADC DNL (LSB)
ADC TOTAL UNADJUSTED ERROR (%)
ADC Total Unadjusted Error
vs Code (ADIN Voltage)
80
–2
0
1024
2048
3072
4096
CODE
4151 G07
4151 G08
4151ff
For more information www.linear.com/LTC4151
5
LTC4151
Typical Performance Characteristics
0.5
SDA, SDAO, SDAO Output Low vs
Pull-Up Current (VSDA(OL) vs ISDA )
6.3
VIN = 12V, TA = 25°C, unless noted.
SDA, SDAI, SCL Clamp Voltage
vs Load Current
85°C
0.4
6.2
0.3
– 40°C
0.2
6.1
– 40°C
6.0
0.1
0
VSDA,SCL(CL) (V)
VSDA(OL) (V)
25°C
25°C
0
5
10
15
20
85°C
5.9
0.01
ISDA (mA)
0.1
1
10
ILOAD (mA)
4151 G09
4151 G10
Pin Functions
ADIN: ADC Input. The onboard ADC measures voltage
range between 0V and 2.048V. Tie to GND if unused.
ADR1, ADR0: I2C Device Address Inputs. Connecting
ADR1 and ADR0 to VIN, GND or leaving the pins open
configures one of nine possible addresses. See Table 1
in the Applications Information section for details.
Exposed Pad (DD Package Only): Exposed pad may be
left open or connected to device ground (GND).
GND: Device Ground.
SCL: I2C Bus Clock Input. Data is shifted in and out at
the SDA pin on rising edges of SCL. This pin is driven
by an open-collector output from a master controller. An
external pull-up resistor or current source is required and
can be placed between SCL and VIN. The voltage at SCL
is internally clamped to 6V (5.5V minimum).
SDA (LTC4151 Only): I2C Bus Data Input/Output. Used
for shifting in address, command or data bits and sending
out data. An external pull-up resistor or current source
is required and can be placed between SDA and VIN.
The voltage at SDA is internally clamped to 6V (5.5V
minimum).
SDAI (LTC4151-1/LTC4151-2 Only): I2C Bus Data Input.
Used for shifting in address, command, data, and SDAO
acknowledge bits. This pin is driven by an open-collector
6
output from a master controller. An external pull-up resistor
or current source is required and can be placed between
SDAI and VIN. If the master separates SDAI and SDAO,
data read at SDAO needs to be echoed back to SDAI for
proper I2C communication. The voltage at SDAI is internally
clamped to 6V (5.5V minimum).
SDAO (LTC4151-2 Only): Serial Bus Data Output. Opendrain output used for sending data back to the master
controller or acknowledging a write operation. Normally
tied to SDAI to form the SDA line. An external pull-up
resistor or current source is required.
SDAO (LTC4151-1 Only): Inverted Serial Bus Data Output. Open-drain output used for sending data back to the
master controller or acknowledging a write operation. Data
is inverted for convenience of opto-isolation. An external
pull-up resistor or current source is required.
SENSE+: Kelvin Sense of the VIN Pin. See Figure 10 for
recommended Kelvin connection.
SENSE–: High Side Current Sense Input. Connect an
external sense resistor between SENSE+ and SENSE–.
The differential voltage between SENSE+ and SENSE– is
monitored by the onboard ADC with a full-scale sense
voltage of 81.92mV.
For more information www.linear.com/LTC4151
4151ff
LTC4151
Pin Functions
SHDN (LTC4151 Only): Shutdown Input. Internally pulled
up to 6.3V. Pull this pin below 1V to force the LTC4151
into shutdown mode. Leave this pin open if unused.
Block Diagram
VIN: Supply Voltage Input. Accepts 7V to 80V. The voltage
at this pin is monitored by the onboard ADC with a fullscale input range of 102.4V. SENSE+ must be connected
to VIN for proper ADC readout.
RS
VIN
2k
SENSE+
SENSE–
6.3V
SHDN
(LTC4151)
ADR1
ADR0
5µA
+
INTERNAL
POWER
–
DECODER
25X
SHUTDOWN
CONTROL
SDAO/SDAO
(LTC4151-1/
LTC4151-2)
VREF = 2.048V
735k
MUX
12-BIT ADC
I2C/
REGISTERS
6V SDA/SDAI
(LTC4151/
LTC4151-1)
15k
6V
GND
SCL
ADIN
4151 BD
Operation
The LTC4151 accurately monitors high side current and
voltages. This device accepts a wide range of input voltages from as low as 7V up to 80V and consumes less
than 1.7mA quiescent current in normal operation. A
shutdown mode is available with the LTC4151 to reduce
the quiescent current to less than 300µA by pulling the
SHDN pin below 1V.
In default continuous scan mode after power-up, the
onboard 12-bit analog-to-digital converter (ADC) continuously and sequentially measures the high side differential
voltage between SENSE+ (Kelvin sense of VIN) and SENSE–
(full-scale 81.92mV) through an internal sense amplifier,
the input voltage VIN (full-scale 102.4V) through an internal
voltage divider, and the voltage applied to the ADIN pin
(full-scale 2.048V). The reference voltage of the ADC is
internally set to 2.048V. The digital data obtained by the
ADC is stored in the onboard registers.
In snapshot mode, the LTC4151 can perform on-demand
measurement of a selected voltage without the need of
continuous polling by a master controller. The snapshot
mode is enabled by programming the control register
through the I2C interface. A status bit in the data register
monitors the ADC’s conversion. When the conversion is
completed, the 12-bit digital code of the measured voltage
is held in the corresponding data registers.
The LTC4151 provides an I2C interface to read the ADC
data from the data registers and to program the control
register. Two three-state pins, ADR0 and ADR1, are
used to decode nine device addresses (see Table 1). The
LTC4151 features a single SDA pin to handle both input
data and output data, while the LTC4151-1/LTC4151-2
provide separate data in (SDAI) and data out (SDAO on
the LTC4151-1 and SDAO on the LTC4151-2) pins to
facilitate opto-isolation.
4151ff
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7
LTC4151
Applications Information
The LTC4151 offers a compact complete solution for high
side power monitoring. With a wide operating voltage
range from 7V to 80V, this device is ideal for a variety of
applications including consumer, automotive, industrial
and telecom infrastructure. The simple application circuit as
shown in Figure 1 provides monitoring of high side current
with a 0.02W resistor (4.096A in full scale), input voltage
(102.4V in full scale) and an external voltage (2.048V in
full scale), all with an internal 12-bit resolution ADC.
Data Converter
The LTC4151 features an onboard, 12-bit ∆Σ A/D
converter (ADC) that continuously monitors three voltages in the sequence of (VSENSE+ – VSENSE–) first, VIN
second and VADIN third. The ∆Σ architecture inherently
averages signal noise during the measurement period.
The differential voltage between SENSE+ and SENSE– is
monitored with an 81.92mV full scale and 20µV resolution that allows accurate measurement of the high side
input current. SENSE+ is a Kelvin sense pin for the VIN
pin and must be connected to VIN (see Figure 10) for
proper ADC readout. The supply voltage at VIN is directly
measured with a 102.4V full scale and 25mV resolution.
The voltage at the uncommitted ADIN pin is measured
with a 2.048V full scale and 0.5mV resolution that allows
monitoring of any external voltage. The 12-bit digital
code of each measured voltage is stored in two adjacent
registers out of the six total data registers A through F,
with the eight MSBs in the first register and the four LSBs
in the second (Table 2).
The data in registers A through F is refreshed at a frequency
of 7.5Hz in continuous scan mode. Setting control register
bit G4 (Table 6) invokes a test mode that halts updating
of these registers so that they can be written to and read
from for software testing.
The data converter features a snapshot mode allowing users to make one-time measurements of a selected voltage
(either the SENSE voltage, VIN voltage, or ADIN voltage).
To enable snapshot mode, set control register bit G7 and
write the 2-bit code of the desired ADC channel to G6
and G5 (Table 6) using a Write Byte command. When the
Write Byte command is completed, the ADC measures the
selected voltage and a Busy Bit in the LSB data register is
set to indicate that the data is not ready. After completing the conversion, the ADC is halted and the Busy Bit is
reset to indicate that the data is ready. To make another
measurement of the same voltage or to measure another
voltage, first disable the snapshot mode for the previous
measurement by clearing control bit G7, then re-enable the
snapshot mode and write the code of the desired voltage
according to the procedure described above. The Busy Bit
remains reset in the continuous scan mode.
0.02Ω
VIN
7V TO 80V
3.3V
VOUT
SENSE+
SENSE–
2k
LTC4151
VIN
VDD
2k
µ-CONTROLLER
SHDN
SCL
SCL
ADR1
SDA
SDA
ADR0
ADIN
VADIN
GND
4151 F01
GND
Figure 1. Monitoring High Side Current and Voltages Using the LTC4151
4151ff
8
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LTC4151
Applications Information
I2C Interface
The LTC4151 features an I2C-compatible interface to
provide access to six ADC data registers and a control
register for monitoring the measured voltages. Figure 2
shows a general data transfer format using the I2C. The
LTC4151is a read-write slave device and supports SMBus
Read Byte, Write Byte, Read Word and Write Word commands. The device also supports Read Page and Write
Page commands that allow one to read or write more than
two bytes of data. When using the Read Page and Write
SDA
a6 - a0
SCL
1-7
Page commands, the host need only to issue an initial
register address and the internal register address pointer
automatically increments by 1 after each byte of data is read
or written. After the register address reaches 06h, it will
be reset to 00h and continue the increment. Upon a Stop
condition, the register address is reset to 00h. If desired,
the Read Page and Write Page support can be disabled by
clearing control register bit G3. The data formats for the
above commands are shown in Figures 3 to 8.
b7 - b0
8
9
1-7
b7 - b0
8
9
1-7
8
9
S
P
START
CONDITION
ADDRESS
R/W
ACK
DATA
ACK
DATA
ACK
STOP
CONDITION
4151 F02
Figure 2. General Data Transfer over I2C
S
ADDRESS W A
COMMAND
1 1 0 a3:a0 0 0
X X X X X b2:b0
FROM MASTER TO SLAVE
FROM SLAVE TO MASTER
S
A DATA A P
0 b7:b0 0
4151 F03
A: ACKNOWLEDGE (LOW)
A: NOT ACKNOWLEDGE (HIGH)
R: READ BIT (HIGH)
ADDRESS W A
COMMAND
1 1 0 a3:a0 0 0
X X X X X b2:b0
A DATA A DATA A P
0 b7:b0 0 b7:b0 0
4151 F04
W: WRITE BIT (LOW)
S: START CONDITION
P: STOP CONDITION
Figure 4. LTC4151 Serial Bus SDA Write Word Protocol
Figure 3. LTC4151 Serial Bus SDA Write Byte Protocol
S
ADDRESS W A
COMMAND
1 1 0 a3:a0 0 0
X X X X X b2:b0
A DATA
A DATA A
...
DATA
0 b7:b0 0 b7:b0 0
...
b7:b0 0
A P
S
ADDRESS W A
COMMAND
1 1 0 a3:a0 0 0
X X X X X b2:b0
A S
ADDRESS
0
1 1 0 a3:a0 1 0 b7:b0 1
R A DATA A P
4151 F05
4151 F06
Figure 5. LTC4151 Serial Bus SDA Write Page Protocol
S
ADDRESS W A
COMMAND
1 1 0 a3:a0 0 0
X X X X X b2:b0
Figure 6. LTC4151 Serial Bus SDA Read Byte Protocol
A S
ADDRESS
0
1 1 0 a3:a0 1 0 b7:b0 0 b7:b0 1
R A DATA A DATA A P
4151 F07
Figure 7. LTC4151 Serial Bus SDA Read Word Protocol
S
ADDRESS W A
COMMAND
1 1 0 a3:a0 0 0
X X X X X b2:b0
A S
ADDRESS
R A DATA A DATA
...
DATA A P
0
1 1 0 a3:a0 1 0 b7:b0 0 b7:b0
...
b7:b0 1
4151 F08
Figure 8. LTC4151 Serial Bus SDA Read Page Protocol
4151ff
For more information www.linear.com/LTC4151
9
LTC4151
Applications Information
Using Opto-Isolators with LTC4151-1 and LTC4151-2
Start and Stop Conditions
The LTC4151-1/LTC4151-2 split the SDA line into SDAI
(input) and SDAO (LTC4151-1 inverted output) or SDAO
(LTC4151-2 output) for convenience of opto-coupling
with a host controller that sits at a different ground level.
When the I2C bus is idle, both SCL and SDA must remain
in the high state. A bus master signals the beginning of a
transmission with a Start condition by transitioning SDA
from high to low while SCL stays high. When the master
has finished communicating with the slave, it issues a Stop
condition by transitioning SDA from low to high while SCL
stays high. The bus is then free for another transmission.
When using opto-isolators with the LTC4151-1, connect
the SDAI to the output of the incoming opto-coupler and
connect the SDAO to the anode of the outgoing optocoupler (see Figure 9). With the outgoing opto-coupler
clamping SDAO and internal 6V (5.5V minimum) clamps
on SDAI and SCL, the pull-up resistors on these three pins
can be directly connected to VIN. In this way (with SDAO
rather than conventional SDAO), the need for a separate
low voltage supply for pull-ups is eliminated.
Figure 11 shows the LTC4151-2 with high speed optocouplers for faster bus speeds. The LTC4151-2 has a noninverter SDAO output. Powered from VIN, the high voltage
LT3010-5 low dropout regulator provides the supply for the
opto-couplers as well as the bus lines pull-up. If the SDAI
and SDAO on the master controller are not tied together,
the ACK bit of the SDAO must be returned back to SDAI.
Stuck-Bus Reset
The LTC4151 I2C interface features a stuck-bus reset
timer. The low conditions of the SCL and the SDA/SDAI
pins are OR’ed to start the timer. The timer is reset when
both SCL and SDA/SDAI are pulled high. If the SCL pin or
the SDA/SDAI pin is held low for over 33ms, the stuck-bus
timer will expire and the internal I2C state machine will be
reset to allow normal communication after the stuck-bus
condition is cleared. The stuck-bus timer can be disabled
by clearing control register bit G2.
RS
0.02Ω
VIN
48V
SENSE+
3.3V
SENSE–
SCL
R1
20k
SDAI
ADR1
SDA0
ADR0
ADIN
GND
R3
5.1k
8
VIN
LTC4151-1
R2
20k
VADIN
MOCD207M
1
7
6
2
3
5
4
1
MOCD207M
8
R4
0.51k
R5
0.51k
R6
10k
R7
10k
SCL
VDD
µ-CONTROLLER
SDA
GND
4151 F09
2
3
7
6
4
5
Figure 9. Opto-Isolation of the I2C Interface Between LTC4151-1 and a
Microcontroller (1.5kHz Data Rate of I2C is Limited by Slew Rate of Opto-Isolators)
4151ff
10
For more information www.linear.com/LTC4151
LTC4151
Applications Information
I2C Device Addressing
Nine distinct I2C bus addresses are configurable using the
three-state pins ADR0 and ADR1, as shown in Table 1.
Address bits a6, a5 and a4 are configured to (110) and
the least significant bit is the R/W bit. In addition, the
LTC4151 will respond to a mass write address (1100 110)
b for writing to all LTC4151s, regardless of their individual
address settings.
Acknowledge
The acknowledge signal is used for handshaking between
the transmitter and the receiver to indicate that the last
byte of data was received. The transmitter always releases
the SDA line during the acknowledge clock pulse. The
LTC4151 pulls the SDA line low on the 9th clock cycle to
acknowledge receipt of the data. If the slave fails to acknowledge by leaving SDA high, then the master can abort
the transmission by generating a Stop condition. When
the master is receiving data from the slave, the master
must pull down the SDA line during the clock pulse to
indicate receipt of a data byte, and that another byte is to
be read. After the last byte has been received the master
will leave the SDA line high (not acknowledge) and issue
a Stop condition to terminate the transmission.
Write Protocol
The master begins a write operation with a Start condition
followed by the seven bit slave address and the R/W bit
set to zero. After the addressed LTC4151 acknowledges
the address byte, the master then sends a command
byte which indicates which internal register the master
wishes to write. The LTC4151 acknowledges this and
then latches the lower three bits of the command byte
into its internal register address pointer. The master then
delivers the data byte and the LTC4151 acknowledges
once more and latches the data into its internal register.
If the master continues sending a second byte or more
data bytes, as in a Write Word or Write Page command,
the second byte or more data bytes will be acknowledged
by the LTC4151, the internal register address pointer
will increment automatically, and each byte of data will
be latched into an internal register corresponding to the
address pointer. The write operation terminates and the
register address pointer resets to 00h when the master
sends a Stop condition.
Read Protocol
The master begins a read operation with a Start condition
followed by the seven bit slave address and the R/W bit
set to zero. After the addressed LTC4151 acknowledges
the address byte, the master then sends a command
byte that indicates which internal register the master
wishes to read. The LTC4151 acknowledges this and then
latches the lower three bits of the command byte into its
internal register address pointer. The master then sends
a repeated Start condition followed by the same seven bit
Table 1. LTC4151 Device Addressing*
DESCRIPTION
HEX DEVICE
ADDRESS
LTC4151
ADDRESS PINS
BINARY DEVICE ADDRESS
h
a6
a5
Mass Write
CC
1
1
0
CE
1
1
1
D0
1
1
2
D2
1
1
3
D4
1
1
4
D6
1
1
5
D8
1
1
6
DA
1
1
7
DC
1
1
8
DE
1
1
*H = Tie High; L = Tie to GND; NC = Open; X = Don’t Care
a4
0
0
0
0
0
0
0
0
0
0
a3
0
0
1
1
1
1
1
1
1
1
a2
1
1
0
0
0
0
1
1
1
1
a1
1
1
0
0
1
1
0
0
1
1
a0
0
1
0
1
0
1
0
1
0
1
R/W
0
X
X
X
X
X
X
X
X
X
ADR1
X
H
NC
H
NC
NC
L
H
L
L
ADR0
X
L
H
H
NC
L
H
NC
NC
L
4151ff
For more information www.linear.com/LTC4151
11
LTC4151
Applications Information
Table 2. LTC4151 Register Address and Contents
REGISTER ADDRESS*
REGISTER NAME
READ/WRITE
00h
SENSE (A)
R/W**
ADC Current Sense Voltage Data (8 MSBs)
01h
SENSE (B)
R/W**
ADC Current Sense Voltage Data (4 LSBs)
02h
VIN (C)
R/W**
ADC VIN Voltage Data (8 MSBs)
03h
VIN (D)
R/W**
ADC VIN Voltage Data (4 LSBs)
04h
ADIN (E)
R/W**
ADC ADIN Voltage Data (8 MSBs)
05h
ADIN (F)
R/W**
ADC ADIN Voltage Data (4 LSBs)
06h
CONTROL (G)
07h
Reserved
R/W
DESCRIPTION
Controls ADC Operation Mode and Test Mode
*Register address MSBs b7-b3 are ignored. **Writable if bit G4 is set.
Table 3. SENSE Registers A (00h) and B (O1h)—Read/Write
BIT
NAME
OPERATION
A7:0, B7:4
SENSE Voltage Data
12-Bit Data of Current Sense Voltage with 20µV LSB and 81.92mV Full-Scale
B3
ADC Busy in Snapshot Mode
1 = SENSE Being Converted; 0 = SENSE Conversion Completed. Not Writable
B2:0
Reserved
Always Returns 0. Not Writable
Table 4. VIN Registers C (02h) and D (O3h)—Read/Write
BIT
NAME
OPERATION
C7:0, D7:4
VIN Voltage Data
12-Bit Data of VIN Voltage with 25mV LSB and 102.4V Full-Scale
D3
ADC Busy in Snapshot Mode
1 = VIN Being Converted; 0 = VIN Conversion Completed. Not Writable
D2:0
Reserved
Always Returns 0, Not Writable
Table 5. ADIN Registers E (04h) and F (O5h)—Read/Write
BIT
NAME
OPERATION
E7:0, F7:4
ADIN Voltage Data
12-Bit Data of Current Sense Voltage with 500µV LSB and 2.048V Full-Scale
F3
ADC Busy in Snapshot Mode
1 = ADIN Being Converted; 0 = ADIN Conversion Completed. Not Writable
F2:0
Reserved
Always Returns 0, Not Writable
Table 6. CONTROL Register G (06h)—Read/Write
BIT
NAME
OPERATION
G7
ADC Snapshot Mode
Enable
G6
ADC Channel Label for
Snapshot Mode
ADC Channel Label for
Snapshot Mode
Enables ADC Snapshot Mode; 1 = Snapshot Mode Enabled. Only the channel selected by G6 and G5 is
measured by the ADC. After the conversion, the channel busy bit is reset and the ADC is halted.
0 = Snapshot Mode Disabled (ADC free running, Default).
ADC Channel Label for Snapshot Mode
G5
G6
0
0
1
G5
0
1
0
ADC CHANNEL
SENSE (Default)
VIN
ADIN
G4
Test Mode Enable
G3
Page Read/Write Enable
Test Mode Halts ADC Operation and Enables Writes to ADC Registers; 1 = Enable Test Mode,
0 = Disable Test Mode (Default)
Enables Page Read/Write; 1 = Enable I2C Page Read/Write (Default), 0 = Disable I2C Page Read/Write
G2
Stuck-Bus Timer Enable
Enables I2C Stuck-Bus Reset Timer; 1 = Enable Stuck-Bus Timer (Default), 0 = Disable Stuck-Bus Timer
G1:0
Reserved
Always Returns 0, Not Writable
4151ff
12
For more information www.linear.com/LTC4151
LTC4151
Applications Information
address with the R/W bit now set to one. The LTC4151
acknowledges and sends the contents of the requested
register. The transmission terminates when the master
sends a Stop condition. If the master acknowledges the
transmitted data byte, as in a Read Word command, the
LTC4151 will send the contents of the next register. If
the master acknowledges the second data byte and each
of the following (if more) data bytes, as in a Read Page
command, the LTC4151 will keep sending out each data
byte in the register that corresponds to the incrementing
register pointer. The read operation terminates and the
register address pointer resets to 00h when the master
sends a Stop condition.
stays at a reasonable temperature. Using 0.03" per amp
or wider is recommended. Note that 1oz copper exhibits
a sheet resistance of about 530µW per square.
VIN
ILOAD
RS
SENSE+
VIN
ADR1
SENSE–
GND
LTC4151
ADR0
Layout Considerations
A Kelvin connection between the sense resistor RS and
the LTC4151 is recommended to achieve accurate current sensing (Figure 10). The minimum trace width for
1oz copper foil is 0.02" per amp to make sure the trace
ILOAD
GND
4151 F10
Figure 10. Recommended Layout for Kelvin Connection
R1
0.02Ω
VIN
7V TO 80V
VIN
VOUT
+
SENSE
VIN
ADIN
SENSE–
LTC4151-2
SDAO
ADIN
ADR1
SDAI
ADR0
SCL
GND
1
IN
OUT
LT3010-5
C7
1µF 5 SHDN SENSE 2
100V
GND
4
ISO1
PS9817-2
8
C6
1µF
R8
1k
R3
10k
R4
10k
VCC
1
8
7
2
GND 5
8
1
7
VCC
6
5 GND
5V
C4
0.1µF R12
1k
R11
1k
R14
10k
R13
10k
2
ISO_SDA
3
ISO_SCL
4
4151 F11
ISO2
PS9817-2
Figure 11. LTC4151-2 I2C Opto-Isolation Interface with High Speed Opto-Couplers
4151ff
For more information www.linear.com/LTC4151
13
LTC4151
Typical Application
Temperature Monitoring with an NTC Thermistor While
Measuring Load Current and LTC4151 Supply Current
0.2Ω
VIN
48V
VISHAY
2381 615 4.104
100k AT 25°C
1%
SENSE+
SENSE –
250mA
LOAD
VIN
SCL
I2C
40.2k
1%
LTC4151
ADIN
SDA
ADR1
1.5k
1%
GND
ADR0
4151 TA02
T(°C) = 58.82 • (NADIN /NVIN – 0.1066), 20°C < T < 60°C.
NADIN AND NVIN ARE DIGITAL CODES MEASURED BY THE
ADC AT THE ADIN AND VIN PINS, RESPECTIVELY.
LTC4151-1 Monitors Current and Input Voltage of a –48V System and Interfaces with
a Microcontroller (1.5kHz Data Rate of I2C is Limited by Slew Rate of Opto-Isolators)
RS
0.02Ω
RTN
SENSE+
3.3V
SENSE–
SCL
R1
20k
SDAI
ADR1
SDA0
ADR0
ADIN
GND
R3
5.1k
8
VIN
LTC4151-1
R2
20k
VADIN
MOCD207M
1
7
6
2
3
5
4
1
MOCD207M
8
R4
0.51k
R5
0.51k
R6
10k
R7
10k
SCL
VDD
µ-CONTROLLER
SDA
GND
4151 TA04
–48V
2
3
7
6
4
5
4151ff
14
For more information www.linear.com/LTC4151
LTC4151
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699 Rev C)
R = 0.125
TYP
6
0.40 ± 0.10
10
0.70 ±0.05
3.55 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
3.00 ±0.10
(4 SIDES)
1.65 ± 0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
PIN 1
PACKAGE
TOP MARK
OUTLINE (SEE NOTE 6)
0.25 ± 0.05
5
0.75 ±0.05
0.200 REF
0.50
BSC
2.38 ±0.05
(2 SIDES)
0.00 – 0.05
1
(DD) DFN REV C 0310
0.25 ± 0.05
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
MS Package
10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661 Rev F)
0.889 ±0.127
(.035 ±.005)
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
3.00 ±0.102
(.118 ±.004)
(NOTE 3)
0.50
0.305 ±0.038
(.0197)
(.0120 ±.0015)
BSC
TYP
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
10 9 8 7 6
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
DETAIL “A”
0.497 ±0.076
(.0196 ±.003)
REF
0° – 6° TYP
GAUGE PLANE
1 2 3 4 5
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.86
(.034)
REF
1.10
(.043)
MAX
0.17 – 0.27
(.007 – .011)
TYP
0.50
(.0197)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.1016 ±0.0508
(.004 ±.002)
MSOP (MS) 0213 REV F
4151ff
For more information www.linear.com/LTC4151
15
LTC4151
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
S Package
16-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
.386 – .394
(9.804 – 10.008)
NOTE 3
.045 ±.005
.050 BSC
16
N
14
13
12
11
10
9
N
.245
MIN
.160 ±.005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
1
.030 ±.005
TYP
15
2
3
N/2
N/2
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
× 45°
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
1
2
3
4
5
.053 – .069
(1.346 – 1.752)
NOTE:
1. DIMENSIONS IN
.014 – .019
(0.355 – 0.483)
TYP
7
8
.004 – .010
(0.101 – 0.254)
0° – 8° TYP
.016 – .050
(0.406 – 1.270)
6
.050
(1.270)
BSC
S16 REV G 0212
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
4151ff
16
For more information www.linear.com/LTC4151
LTC4151
Revision History
(Revision history begins at Rev C)
REV
DATE
DESCRIPTION
C
11/10
Added H-grade information
PAGE NUMBER
2, 3
Revised order of Pin Functions section and added information to SDAI pin description
6
Added diode and 2k resistor to Block Diagram
7
Added information to Application Information section
10
D
7/12
Changed part number in Pin Configuration section from LT4151 to LTC4151
2
E
11/12
Added –48V application schematic
14
F
3/14
Increased VADR(H) MAX limit and decreased VADR(L) MIN limit
4
4151ff
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representaFor more
information
www.linear.com/LTC4151
tion that the interconnection
of its circuits
as described
herein will not infringe on existing patent rights.
17
LTC4151
Typical Application
High Side Current, Input Voltage and Open Fuse Monitoring
with a Single LTC4151
VIN1
48V
F1
D1
F2
D2
RS
0.02Ω
VIN2
48V
D3
D4
R1
150k
R2
301k
SENSE+
SENSE–
VIN
SCL
V+
I2C
LTC4151
LOAD
ADR1
ADIN
R3
3.4k
SDA
V–
ADR0
GND
GND
4151 TA03
CONDITION
RESULT
NADIN ≥ 1.375 • NVIN
Normal Operation
0.835 • NVIN ≤ NADIN < 1.375 • NVIN
F2 is Open
0.285 • NVIN ≤ NADIN < 0.835 • NVIN
F1 is Open
(Not Responding)
Both F1 and F2 are Open
VIN1 AND VIN2 ARE WITHIN 20% APART. NADIN AND NVIN ARE DIGITAL CODES
MEASURED BY THE ADC AT THE ADIN AND VIN PINS, RESPECTIVELY.
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LT2940
Power and Current Monitor
Four-Quadrant Multiplication, ±5% Power Accuracy, 4V to 80V Operation
LTC2945
Wide Range I2C Power Monitor
0V to 80V Input Range, 2.7V to 80V Supply Range, Shunt Regulator, 12-Bit ADC
with ±0.75% TUE
LTC2451
16-Bit I2C Ultra Tiny Delta Sigma ADC
Single-Ended Input, 0 to VCC Input Range, 60Hz Output Rate, 3mm × 2mm
DFN-8 Package
LTC2453
16-Bit I2C Ultra Tiny Delta Sigma ADC
Differential Input, ±VCC Input Range, 60Hz Output Rate, 3mm × 2mm
DFN-8 Package
LTC2970
Power Supply Monitor and Margining Controller
14-Bit ADC Monitoring Current and Voltages, Supplies from 8V to 15V
Controller with ADC and I2C
8-Bit ADC Monitoring Current and Voltages, Supplies from 2.9V to 15V
TM
LTC4215
Positive Hot Swap
LTC4260
Positive High Voltage Hot Swap Controller with
ADC and I2C
8-Bit ADC Monitoring Current and Voltages, Supplies from 8.5V to 80V
LTC4261/
LTC4261-2
Negative High Voltage Hot Swap Controller with
ADC and I2C
10-Bit ADC Monitoring Current and Voltages, Supplies from –12V
LTC6101/
LTC6101HV
High Voltage, High Side Current Sense Amplifier
in SOT-23 Package
Supplies from 4V to 60V (LTC6101) and 5V to 100V (LTC6101HV)
4151ff
18 Linear Technology Corporation
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