Datasheet LTC4151, LTC4151-1, LTC4151CS-2, LTC4151IS-2 Datasheet (Linear)

LTC4151

High Voltage I2C Current

and Voltage Monitor

FEATURES

n

Wide Operating Voltage Range: 7V to 80V

n

12-Bit Resolution for Both Current and Voltages

n

I2C Interface

n

Additional ADC Input Monitors an External Voltage

n

Continuous Scan and Snapshot Modes

n

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

APPLICATIONS

n

Telecom Infrastructure

n

Automotive

n

Industrial

n

Consumer

DESCRIPTION

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 I
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 I
drive opto-isolators. The data out on the LTC4151-1 is
inverted while that on the LTC4151-2 is not.

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 of Linear
Technology Corporation. All other trademarks are the property of their respective owners.

2

C interface when polled

2

C data pins to

TYPICAL APPLICATION

High Side Power Sensing with Onboard ADC and I2C

V

IN

ADR1

ADR0

SENSE

0.02Ω

+

LTC4151

GND

SENSE

–

SHDN

SCL

SDA

ADIN

V

OUT

V

7V to 80V

IN

MEASURED
VOLTAGE

2k 2k

μCONTROLLER

SCL

SDA

3.3V

V

4151 TA01

12-Bit ADC DNL and INL

1.0

0.5

0

ADC DNL (LSB)

DD

–0.5

–1.0

0

1.0

0.5

0

ADC INL (LSB)

–0.5

–1.0

0

1024

1024

2048
CODE

2048
CODE

3072

3072

4096

4151 TA01b

4096

4151 TA01c

4151fb

1

LTC4151

ABSOLUTE MAXIMUM RATINGS

VIN Voltage ................................................. –0.3V to 90V

SENSE

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

+

, SENSE– Voltages .......................... VIN – 10V or

–0.3V to V

IN

(Notes 1, 3)

+ 0.3V

Operating Temperature Range

LTC4151C/LTC4151C-1/LTC4151C-2 ........ 0°C to 70°C

LTC4151I/LTC4151I-1/LTC4151I-2 .......–40°C to 85°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 LT4151

SENSE

V

IN

ADR1

ADR0

ADIN

10-LEAD (3mm s 3mm) PLASTIC DFN

EXPOSED PAD (PIN 11) PCB GND CONNECTION OPTIONAL

LTC4151-1 LTC4151-1

TOP VIEW

+

1

2

3

4

5

DD PACKAGE

T

= 125°C, θJA = 45°C/W

JMAX

TOP VIEW

9

8

7

6

SENSE

GND

SHDN

SDA

SCL

–

10

11

+

SENSE

1

V

2

IN

ADR1

3

ADR0

4

ADIN

5

10-LEAD PLASTIC MSOP

T

JMAX

TOP VIEW

10
9
8
7
6

MS PACKAGE

= 125°C, θJA = 85°C/W

SENSE
GND

SHDN

SDA
SCL

–

LTC4151-2

9

8

7

6

SENSE

GND

SDAO

SDAI

SCL

–

SENSE

+

SENSE

1

V

2

IN

ADR1

ADR0

ADIN

10-LEAD (3mm s 3mm) PLASTIC DFN

T

EXPOSED PAD (PIN 11) PCB GND CONNECTION OPTIONAL

JMAX

11

3

4

5

DD PACKAGE

= 125°C, θJA = 45°C/W

10

+

1

2

V

IN

3

NC

4

NC

5

ADR1

6

NC

7

ADR0

8

NC

16-LEAD PLASTIC SO

T

JMAX

TOP VIEW

16

15

14

13

12

11

10

9

S PACKAGE

= 150°C, θJA = 100°C/W

SENSE

NC

NC

GND

SDAO

SDAI

SCL

ADIN

TOP VIEW

+

SENSE

1

V

2

IN

ADR1

3

ADR0

4

ADIN

5

MS PACKAGE

10-LEAD PLASTIC MSOP

T

= 125°C, θJA = 85°C/W

JMAX

–

10
9
8
7
6

SENSE
GND

SDAO

SDAI
SCL

–

2

4151fb

LTC4151

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC4151CDD#PBF LTC4151CDD#TRPBF LCWZ 10-Lead (3mm x 3mm) Plastic DFN 0°C to 70°C

LTC4151IDD#PBF LTC4151IDD#TRPBF LCWZ 10-Lead (3mm x 3mm) Plastic DFN –40°C to 85°C

LTC4151CDD-1#PBF LTC4151CDD-1#TRPBF LCXC 10-Lead (3mm x 3mm) Plastic DFN 0°C to 70°C

LTC4151IDD-1#PBF LTC4151IDD-1#TRPBF LCXC 10-Lead (3mm x 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

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 specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based fi nish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/

The l denotes the specifi cations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifi cations are at TA = 25°C. VIN is from 7V to 80V, unless noted. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

General

V

IN

I

IN

I

SENSE

I

SENSE

V

SHDN(TH)

I

SHDN

+

–

Supply Voltage

Supply Current VIN = 48V, Normal Operation Mode

V

= 12V, Shutdown Mode

IN

SENSE+ Input Current VIN, SENSE+, SENSE– = 48V

SENSE– Input Current VIN, SENSE+, SENSE– = 48V

SHDN Input Threshold

SHDN Input Current SHDN = 0V

ADC

RES Resolution (No Missing Codes) (Note 4)

V

FS

Full-Scale Voltage (SENSE+ – SENSE–)

V

IN

ADIN

LSB LSB Step Size (SENSE

+

IN

– SENSE–)
V
ADIN

TUE Total Unadjusted Error (SENSE+ – SENSE–)

V

(Note 5)

IN

ADIN, LTC4151C, LTC4151C-1, LTC4151C-2
ADIN, LTC4151I, LTC4151I-1, LTC4151I-2

V

OS

Offset Error (SENSE+ – SENSE–)

V

(Note 6)

IN

ADIN

V

(Note 5)

IN

+

– SENSE–)

INL Integral Nonlinearity (SENSE

ADIN

l

780V

l
l

l

l

l

1 1.5 2 V

l

–3 –5 –8 μA

l

12 Bits

1.2

120

1.7

300

mA

μA

59 μA

0.1 1 μA

81.92

mV

102.4

2.048

20
25

0.5

l
l
l
l

l
l
l

l
l
l

±1
±1

±0.5

±1.25

±1

±0.75

±1

±5
±6
±8

±3
±3
±2

μV
mV
mV

LSB
LSB
LSB

LSB
LSB
LSB

V
V

%
%
%
%

4151fb

3

LTC4151

ELECTRICAL CHARACTERISTICS

The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

σ

T

f

CONV

t

CONV

R

ADIN

I

ADIN

2

C Interface

I

V

ADR(H)

V

ADR(L)

I

ADR(IN)

V

SDA(OL)

I

SDA,SCL(IN)

V

SDA,SCL(TH)

V

SDA,SCL(CL)

2

C Interface Timing (Note 4)

I

f

SCL(MAX)

t

LOW

t

HIGH

t

BUF(MIN)

t

HD,STA(MIN)

t

SU,STA(MIN)

t

SU,STO(MIN)

t

HD,DATI(MIN)

t

HD,DATO(MIN)

t

SU,DAT(MIN)

t

SP(MAX)

t

RST

C

X

Transition Noise (SENSE+ – SENSE–)

Conversion Rate (Continuous Mode)

Conversion Time (Snapshot Mode) (SENSE+ – SENSE–)

ADIN Pin Input Resistance ADIN = 3V

ADIN Pin Input Current ADIN = 3V

ADR0, ADR1 Input High Threshold

ADRO, ADRI Input Low Threshold

ADRO, ADRI Input Current ADR0, ADR1 = 0V or 3V

SDA, SDAO, SDAO Output Low Voltage I

SDA, SDAI, SDAO, SDAO, SCL Input

Current

SDA, SDAI, SCL Input Threshold

SDA, SDAI, SCL Clamp Voltage I

Maximum SCL Clock Frequency 400 kHz

Minimum SCL Low Period 0.65 1.3 μs

Minimum SCL High Period 50 600 ns

Minimum Bus Free Time Between Stop/
Start Condition

Minimum Hold Time After (Repeated) Start
Condition

Minimum Repeated Start Condition Set-Up
Time

Minimum Stop Condition Set-Up Time 30 600 ns

Minimum Data Hold Time Input –100 0 ns

Minimum Data Hold Time Output 300 600 900 ns

Minimum Data Set-Up Time Input 30 100 ns

Maximum Suppressed Spike

Pulse Width

Stuck-Bus Reset Time SCL or SDA/SDAI Held Low 20 33 ms

SCL, SDA Input Capacitance 510 pF

= 25°C. VIN is from 7V to 80V, unless noted. (Note 3)

A

V

IN

ADIN

l

6 7.5 9 Hz

l

53

ADIN, V

IN

ADR0, ADR1 = 0.8V or 2.2V

, I

, I

SDA

SDAO

SDAO

= 8mA

SDA, SDAI, SDAO, SDAO, SCL = 5V

, I

, I

SDA

SDAI

SCL

= 3mA

l

26

l

210

l

l

2.3 2.65 2.9 V

l

0.3 0.6 0.9 V

l
l

±8

l

l

l

1.6 1.8 2 V

l

5.5 6.1 6.6 V

50 110 250 ns

1.2

0.3
22

67
33

85
42

μV

mV

μV

RMS
RMS
RMS

ms
ms

MΩ

±2 μA

±70 μA

μA

0.15 0.4 V

0±2 μA

0.12 1.3 μs

140 600 ns

30 600 ns

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.

4

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 V

are tested

IN

between 7V and 80V.
Note 6: Offset error of V

is defi ned by extrapolating the straight line

IN

measured between 7V and 80V.

4151fb

LTC4151

TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Supply Voltage
(Normal Mode)

1.30

1.15

1.00

SUPPLY CURRENT (mA)

0.85

0.70
0

ADC Total Unadjusted Error
vs Code (ADIN Voltage)

0.10

– 40°C

25°C

85°C

20

40

SUPPLY VOLTAGE (V)

60

80

4151 G01

ADC DNL vs Code (ADIN Voltage)

1.0

400

300

200

SUPPLY CURRENT (μA)

100

0

= 12V, TA = 25°C, unless noted.

V

IN

Supply Current vs Supply Voltage
(Shutdown Mode)

– 40°C

25°C

85°C

0

20

40

SUPPLY VOLTAGE (V)

60

4151 G02

ADC INL vs Code (ADIN Voltage)

1.0

80

0.05

0

–0.05

ADC TOTAL UNADJUSTED ERROR (%)

–0.10

0

1024

2048

CODE

3072

4151 G03

4096

0.5

0

ADC DNL (LSB)

–0.5

–1.0

0

1024

2048
CODE

3072

4096

4151 G04

0.5

0

ADC INL (LSB)

–0.5

–1.0

0

1024

2048
CODE

ADC Total Unadjusted Error
vs Code (SENSE Voltage) ADC DNL vs Code (SENSE Voltage) ADC INL vs Code (SENSE Voltage)

1.0

0.5

0

–0.5

ADC TOTAL UNADJUSTED ERROR (%)

–1.0

0

1024

2048
CODE

3072

4151 G06

4096

2

1

0

ADC DNL (LSB)

–1

–2

0

1024

2048
CODE

3072

4096

4151 G07

2

1

0

ADC INL (LSB)

–1

–2

0

1024

2048
CODE

3072

3072

4096

4151 G05

4096

4151 G08

4151fb

5

LTC4151

TYPICAL PERFORMANCE CHARACTERISTICS

SDA, SDAO, SDAO Output Low vs
Pull-Up Current (V

0.5

0.4

0.3

(V)

SDA(OL)

0.2

V

0.1

0

0

I

SDA

10

(mA)

5

SDA(OL)

vs I

15

SDA

85°C

25°C

– 40°C

4151 G09

)

20

6.3

6.2

(V)

6.1

SDA,SCL(CL)

V

6.0

5.9

0.01 0.1 1 10

PIN FUNCTIONS

SENSE+: Kelvin Sense of the VIN Pin. See Figure 10 for
recommended Kelvin connection.

: Supply Voltage Input. Accepts 7V to 80V. The voltage

V

IN

at this pin is monitored by the onboard ADC with a full-

+

scale input range of 102.4V. SENSE

for proper ADC readout.

to V

IN

2

ADR1, ADR0: I
ADR1 and ADR0 to V

C Device Address Inputs. Connecting

, GND or leaving the pins open

IN

must be connected

confi gures one of nine possible addresses. See Table 1
in the Applications Information section for details.

ADIN: ADC Input. The onboard ADC measures voltage
range between 0V and 2.048V. Tie to GND if unused.

2

SCL: I

C 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 V

. The voltage at SCL

IN

is internally clamped to 6V (5.5V minimum).

2

SDA (LTC4151 Only): I

C 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 V
The voltage at SDA is internally clamped to 6V (5.5V
minimum).

SDAI (LTC4151-1/LTC4151-2 Only): I
Used for shifting in address, command or data bits. 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 SDAI and V
age 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 Out-
put. 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.

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.

VIN = 12V, TA = 25°C, unless noted.

SDA, SDAI, SCL Clamp Voltage
vs Load Current

– 40°C

25°C

85°C

I

(mA)

LOAD

4151 G10

2

C Bus Data Input.

. The volt-

IN

IN

.

6

4151fb

PIN FUNCTIONS

LTC4151

GND: Device Ground.

–

SENSE

external sense resistor between SENSE
The differential voltage between SENSE

BLOCK DIAGRAM

: High Side Current Sense Input. Connect an

+

+

and SENSE– is

R

SENSE

+

25X

S

+

V

IN

V

IN

INTERNAL
POWER

735k

15k

GND ADIN

and SENSE–.

–

SENSE

–

MUX

monitored by the onboard ADC with a full-scale sense
voltage of 81.92mV.

Exposed Pad (DD Package Only): Exposed pad may be
left open or connected to device ground (GND).

6.3V

SHDN

(LTC4151)

5μA

SHUTDOWN

CONTROL

V

REF

12-BIT ADC

= 2.048V

ADR1

DECODER

2

I

C/

REGISTERS

ADR0

SDAO/SDAO
(LTC4151-1/

LTC4151-2)

SDA/SDAI

6V

(LTC4151/

LTC4151-1)

6V

SCL

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

–

SENSE

(full-scale 81.92mV) through an internal sense
amplifi er, the input voltage V
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.

+

(Kelvin sense of VIN) and

(full-scale 102.4V) through

IN

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

2

through the I

C 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.

2

The LTC4151 provides an I

C 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.

4151fb

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 0.02Ω 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 ΔΣ A/D con­verter (ADC) that continuously monitors three voltages
in the sequence of (V
and V

third. The ΔΣ architecture inherently aver-

ADIN

SENSE

– V

+

–

) fi rst, VIN second

SENSE

ages 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
pin and must be connected to V
proper ADC readout. The supply voltage at V

+

is a Kelvin sense pin for the VIN

(see Figure 10) for

IN

is directly

IN

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 fi rst 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, V

voltage, or ADIN voltage).

IN

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, fi rst 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.

8

V

IN

ADR1

ADR0

SENSE

0.02Ω

+

LTC4151

GND

SENSE

–

SHDN

SCL

SDA

ADIN

V

OUT

2k 2k

V

ADIN

μ-CONTROLLER

SCL

SDA

V

IN

7V TO 80V

Figure 1. Monitoring High Side Current and Voltages Using the LTC4151

3.3V

V

DD

4151 F01

4151fb

APPLICATIONS INFORMATION

LTC4151

I2C Interface

2

The LTC4151 features an I

C-compatible interface to
provide access to six ADC data registers and a control
register for monitoring the measured voltages. Figure 2

2

shows a general data transfer format using the I

C. 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

SCL

S

START

CONDITION

a6 - a0 b7 - b0 b7 - b0

1 - 7 8 9

ADDRESS R/W ACK DATA ACK DATA ACK

1 - 7 8 9 1 - 7 8 9

Figure 2. General Data Transfer over I2C

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.

P

STOP

CONDITION

4151 F02

S ADDRESS

1 1 0 a3:a0

FROM MASTER TO SLAVE

FROM SLAVE TO MASTER

COMMAND DATA

A A AP

X X X X X b2:b00W000b7:b0

A: ACKNOWLEDGE (LOW)
A: NOT ACKNOWLEDGE (HIGH)
R: READ BIT (HIGH)

4151 F03

W: WRITE BIT (LOW)
S: START CONDITION
P: STOP CONDITION

Figure 3. LTC4151 Serial Bus SDA Write Byte Protocol

S ADDRESS

1 1 0 a3:a0

COMMAND

A A AP

DATA

b7:b0

A

0

DATA0A

b7:b0

Figure 5. LTC4151 Serial Bus SDA Write Page Protocol

S ADDRESS

1 1 0 a3:a0 1 1 0 a3:a0 1 0

A

X X X X X b2:b00W00

Figure 7. LTC4151 Serial Bus SDA Read Word Protocol

S ADDRESS

1 1 0 a3:a0 1 1 0 a3:a0 1 0

COMMAND S ADDRESS R A

A

X X X X X b2:b00W00

Figure 8. LTC4151 Serial Bus SDA Read Page Protocol

S ADDRESS

1 1 0 a3:a0

A

Figure 4. LTC4151 Serial Bus SDA Write Word Protocol

...

DATA

b7:b0

0X X X X X b2:b00W00

4151 F05

...

S ADDRESS

1 1 0 a3:a0 1 1 0 a3:a0 1 0

A A A P

X X X X X b2:b00W00

Figure 6. LTC4151 Serial Bus SDA Read Byte Protocol

COMMAND S ADDRESS R A

A A P

A A P

DATA

0Ab7:b0

b7:b0 1

DATA

b7:b0 1

DATA

0Ab7:b0

COMMAND DATA DATA

X X X X X b2:b00W0000

COMMAND S ADDRESS R A

DATA

...

...

A A AP

4151 F07

DATA

b7:b0

4151 F08

b7:b0b7:b0

4151 F04

DATA

b7:b0 1

4151 F06

4151fb

9

LTC4151

APPLICATIONS INFORMATION

Using Opto-Isolators with LTC4151-1 and LTC4151-2

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 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 V

. In this way (with SDAO

IN

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.

Start and Stop Conditions

2

When the I

C 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 fi nished 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.

Stuck-Bus Reset

2

The LTC4151 I

C 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 I

2

C 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.

V

48V

R

S

V

IN

ADR1

ADR0

SENSE

LTC4151-1

0.02Ω

+

GND

SENSE

–

SCL

SDAI

SDA0

ADIN

R1
20kR220kR35.1k

V

ADIN

MOCD207M

MOCD207M

R5

R4

0.51kR610kR710k

0.51k

18

27
36

45

81

72
63

54

IN

3.3V

V

DD

SCL

μ-CONTROLLER

SDA

4151 F09

Figure 9. Opto-Isolation of the I2C Interface Between LTC4151-1 and a
Microcontroller (Data Rate of I2C is Limited by Slew Rate of Opto-Isolators)

10

4151fb

APPLICATIONS INFORMATION

LTC4151

I2C Device Addressing

Nine distinct I

2

C bus addresses are confi gurable using the
three-state pins ADR0 and ADR1, as shown in Table 1.
Address bits a6, a5 and a4 are confi gured to (110) and
the least signifi cant 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*

HEX DEVICE

DESCRIPTION

Mass Write CC 11001100 X X

0 CE 1100111X H L
1 D0 1101000XNCH
2 D2 1101001X H H
3 D4 1101010XNCNC
4 D6 1101011XNC L
5 D8 1101100X L H
6 DA 1101101X HNC
7 DC 1101110X L NC
8 DE 1101111X L L

*H = Tie High; L = Tie to GND; NC = Open; X = Don’t Care

ADDRESS BINARY DEVICE ADDRESS

h a6a5a4a3a2a1a0R/W ADR1 ADR0

LTC4151

ADDRESS PINS

11

4151fb

LTC4151

APPLICATIONS INFORMATION

Table 2. LTC4151 Register Address and Contents

REGISTER ADDRESS* REGISTER NAME READ/WRITE DESCRIPTION

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 V

03h V

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) R/W Controls ADC Operation Mode and Test Mode

07h Reserved

*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

(C) R/W** ADC VIN Voltage Data (8 MSBs)

IN

(D) R/W** ADC VIN Voltage Data (4 LSBs)

IN

Table 4. VIN Registers C (02h) and D (O3h)—Read/Write

BIT NAME OPERATION

C7:0, D7:4 V

D3 ADC Busy in Snapshot Mode 1 = V

D2:0 Reserved Always Returns 0, Not Writable

Voltage Data 12-Bit Data of VIN Voltage with 25mV LSB and 102.4V Full-Scale

IN

Being Converted; 0 = VIN Conversion Completed. Not Writable

IN

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

G5 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

G6 G5 ADC CHANNEL

0 0 SENSE (Default)
01 V
1 0 ADIN

IN

G4 Test Mode Enable Test Mode Halts ADC Operation and Enables Writes to ADC Registers; 1 = Enable Test Mode,

G3 Page Read/Write Enable Enables Page Read/Write; 1 = Enable I2C Page Read/Write (Default), 0 = Disable I2C Page Read/Write

G2 Stuck-Bus Timer Enable Enables I

G1:0 Reserved Always Returns 0, Not Writable

0 = Disable Test Mode (Default)

2

C Stuck-Bus Reset Timer; 1 = Enable Stuck-Bus Timer (Default), 0 = Disable Stuck-Bus Timer

12

4151fb

APPLICATIONS INFORMATION

LTC4151

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.

Layout Considerations

A Kelvin connection between the sense resistor R

and

S

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 stays

R1

V

IN

ADINADIN

ADR1

ADR0

SENSE

LTC4151-2

0.02Ω

+

GND

SENSE

–

SDAO

SDAI

SCL

V

OUT

V

IN

8

IN

LT3010-5

C7

5

1μF

SHDN

100V

SENSE

GND

4

OUT

1

C6
1μF

2

R3

10k

V

7V to 80V

IN

at a reasonable temperature. Using 0.03" per amp or wider
is recommended. Note that 1oz copper exhibits a sheet
resistance of about 530μΩ per square.

V

IN

GND

SENSE

V

IN

ADR1

ADR0

+

R

S

LTC4151

SENSE

GND

–

Figure 10. Recommended Layout for Kelvin Connection

ISO1

R8
1k

R4
10k

PS9817-2

1

2

8

V

CC

7

6

GND

5

ISO2

PS9817-2

V

GND

8

CC

7

5

1

2

3

4

C4

0.1μF

5V

R121kR14

R111kR13

4151 F11

10k

10k

I

LOAD

I

LOAD

4151 F10

ISO_SDA

ISO_SCL

Figure 11. LTC4151-2 I2C Opto-Isolation Interface with High Speed Opto-Couplers

4151fb

13

LTC4151

TYPICAL APPLICATION

Temperature Monitoring with an NTC Thermistor While

Measuring Load Current and LTC4151 Supply Current

V

IN

48V

VISHAY
2381 615 4.104

PACKAGE DESCRIPTION

0.2Ω

100k AT 25
1%

40.2k
1%

1.5k
1%

T(°C) = 58.82 • (N
N

ADIN

ADC AT THE ADIN AND V

AND N

°C

SENSE+SENSE

ADIN

ADIN/NVIN

ARE DIGITAL CODES MEASURED BY THE

VIN

IN

–

LTC4151

GND

– 0.1066), 20°C < T < 60°C.

PINS, RESPECTIVELY.

DD Package

10-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1699 Rev B)

V

IN

SCL

SDA

ADR1

ADR0

4151 TA02

250mA

LOAD

2

I

C

0.70 p0.05

3.55 p0.05

2.15 p0.05

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

1.65 p0.05
(2 SIDES)

PACKAGE
OUTLINE

0.25 p 0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

2.38 p0.05
(2 SIDES)

0.50
BSC

PIN 1

TOP MARK

(SEE NOTE 6)

0.200 REF

14

R = 0.125

TYP

3.00 p0.10
(4 SIDES)

0.75 p0.05

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

1.65 p 0.10
(2 SIDES)

0.00 – 0.05

2.38 p0.10
(2 SIDES)

BOTTOM VIEW—EXPOSED PAD

106

15

0.50 BSC

0.40 p 0.10

(DD) DFN REV B 0309

0.25 p 0.05

4151fb

PACKAGE DESCRIPTION

MS Package

10-Lead Plastic MSOP

(Reference LTC DWG # 05-08-1661 Rev E)

3.00 ± 0.102
(.118 ± .004)

(NOTE 3)

LTC4151

0.497 ± 0.076

7

6

(.0196 ± .003)

REF

8910

5.23

(.206)

MIN

0.305 ± 0.038

(.0120 ± .0015)

TYP

0.889 ± 0.127
(.035 ± .005)

GAUGE PLANE

3.20 – 3.45

(.126 – .136)

0.50

(.0197)

RECOMMENDED SOLDER PAD LAYOUT

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

BSC

0.18

(.007)

0.254
(.010)

DETAIL “A”

0° – 6° TYP

0.53 ± 0.152
(.021 ± .006)

DETAIL “A”

S Package

16-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610)

.050 BSC

N

.045 p.005

16

14

15

SEATING

PLANE

.386 – .394

(9.804 – 10.008)

NOTE 3

13

4.90 ± 0.152

(.193 ± .006)

(.043)

0.17 –0.27

(.007 – .011)

TYP

12

11

1.10

MAX

12

0.50

(.0197)

BSC

10

3

45

9

3.00 ± 0.102

(.118 ± .004)

(NOTE 4)

0.86

(.034)

REF

0.1016 ± 0.0508
(.004 ± .002)

MSOP (MS) 0307 REV E

.245

MIN

.030 p.005

TYP

(0.254 – 0.508)

.008 – .010

(0.203 – 0.254)

.160

p.005

1 2 3 N/2

RECOMMENDED SOLDER PAD LAYOUT

.010 – .020

NOTE:

1. DIMENSIONS IN

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)

s 45o

0o – 8o TYP

.016 – .050

(0.406 – 1.270)

INCHES

(MILLIMETERS)

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 representa­tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

.228 – .244

(5.791 – 6.197)

.053 – .069

(1.346 – 1.752)

(0.355 – 0.483)

N

1

.014 – .019

TYP

.150 – .157

(3.810 – 3.988)

N/2

4

5

.050

(1.270)

BSC

3

2

7

6

NOTE 3

8

.004 – .010

(0.101 – 0.254)

S16 0502

4151fb

15

LTC4151

TYPICAL APPLICATION

High Side Current, Input Voltage and Open Fuse Monitoring

V

IN1

48V

V

IN2

48V

D3

with a Single LTC4151

D1F1

SENSE

RS

0.02Ω

+

SENSE

–

D2F2

D4

GND

R1
150k

R2
301k

R3

3.4k

V

IN

ADIN

LTC4151

GND

SCL

SDA

ADR1

ADR0

I2C

V

LOAD

V

+

–

4151 TA02

CONDITION RESULT

≥ 1.375 • N

N

ADIN

0.835 • N

0.285 • N

VIN

VIN

≤ N

≤ N

VIN

< 1.375 • N

ADIN

< 0.835 • N

ADIN

VIN

VIN

Normal Operation

F2 is Open

F1 is Open

(Not Responding) Both F1 and F2 are Open

AND V

V

IN1

MEASURED BY THE ADC AT THE ADIN AND V

ARE WITHIN 20% APART. N

IN2

AND N

ADIN

PINS, RESPECTIVELY.

IN

ARE DIGITAL CODES

VIN

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LTC2451 16-Bit I2C Ultra Tiny Delta Sigma ADC

LTC2453 16-Bit I

2

C Ultra Tiny Delta Sigma ADC

LTC2970 Power Supply Monitor and Margining Controller 14-Bit ADC Monitoring Current and Voltages, Supplies from 8V to 15V

TM

LTC4215 Positive Hot Swap

Controller with ADC and I2C 8-Bit ADC Monitoring Current and Voltages, Supplies from 2.9V to 15V

LTC4260 Positive High Voltage Hot Swap Controller with

ADC and I2C

LTC4261/
LTC4261-2

LTC6101/
LTC6101HV

Negative High Voltage Hot Swap Controller with
ADC and I2C

High Voltage, High Side Current Sense Amplifi er
in SOT-23 Package

Hot Swap is a trademark of Linear Technology Corporation.

Single-Ended Input, 0 to VCC Input Range, 60Hz Output Rate, 3mm × 2mm
DFN-8 Package

Differential Input, ±VCC Input Range, 60Hz Output Rate, 3mm × 2mm
DFN-8 Package

8-Bit ADC Monitoring Current and Voltages, Supplies from 8.5V to 80V

10-Bit ADC Monitoring Current and Voltages, Supplies from –12V

Supplies from 4V to 60V (LTC6101) and 5V to 100V (LTC6101HV)

16

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear.com

4151fb

LT 0709 REV B • PRINTED IN USA

© LINEAR TECHNOLOGY CORPORATION 2008