LM5056, LM5056A
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SNVS827A – OCTOBER 2012 – REVISED APRIL 2013
High-Voltage System Power Management Device with PMBus™
Check for Samples: LM5056, LM5056A
FEATURES
APPLICATIONS
•
•
•
•
•
1
2
•
•
•
•
•
•
•
•
•
Input Voltage Range: 10 V to 80 V
Real-Time Monitoring of VIN, IIN, PIN, VOUT,
and VAUX with 12-bit resolution, 1-kHz
sampling rate
True input Power Measurement using
simultaneous sampling of Vin and Iin
Remote Temperature Sensing with
programmable warning thresholds
Power Measurement Accuracy
– LM5056A: ±1.75%
– LM5056: ±2.25%
Current Measurement Accuracy
– LM5056A: ±1.25%
– LM5056: ±1.5%
Voltage Measurement Accuracy: ±1.0%
Averaging of VIN, IIN, PIN, and VOUT with
Programmable Interval Ranging from 0.001 s
to 4 s
Programmable WARN and FAULT Thresholds
with SMBA Notification
Black-Box Capture of Telemetry
Measurements and Device Status Triggered by
WARN or FAULT Condition
I2C/SMBus Interface and PMBus Compliant
Command Structure
Server Backplane Systems
Base Station Power Distribution Systems
Industrial Telemetry Applications
DESCRIPTION
The LM5056/LM5056A combines high-performance
analog and digital technology with a PMBus™
compliant SMBus™ and I2C interface to accurately
measure the electrical operating conditions of
systems connected to a backplane power bus. The
LM5056/LM5056A continuously supplies real-time
power, voltage, current, temperature and fault data to
the system management host via the SMBus
interface.
The LM5056/LM5056A monitoring block computes
both the real time and average values of subsystem
operating parameters (VIN, IIN, PIN, VOUT) as well
as the peak power. Accurate power averaging is
accomplished by averaging the product of the input
voltage and current. A black-box (telemetry and fault
snapshot) function captures and stores telemetry data
and device status in the event of a warning or a fault.
SPACER
BETWEEN
APPLICATION DIAGRAM
2
COLUMN
AND
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PMBus is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2012–2013, Texas Instruments Incorporated
LM5056, LM5056A
SNVS827A – OCTOBER 2012 – REVISED APRIL 2013
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TYPICAL APPLICATION DIAGRAM
LOAD
RS
+48V
VOUT
VIN
VIN
VIN_K
SENSE
OUT
VAUX
NC
ADR2
NC
ADR1
NC
ADR0
DIODE
LM5056/LM5056A
MMBT3904
VREF
CVREF
SMBA
SMBus
Interface
SDAI
CL
SDAO
SCL
VDD
DGND
5.0V
AGND
CVDD
2
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SNVS827A – OCTOBER 2012 – REVISED APRIL 2013
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
VALUE
UNIT
VIN, VIN_K, SENSE, OUT to AGND/DGND
-0.3 to 100
SMBA, SCL, SDAI, SDAO, CL, ADR0, ADR1, ADR2, VDD, VAUX, DIODE to AGND/DGND
-0.3 to 6.0
VIN to VIN_K, AGND to DGND
-0.3 to 0.3
VIN_K to SENSE
-3.0 to 3.0
HBM
Human body model ESD rating (2)
TSTG
Storage temperature
-65 to 150
TJ
Junction temperature
150
(1)
(2)
V
2.0
kV
°C
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions for
which the device is intended to be functional, but do not ensure specific performance limits. For ensured specifications and conditions
see Electrical Characteristics Table.
The human body model is a 100-pF capacitor discharged through a 1.5-kΩ resistor into each pin.
RECOMMENDED OPERATING CONDITIONS
over operating free-air temperature range (unless otherwise noted) (1)
MIN
VIN, VIN_K,SENSE, OUT
10
VDD
4.5
VAUX
(1)
NOM
MAX
5.0
5.5
UNIT
80
0
V
2.97
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings indicate conditions for
which the device is intended to be functional, but do not ensure specific performance limits. For ensured specifications and conditions
see the Electrical Characteristics Table.
THERMAL INFORMATION
LM5056
THERMAL METRIC (1)
PWP
UNITS
28 PINS
θJA
Junction-to-ambient thermal resistance (2)
35.6
θJCtop
Junction-to-case (top) thermal resistance (3)
19.9
(4)
θJB
Junction-to-board thermal resistance
ψJT
Junction-to-top characterization parameter (5)
0.5
ψJB
Junction-to-board characterization parameter (6)
16.7
θJCbot
Junction-to-case (bottom) thermal resistance (7)
2.9
(1)
(2)
(3)
(4)
(5)
(6)
(7)
16.8
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
The junction-to-ambient thermal resistance under natural convection is obtained in a simulation on a JEDEC-standard, high-K board, as
specified in JESD51-7, in an environment described in JESD51-2a.
The junction-to-case (top) thermal resistance is obtained by simulating a cold plate test on the package top. No specific JEDECstandard test exists, but a close description can be found in the ANSI SEMI standard G30-88.
The junction-to-board thermal resistance is obtained by simulating in an environment with a ring cold plate fixture to control the PCB
temperature, as described in JESD51-8.
The junction-to-top characterization parameter, ψJT, estimates the junction temperature of a device in a real system and is extracted
from the simulation data for obtaining θJA, using a procedure described in JESD51-2a (sections 6 and 7).
The junction-to-board characterization parameter, ψJB, estimates the junction temperature of a device in a real system and is extracted
from the simulation data for obtaining θJA , using a procedure described in JESD51-2a (sections 6 and 7).
The junction-to-case (bottom) thermal resistance is obtained by simulating a cold plate test on the exposed (power) pad. No specific
JEDEC standard test exists, but a close description can be found in the ANSI SEMI standard G30-88.
Spacer
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ELECTRICAL CHARACTERISTICS
Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature (TJ) range of -40°C
to 125°C unless otherwise stated. Minimum and maximum limits are ensured through test, design, or statistical correlation.
Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless
otherwise stated the following conditions apply: VIN = 48 V and VDD = 5.0 V. See (1) and (2).
PARAMETER
TEST CONDITIONS
MIN
TYP MAX
UNIT
Input (VIN Pin)
IVIN
VIN input current
POREN
Power on reset threshold at VIN to enable
VIN increasing
all functions
POREN_HY
S
VIN = 48 V
POREN hysteresis
7.5
VIN decreasing
0.9
1.4
mA
8.7
9.7
V
150
mV
VDD Regulator (VDD pin)
VDDPOR
VDD power on reset voltage threshold
VDD rising
3.8
4.5
V
IDD
VDD pin input current
VDD = 5.5 V
3.0
6.1
6.8
mA
90
OUT, SENSE, VIN_K, VAUX Pins
IOUT
OUT bias current
OUT = VIN, normal operation
79
ISENSE
SENSE bias current
SENSE = VIN, normal operation
11
IVIN_K
VIN_K bias current
VIN_K = VIN, normal operation
110
IVAUX
VAUXH bias current
VAUX = 2.97 V
μA
1.0
Internal Reference
VREF
Reference voltage
IREF = 0 mA
2.94
2.97
3.0
V
ADC and MUX
ADCRES
Resolution
INL
Integral non-linearity
ADC only
12
bits
±4
LSB
tRR
Acquisition round-robin time
Cycle all channels
1
ms
TA = 25°C to 85°C
2
°C
9
bits
Remote Diode Temperature Sensor
TACC
Temperature accuracy using local diode
Remote diode resolution
IDIODE
External diode current source
DRATIO
Diode current ratio
(1)
(2)
4
High level
250
Low level
9.4
μA
25.9
Current out of a pin is indicated as a negative value.
All limits are ensured. All electrical characteristics having room temperature limits are tested during production at TA = 25°C. All hot and
cold limits are ensured by correlating the electrical characteristics to process and temperature variations and applying statistical process
control.
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ELECTRICAL CHARACTERISTICS (continued)
Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature (TJ) range of -40°C
to 125°C unless otherwise stated. Minimum and maximum limits are ensured through test, design, or statistical correlation.
Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless
otherwise stated the following conditions apply: VIN = 48 V and VDD = 5.0 V. See (1) and(2).
PARAMETER
TEST CONDITIONS
MIN
TYP MAX
UNIT
Telemetry Accuracy
IINFSR
Current input full scale range
IINLSB
Current input LSB
CL = GND
54.4
CL = VDD
27.0
CL = GND
13.3
0
CL = VDD
6.70
μV
2.96
6
V
VAUX input LSB
724
μV
Input voltage full scale range
88.9
V
21.7
mV
VAUXFSR
VAUX input full scale range
VAUXLSB
VINFSR
VINLSB
Input voltage LSB
VIN_K – SENSE_K = 22 mV,
CL = VDD (80% IINFSR),
TJ = 0°C to 85°C
IINACC
mV
-1.5
1.5
%
-1.25
1.25
%
VIN_K – SENSE_K = 5.5 mV,
CL = VDD (20% IINFSR), TJ = 0°C to 85°C
-5.5
5.5
%
VIN_K – SENSE_K = 44 mV,
CL = GND (80% IINFSR), TJ = 0°C to 85°C
-3.5
3.5
%
VIN_K – SENSE_K = 22 mV,
CL = VDD (80% IINFSR), LM5056A
TJ = 0°C to 85°C
Input current accuracy
VIN
VIN accuracy
VIN = 48 V, TJ = 0°C to 85°C
-1
1
%
VOUT
VOUT accuracy
VOUT = 48 V, TJ = 0°C to 85°C
-1
1
%
VAUX
VAUX accuracy
VAUX = 2.8 V, TJ = 0°C to 85°C
-1.3
1.3
%
VIN = 48 V,
VIN_K – SENSE_K = 22 mV,
CL = VDD, TJ = 0°C to 85°C
-2.25
2.25
%
VIN = 48 V,
VIN_K – SENSE_K = 22 mV, LM5056A
CL = VDD, TJ = 0°C to 85°C
-1.75
1.75
%
-3.6
3.6
%
PINACC
Input power accuracy
VIN = 48 V,
VIN_K – SENSE_K = 44 mV,
CL = GND, TJ = 0°C to 85°C
PMBus Pin Thresholds (SMBA, SDAI, SDAO, SCL)
VIL
SDAI, SCL input low voltage
0.9
VIH
SDAI, SCL input high voltage
VOL
SDAO output low voltage
ISINK = 3 mA
ILEAK
Input leakage current
SDAI, SMBA, SCL = 5 V
2.1
V
0.4
1
μA
CL Pin
VIH
Threshold voltage
ILEAK
Input leakage current
3
CL = 5 V
V
10
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5
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TYPICAL CHARACTERISTICS
Unless otherwise specified the following conditions apply: TJ = 25°C, VIN, VIN_K, SENSE, and OUT = 48 V and VDD = 5.0 V.
All graphs show junction temperature.
6.5
6.25
1100
VDD Quiescent Current (mA)
VIN Quiescent Current (µA)
1200
VIN = 80V
1000
900
800
VIN = 48V
700
600
VIN = 9V
500
6
VDD = 5.5V
5.75
5.5
5.25
5
VDD = 5.0V
4.75
4.5
VDD = 4.5V
4.25
400
4
-50
-25
0
25
50
75
100 125 150
±50 ±25
-XQFWLRQ 7HPSHUDWXUH Û&
0
25 50 75 100 125 150
-XQFWLRQ 7HPSHUDWXUH Û&
C010
C001
Figure 1. VIN Pin Current
Figure 2. VDD Quiescent Current
11.50
SENSE Pin Bias Current (µA)
VIN_K Bias Current (µA)
114
112
110
108
106
104
11.45
11.40
11.35
11.30
11.25
11.20
11.15
11.10
11.05
102
±50 ±25
±50 ±25
0
25 50 75 100 125 150
-XQFWLRQ 7HPSHUDWXUH Û&
0
25
50
75
-XQFWLRQ 7HPSHUDWXUH
100 125 150
Û&
C002
C009
Figure 4. SENSE Pin Current
79.1
100
79.05
50
79
VAUX Bias Current (nA)
OUT Bias Current (µA)
Figure 3. VIN_K Pin Current
78.95
78.9
78.85
78.8
78.75
78.7
0
-50
-100
-150
-200
-250
78.65
78.6
-300
-50
-25
0
25
50
75
100 125 150
-50
-XQFWLRQ 7HPSHUDWXUH Û&
6
0
25
50
75
100 125 150
-XQFWLRQ 7HPSHUDWXUH Û&
C011
Figure 5. OUT Pin Current
-25
C012
Figure 6. VAUX Pin Current (VAUX = 2.97 V)
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TYPICAL CHARACTERISTICS (continued)
Unless otherwise specified the following conditions apply: TJ = 25°C, VIN, VIN_K, SENSE, and OUT = 48 V and VDD = 5.0 V.
All graphs show junction temperature.
2.973
0.10
0.08
0.06
2.971
0.04
VIN Error (%)
Reference Voltage (V)
2.972
2.970
2.969
0.02
0.00
±0.02
±0.04
2.968
±0.06
2.967
±0.08
2.966
±0.10
±50 ±25
0
25
50
75
100 125 150
-50
-25
-XQFWLRQ 7HPSHUDWXUH Û&
0
25
50
75
100 125 150
-XQFWLRQ 7HPSHUDWXUH Û&
C008
C005
Figure 7. VREF Voltage
Figure 8. VIN Measurement Error
0.25
0.10
0.20
0.15
POWER Error (%)
Input Current Error (%)
0.05
0.00
±0.05
±0.10
0.10
0.05
0.00
±0.05
±0.10
±0.15
±0.15
±0.20
±0.25
±0.20
±50 ±25
0
25
50
75
-50
100 125 150
-25
0
25
50
75
100 125 150
-XQFWLRQ 7HPSHUDWXUH Û&
-XQFWLRQ 7HPSHUDWXUH Û&
C006
C007
Figure 10. PIN Measurement Error
(VIN_K - SENSE = 22 mV)
0.10
0.10
0.08
0.08
0.06
0.06
0.04
0.04
VAUX Error (%)
VOUT Error (%)
Figure 9. IIN Measurement Accuracy
(VIN_K - SENSE = 22 mV)
0.02
0.00
±0.02
±0.04
0.02
0.00
±0.02
±0.04
±0.06
±0.06
±0.08
±0.08
±0.10
±0.10
-50
-25
0
25
50
75
100 125 150
-50
-XQFWLRQ 7HPSHUDWXUH Û&
-25
0
25
50
75
100 125 150
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C004
Figure 11. VOUT Measurement Error
C003
Figure 12. VAUX Measurment Error (VAUX = 2.80 V)
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DEVICE INFORMATION
HTSSOP Package
28 Pin
(Top View)
OUT
1
28
NC
NC
2
27
NC
SENSE
3
26
NC
VIN_K
4
25
NC
VIN
5
24
NC
23
NC
Exposed
Pad
NC
6
NC
7
22
CL
NC
8
21
VDD
AGND
9
20
ADR0
DGND
10
19
ADR1
SDAI
11
18
ADR2
SDAO
12
17
VAUX
SCL
13
16
DIODE
SMBA
14
15
VREF
TERMINAL FUNCTIONS
TERMINAL
NAME
NO.
Exposed Pad
Pad
I/O
DESCRIPTION
Exposed pad of HTSSOP package. Solder to the ground plane to reduce thermal resistance.
OUT
1
I
Output voltage telemetry input. The OUT pin is an auxiliary high-voltage input to the ADC. Use this
pin to measure the output voltage or other system voltages up to 80 V.
NC
2
-
No connect. Not bonded to the die. Can be connected to the ground plane.
SENSE
3
I
Negative input to the current sense amplifier. The voltage across the current sense resistor (RS) is
measured from VIN_K to SENSE.
VIN_K
4
I
Positive input to the current sense amplifier. The voltage across the current sense resistor (RS) is
measured from VIN_K to SENSE.
VIN
5
I
Positive supply input. VIN is the input supply connection for the device. The input voltage is
measured between this pin and AGND. A small bypass capacitor can be connected from VIN to
AGND/DGND in noisy environments.
NC
6
-
No connect. Not bonded to the die. Connect to the ground plane.
NC
7
-
No connect. Not bonded to the die. Connect to the ground plane.
NC
8
-
No connect. Not bonded to the die. Connect to the ground plane.
AGND
9
-
Analog ground. Connect analog ground to digital ground and then to a quiet system ground. Be sure
to avoid high current return paths.
DGND
10
-
Digital ground. Connect analog ground to digital ground and then to a clean system ground. Be sure
to avoid high current return paths.
SDAI
11
I
SMBus data input. Data input pin for SMBus. Connect to SDAO if the application does not require
unidirectional isolation devices.
SDAO
12
O
SMBus data output. Data output pin for SMBus. Connect to SDAI if the application does not require
unidirectional isolation devices.
SCL
13
I
SMBus clock input. Clock pin for SMBus.
SMBA
14
O
SMBus alert line. Alert pin for SMBus, active low.
VREF
15
O
Internal voltage reference. Internally generated precision 2.97V voltage reference used for analog to
digital conversion. Connect a 1 μF capacitor from this pin to AGND for bypassing.
DIODE
16
O
External temperature diode pin. Connect DIODE to a diode-configured MMBT3904 NPN transistor
for temperature monitoring. The diode return path should be closley coupled with AGND. A small
bypass capacitance on the order of 1 nF is recommended for extra noise immunity.
VAUX
17
I
Auxiliary low voltage input. The Auxiliary pin allows voltage telemetry from an external source. Full
scale input of 2.966 V.
ADR2
18
I
SMBUS address line 2. Tri-state address line. Should be connected to DGND, VDD, or left floating.
8
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TERMINAL FUNCTIONS (continued)
TERMINAL
I/O
DESCRIPTION
19
I
SMBUS address line 1. Tri-state address line. Should be connected to DGND, VDD, or left floating.
20
I
SMBUS address line 0. Tri-state address line. Should be connected to DGND, VDD, or left floating.
VDD
21
I
VDD input to internal digital circuitry. Provide a 5.0-V (±10% allowable) voltage supply to VDD to
power the internal digital circuitry. Connect a 1 μF capacitor on this pin to AGND for bypassing.
CL
22
O
Current range select pin. Connecting this pin to VDD or DGND selects between a full-scale current
sense voltage range of 27.0 mV and 54.4 mV respectively.
NC
23
-
Bonded to die for testing purposes. Connect to the ground plane.
NC
24
-
Bonded to die for testing purposes. Connect to the ground plane.
NC
25
-
No connect. Not bonded to the die. Connect to the ground plane.
NC
26
-
No connect. Not bonded to the die. Connect to the ground plane.
NC
27
-
No connect. Not bonded to the die. Connect to the ground plane.
NC
28
-
No connect. Not bonded to the die. Connect to the ground plane.
NAME
NO.
ADR1
ADR0
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FUNCTIONAL BLOCK DIAGRAM
VDD
5.0V
DIGITAL
LM5056/LM5056A
0V to 80V
ANALOG
OUT
VIN
SENSE
VIN_K
10V to 80V
MEASUREMENT/
AVERAGING/
WARN/
REGISTERS
VREF
2.97 V
REF
VAUX
DIODE
S/ H
12 bit
ADC
AMUX
1/30
SCL
SDAI
1/30
TELEMETRY
STATE
MACHINE
SMBUS
INTERFACE
SDAO
SMBA
0V ± 2.966V
ADDRESS
DECODER
DIODE
TEMP
SENSE
ADR0
CL
ADR1
Cl = VDD, CURRENT SENSE FSR = 27.0 mV
Cl = GND, CURRENT SENSE FSR = 54.4 mV
ADR2
AGND
10
DGND
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FUNCTIONAL DESCRIPTION
The LM5056/LM5056A provides intelligent monitoring of the input voltage, output voltage, input current, input
power, temperature, and an auxiliary input. The LM5056/LM5056A also provides a peak capture of the input
power and programmable hardware averaging of the input voltage, current, power, temperature, and output
voltage. Warning thresholds which trigger the SMBA pin may be programmed for input voltage, current, power,
output voltage, and temperature via the PMBus interface.
Powering The LM5056/LM5056A
The LM5056/LM5056A is enabled by increasing the input voltage on VIN above the POREN threshold voltage,
typically 8.7 V. There exists a VDD power on reset (VDDPOR) threshold on VDD of 3.8 V. The VDDPOR threshold
must be surpassed to ensure proper telemetry readings. VDD must be powered externally by a 5 V power supply
with an allowable tolerance of ±10%.The SMBus address of the LM5056/LM5056A is captured based on the
states of the ADR0, ADR1, and ADR2 pins (GND, NC, VDD) during turn on and is latched into a volatile register
once VDD has exceeded its POR threshold of 3.8 V. Reassigning or postponing the address capture is
accomplished by holding the VREF pin to AGND. Pulling the VREF pin low also resets the logic and erases the
volatile memory of the LM5056/LM5056A. Once released, the VREF pin charges up to its final value and the
address is latched into a volatile register when the voltage at the VREF exceeds 2.55 V.
VDD
As mentioned in the previous paragraph, the LM5056/LM5056A VDD pin must be externally powered by a 5.0 V,
±10% supply. The required current is typically 6.1 mA. The pull-up voltage for the CL, ADR2, ADR1 and ADR0
pins should be the same as the voltage applied to VDD if they are to be tied high. It may also be used as the
pull-up supply for the SMBus signals (SDAI/O, SCL, SMBA). It is recommended to connect a ceramic bypass
capacitance having a value of 1 μF or greater as close to the VDD pin as the PCB layout allows.
Remote Temperature Sensing
The LM5056/LM5056A is designed to measure temperature remotely using an MMBT3904 NPN transistor. The
base and collector of the MMBT3904 should be connected to the DIODE pin and the emitter to the
LM5056/LM5056A AGND. Place the MMBT3904 near the device that requires temperature sensing. The
temperature is measured by means of a change in the diode voltage in response to a step in current supplied by
the DIODE pin. The DIODE pin sources a constant 9.4 µA but pulses 250 µA once every millisecond in order to
measure the diode temperature. Care must be taken in the PCB layout to keep the parasitic resistance between
the DIODE pin and the MMBT3904 low as to not degrade the measurement. Additionally, a small 1 nF bypass
capacitor should be placed in parallel with the MMBT3904 to reduce the effects of noise. The temperature can be
read using the READ_TEMPERATURE_1 PMBus command (8Dh). The default limits of the LM5056/LM5056A
causes SMBA pin to be pulled low if the measured temperature exceeds 150°C. These thresholds can be
reprogrammed via the PMBus interface using the OT_WARN_LIMIT (51h) and OT_FAULT_LIMIT (4Fh)
commands. If the temperature measurement and protection capability of the LM5056/LM5056A are not used, the
DIODE pin should be connected to the ground plane.
Erroneous temperature measurements may result when the device input voltage is below the minimum operating
voltage (10 V), due to VREF dropping out below the nominal voltage (2.97 V).
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APPLICATION INFORMATION
DESIGN-IN PROCEDURE
Refer to Figure 13 for the Typical Application Circuit diagram. The following is the step-by-step procedure for
hardware design of the LM5056/LM5056A. This procedure refers to section numbers that provide detailed
information on the following design steps. The recommended design-in procedure is as follows:
LOAD
RS
+48V
VOUT
VIN
CS
CVIN
VIN
VIN_K
SENSE
OUT
VAUX
NC
ADR2
NC
ADR1
NC
ADR0
DIODE
LM5056/
LM5056A
VREF
MMBT3904
CVREF
SMBA
SMBus
Interface
CD
SDAI
CL
SDAO
VDD
SCL
DGND
5.0V
AGND
CVDD
Figure 13. Typical Application Circuit
CURRENT Range (Selecting RS)
The LM5056/LM5056A monitors the input current by measuring the voltage across the sense resistor (RS),
connected from VIN_K to SENSE. The required resistor value is calculated from:
V
RS= I S
FS
where
•
IFS is the expected full scale current and VS is the current sense voltage range based on the current select
range setting (CL).
(1)
If the voltage across RS reaches VS, the current measurement reaches the full-scale measurement. As
mentioned before, it is important to limit the current to the full-scale reading. While there is internal circuitry
intended to maintain the integrity of the other readings in the telemetry, the ADC and MUX are shared so
overranging an input may compromise the integrity of the other readings.
VS can be set to either 27.0 mV or 54.4 mV through software commands or the CL pin. This setting defaults to
the sense voltage set at the CL pin during start-up. The value can be set via the PMBus with the
DEVICE_SETUP (D9h) command, which defaults to the 27.0 mV setting. Once the full scale current, IFS is known
and the VS range is chosen, the sense resistor can be calculated. The maximum load current in normal operation
can be used to determine the required power rating for the sense resistor RS.
Connections from RS to the LM5056/LM5056A should be made using Kelvin techniques. In the suggested layout
of Figure 14 the small pads at the lower corners of the sense resistor connect only to the sense resistor
terminals, and not to the traces carrying the high current. With this technique, only the voltage across the sense
resistor is applied to VIN_K and SENSE, eliminating the voltage drop across the high-current solder connections.
12
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HIGH CURRENT PATH
FROM SYSTEM
INPUT VOLTAGE
SENSE
RESISTOR
TO LOAD
RS
VIN
VIN_K
SENSE
Figure 14. Sense Resistor Connections, Edge Sensed
If the PCB layout and resistor pads allow for it, the connection shown in Figure 15 gives optimal kelvin sensing
performance.
HIGH CURRENT PATH
SENSE
RESISTOR
FROM SYSTEM
INPUT VOLTAGE
VIN
RS
VIN_K
TO LOAD
SENSE
Figure 15. Sense Resistor Connections, Centered Sensed
CVIN, CD, CVREF, CS, and CVDD
Using ceramic bypass capacitors can improve performance in noise heavy environments. Not every pin of the
LM5056/LM5056A is the same when it comes to placing bypass capacitors.
• CVIN: This capacitor is not required but can improve VIN telemetry performance in noisy situations. Typical
values for the VIN bypass capacitor can range from 1 nF to 100 nF to effectivly reduce input noise. The
voltage on CVIN is high, so a 100 V or higher voltage capacitor will work.
• CD:The CD capacitor is recommended if the diode is placed far from the LM5056/LM5056A DIODE pin. Too
large of a capacitance will corrupt the voltage waveform across the diode used to measure the absolute
temperature. A typical value of capacitance for CD is 1 nF. The voltage on CD is low, so a 6.3 V or higher
voltage capacitor will work.
• CVREF: CVREF is required since it is placed on the output of the internal votlage reference. This capacitor
should be a 1 μF ceramic. The voltage on CVREF is low, so a 6.3 V or higher voltage capacitor will work.
• CS: The current sense amplifier is designed to amplifiy small voltages. Using a bypass capacitor across the
current sense amplifier input pins (VIN_K and SENSE) will facilitate accurate current telemetry. Functional
values of CS can range from 10 nF to 1 μF. The voltage on CS is low, so a 6.3 V or higher voltage capacitor
will work.
• CVDD: CVDD is required because it provides bypassing from the 5.0 V rail for the internal digital circuitry. This
capacitor should be a 1-μF ceramic. The voltage on CVDD is low, so a 6.3 V or higher voltage capacitor will
work.
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PC Board Guidelines
The following guidelines should be followed when designing the PC board for the LM5056/LM5056A:
• Place a 1-μF ceramic capacitor as close as possible to VREF pin and AGND.
• Place a 1-μF ceramic capacitor as close as possible to VDD pin and AGND.
• Minimize the inductance between the VIN and VIN_K pins. There are anti-parallel diodes between these pins
so any voltage greater than 0.3 V in either polarity causes significant current flow through the diodes, which
can result in device failure. Do not place any resistors between these two nodes.
• Minimize the voltage between the VIN_K and SENSE pins. There are anti-parallel diodes between these pins
so any voltage greater than 3.0 V in either polarity causes significant current flow through the diodes. Internal
series resistors limit the current in these pins and provide a limited level of protection in the event of a voltage
transient.
• The sense resistor (RS) should be placed close to the LM5056/LM5056A. Connect RS using the Kelvin
techniques shown in Figure 14 or Figure 15.
• The high-current path from the board’s input to the load and the return path, should be parallel and close to
each other to minimize loop inductance.
• The AGND and DGND connections should be connected at the pins of the device. The return connections for
the various components around the LM5056/LM5056A should be connected directly to each other, and to the
LM5056/LM5056A’s DGND and AGND pin connections, and then connected to the system ground at one
point. Do not connect the various component return pads to each other through the high current ground line.
14
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PGND
Primary power
supply
Voltage
output
SCL
SDAO
SDAI
SMBA
ADR0
SMBus
Interface
ADR1
NC
ADR2
NC
VDD
CIN
VIN
SENSE
DGND
AGND
LM5056/
LM5056A
VIN_K
RS
OUT
VDD
CL
VREF
VAUX
DIODE
CVDD
CVREF
Sense Luminosity
LED Fault
+5.0V
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B
A
RTHM2
RTHM1
CVCC
AGND
RFB2
RDHC
CFLT
CTHM
RDMIN2
RDMIN1
CDHC
GD4
SE4
GD3
SE3
GD2
SE2
GD1
SE1
DR1
DR2
DR3
DR4
VIN
AGND
AGND
PGND
PGND
Thermal_Cap
DMIN
SYNC
LM5056/
LM5056A
Thermal
VCC
Faultb
DIM
VDHC
FAULT_CAP
EN
OutP
VLedFB
CDHC
Q4
PGND
RISNS4
Q3
PGND
RISNS3
Q2
PGND
RISNS2
PGND
RISNS1
Q1
NTC thermistor
couple to LED
arrays
Luminosity
Sensor
B
A
To thermal
sensor
terminals
www.ti.com
To NTC thermal
sensor
IN
OUT
TPS71401
GND
RP
VDD
Voltage
feedback pin
of PSU
RFB1
MMBT3904
Temperature Sensor
High Power LED Arrays
LM5056, LM5056A
SNVS827A – OCTOBER 2012 – REVISED APRIL 2013
Applications Circuit
Power, voltage, current, fault, temperature, and LED luminosity telemetry for LED street lamps.
Figure 16. LED Street Lamp Telemetry
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15
16
SMBus
Interface
ADR0
NC
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SCL
SDAO
SDAI
SMBA
ADR1
ADR2
NC
VDD
CIN
VIN
SENSE
DGND
AGND
LM5056/
LM5056A
VIN_K
RS
OUT
VDD
CL
VREF
VAUX
DIODE
VIN
CVDD
+5.0V System Bias
CVREF
AUXILIARY
TELEMETRY 1
SMBus
Interface
POWER
STAGE
TEMP
SENSE
AMBIENT/CHASSIS
TEMP SENSE
TPS40170
MMBT3904
+48V
VAUX
VS-
LM5056/
LM5056A
VS+
VREF
SMBA
+5.0V System
SDA
Bias Telemetry
SCL
VDD
DGND
AGND ADR 0/1/2
DIODE
VIN
CVDD
CVREF
AUXILIARY
TELEMETRY 2
+5.0V System Bias
+48V
LM5056, LM5056A
SNVS827A – OCTOBER 2012 – REVISED APRIL 2013
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Applications Circuit
Telemetry of input rail and 5-V bias rail output current and voltage.
Figure 17. 48-V Input Rail and 5-V Bias Rail Telemetry
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SNVS827A – OCTOBER 2012 – REVISED APRIL 2013
PMBus™ Command Support
The device features an SMBus interface that allows the use of PMBus commands to set warn levels, error
masks, and get telemetry on VIN, VOUT, IIN, VAUX, and PIN. The supported PMBus commands are shown in
Table 1.
Table 1. PMBus™ Command Support
CODE
NAME
03h
CLEAR_FAULTS
19h
CAPABILITY
FUNCTION
Clears the status registers and re-arms the black box
registers for updating.
Retrieves the device capability.
R/W
NUMBER
OF DATA
BYTES
Send Byte
0
DEFAULT
VALUE
R
1
B0h
Retrieves or stores output under-voltage, warn-limit
threshold.
R and W
2
0000h
43h
VOUT_UV_WARN_LIMIT
4Fh
OT_FAULT_LIMIT
Retrieves or stores over-temperature, fault-limit
threshold.
R and W
2
0960h
(150°C)
51h
OT_WARN_LIMIT
Retrieves or stores over-temperature, warn-limit
threshold.
R and W
2
07D0h
(125°C)
57h
VIN_OV_WARN_LIMIT
Retrieves or stores input over-voltage, warn-limit
threshold.
R and W
2
0FFFh
58h
VIN_UV_WARN_LIMIT
Retrieves or stores input under-voltage, warn-limit
threshold.
R and W
2
0000h
78h
STATUS_BYTE
Retrieves information about the parts operating status.
R
1
01h
79h
STATUS_WORD
Retrieves information about the parts operating status.
R
2
1801h
7Ah
STATUS_VOUT
Retrieves information about output voltage status.
R
1
00h
7Ch
STATUS_INPUT
Retrieves information about input status.
R
1
00h
7Dh
STATUS_TEMPERATURE
Retrieves information about temperature status.
R
1
00h
7Eh
STATUS_CML
Retrieves information about communications status.
R
1
00h
80h
STATUS_MFR_SPECIFIC
Retrieves information about default status.
R
1
10h
88h
READ_VIN
Retrieves input voltage measurement.
R
2
0000h
8Bh
READ_VOUT
Retrieves output voltage measurement.
R
2
0000h
8Dh
READ_TEMPERATURE_1
Retrieves temperature measurement.
R
2
0190h
99h
MFR_ID
Retrieves manufacturer ID in ASCII characters (NSC).
R
3
4Eh
53h
43h
Retrieves Part number in ASCII characters.
(LM5056/LM5056A/LM5056/LM5056AA).
R
8
4Ch
4Dh
35h
30h
35h
36h
00h
00h
Retrieves part revision letter and number in ASCII
(e.g., AA).
R
2
41h
41h
MFR_SPECIFIC_00
MFR_READ_VAUX
Retrieves auxiliary voltage measurement.
R
2
0000h
D1h
MFR_SPECIFIC_01
MFR_READ_IIN
Retrieves input current measurement.
R
2
0000h
D2h
MFR_SPECIFIC_02
MFR_READ_PIN
Retrieves input power measurement.
R
2
0000h
D3h
MFR_SPECIFIC_03
MFR_IIN_OC_WARN_LIMIT
Retrieves or stores input-current-limit warn threshold.
R and W
2
0FFFh
D4h
MFR_SPECIFIC_04
MFR_PIN_OP_WARN_LIMIT
Retrieves or stores input-power-limit warn threshold.
R and W
2
0FFFh
D5h
MFR_SPECIFIC_05
MFR_READ_PIN_PEAK
Retrieves measured peak-input-power measurement.
R
2
0000h
9Ah
MFR_MODEL
9Bh
MFR_REVISION
D0h
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Table 1. PMBus™ Command Support (continued)
CODE
NAME
FUNCTION
R/W
NUMBER
OF DATA
BYTES
D6h
MFR_SPECIFIC_06
MFR_CLEAR_PIN_PEAK
Resets the contents of the peak-input-power register to
zero.
Send Byte
0
D8h
MFR_SPECIFIC_08
MFR_ALERT_MASK
Retrieves or stores user SMBA fault mask.
R and W
2
0800h
D9h
MFR_SPECIFIC_09
MFR_DEVICE_SETUP
Retrieves or stores information about current sense
gain setting.
R and W
1
0000h
R
12
0880h
0000h
0000h
0000h
0000h
0000h
R and W
1
00h
Retrieves averaged input-voltage measurement.
R
2
0000h
Retrieves averaged output-voltage measurement.
R
2
0000h
DAh
MFR_SPECIFIC_10
MFR_BLOCK_READ
DBh
MFR_SPECIFIC_11
MFR_SAMPLES_FOR_AVG
DCh
MFR_SPECIFIC_12
MFR_READ_AVG_VIN
DDh
MFR_SPECIFIC_13
MFR_READ_AVG_VOUT
DEh
MFR_SPECIFIC_14
MFR_READ_AVG_IIN
Retrieves averaged input-current measurement.
R
2
0000h
DFh
MFR_SPECIFIC_15
MFR_READ_AVG_PIN
Retrieves averaged input-power measurement.
R
2
0000h
Exponent value AVGN for number of samples to be
averaged (N = 2AVGN), range = 00h to 0Ch .
E0h
MFR_SPECIFIC_16
MFR_BLACK_BOX_READ
Captures diagnostic and telemetry information which
are latched when the first SMBA event after faults are
cleared.
E1h
MFR_SPECIFIC_17
MFR_DIAGNOSTIC_WORD_
READ
Manufacturer-specific parallel of the STATUS_WORD
to convey all FAULT and WARN data in a single
transaction.
E2h
18
Retrieves most recent diagnostic and telemetry
information in a single transaction.
DEFAULT
VALUE
MFR_SPECIFIC_18
MFR_AVG_BLOCK_READ
Retrieves most recent average telemetry and
diagnostic information in a single transaction.
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R
12
0000h
0000h
0000h
0000h
0000h
0000h
R
2
0880h
12
0000h
0000h
0000h
0000h
0000h
0000h
R
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Standard PMBus Commands
CLEAR_FAULTS (03h)
The CLEAR_FAULTS command is a standard PMBus command that resets all stored warning and fault flags
and the SMBA signal. If a fault or warning condition still exists when the CLEAR_FAULTS command is issued,
the SMBA signal may not clear or will reassert almost immediately. This command uses the PMBus send byte
protocol.
CAPABILITY (19h)
The CAPABILITY command is a standard PMBus command that returns information about the PMBus functions
supported by the LM5056/LM5056A/LM5056/LM5056AA. This command is read with the PMBus read byte
protocol.
Table 2. CAPABILITY Register
VALUE
MEANING
DEFAULT
B0h
Supports packet error check, 400 Kbits/s, supports SMBus alert
B0h
VOUT_UV_WARN_LIMIT (58h)
The VOUT_UV_WARN_LIMIT command is a standard PMBus command that allows configuring or reading the
threshold for the VOUT under-voltage warning detection. Reading and writing to this register should use the
coefficients shown in the Table 39. Accesses to this command should use the PMBus read or write word
protocol. If the measured value of VOUT falls below the value in this register, VOUT under-voltage warn flags are
set and the SMBA signal is asserted.
Table 3. VOUT_UV_WARN_LIMIT Register
VALUE
MEANING
DEFAULT
0001h – 0FFFh
VOUT under-voltage warning detection threshold
0000h (disabled)
0000h
VOUT under-voltage warning disabled
n/a
OT_FAULT_LIMIT (4Fh)
The OT_FAULT_LIMIT command is a standard PMBus command that allows configuring or reading the threshold
for the over-temperature fault detection. Reading and writing to this register should use the coefficients shown in
the Table 39. Accesses to this command should use the PMBus read or write word protocol. If the measured
temperature exceeds this value, an over-temperature fault is triggered and the SMBA signal is asserted. After the
measured temperature falls below the value in this register, the CLEAR_FAULTS command (03h) should be sent
to de-assert the SMBA signal. A single temperature measurement is an average of 16 round-robin cycles;
therefore, the minimum temperature fault detection time is 16 ms.
Table 4. OT_FAULT_LIMIT Register
VALUE
MEANING
DEFAULT
0000h – 0FFEh
Over-temperature fault threshold value
0960h (150°C)
0FFFh
Over-temperature fault detection disabled
n/a
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OT_WARN_LIMIT (51h)
The OT_WARN_LIMIT command is a standard PMBus command that allows configuring or reading the threshold
for the over-temperature warning detection. Reading and writing to this register should use the coefficients
shown in the Table 39. Accesses to this command should use the PMBus read or write word protocol. If the
measured temperature exceeds this value, an over-temperature warning is triggered and the over-temperature
warn flags set in the respective registers and the SMBA signal asserted. A single temperature measurement is
an average of 16 round-robin cycles; therefore, the minimum temperature warn detection time is 16 ms.
Table 5. OT_WARN_LIMIT Register
VALUE
MEANING
DEFAULT
0000h – 0FFEh
Over-temperature warn threshold value
07D0h (125°C)
0FFFh
Over-temperature warn detection disabled
n/a
VIN_OV_WARN_LIMIT (57h)
The VIN_OV_WARN_LIMIT command is a standard PMBus command that allows configuring or reading the
threshold for the VIN over-voltage warning detection. Reading and writing to this register should use the
coefficients shown in the Table 39 Table. Accesses to this command should use the PMBus read or write word
protocol. If the measured value of VIN rises above the value in this register, VIN over-voltage warn flags are set
in the respective registers and the SMBA signal is asserted.
Table 6. VIN_OV_WARN_LIMIT Register
VALUE
MEANING
DEFAULT
0000h – 0FFEh
VIN Over-voltage warning detection threshold
0FFFh (disabled)
0FFFh
VIN Over-voltage warning disabled
n/a
VIN_UV_WARN_LIMIT (58h)
The VIN_UV_WARN_LIMIT command is a standard PMBus command that allows configuring or reading the
threshold for the VIN under-voltage warning detection. Reading and writing to this register should use the
coefficients shown in the Table 39. Accesses to this command should use the PMBus read or write word
protocol. If the measured value of VIN falls below the value in this register, VIN under-voltage warn flags are set
in the respective register, and the SMBA signal is asserted.
Table 7. VIN_UV_WARN_LIMIT Register
VALUE
MEANING
DEFAULT
0001h – 0FFFh
VIN under-voltage warning detection threshold
0000h (disabled)
0000h
VIN under-voltage warning disabled
n/a
STATUS_BYTE (78h)
The STATUS_BYTE is a standard PMBus command that returns the value of a number of flags indicating the
state of the LM5056/LM5056A. Accesses to this command should use the PMBus read byte protocol. To clear
bits in this register, the underlying fault should be removed on the system and a CLEAR_FAULTS command
issued.
Table 8. STATUS_BYTE Definitions
20
BIT
NAME
MEANING
DEFAULT
7
BUSY
Not supported, always 0
0
6
OFF
Not supported, always 0
0
5
VOUT_OV
Not supported, always 0
0
4
IOUT_OC
Not supported, always 0
0
3
VIN_UV
An input under-voltage fault has occurred
0
2
TEMPERATURE
A temperature fault or warning has occurred
0
1
CML
A communication fault has occurred
0
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Table 8. STATUS_BYTE Definitions (continued)
BIT
NAME
MEANING
DEFAULT
0
None of the above
Not supported, always 1
1
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STATUS_WORD (79h)
The STATUS_WORD command is a standard PMBus command that returns the value of a number of flags
indicating the state of the LM5056/LM5056A. Accesses to this command should use the PMBus read word
protocol. To clear bits in this register, the underlying fault should be removed and a CLEAR _FAULTS command
issued.
Table 9. STATUS_WORD Definitions
BIT
NAME
MEANING
DEFAULT
15
VOUT
An output voltage warning has occurred
0
14
IOUT/POUT
Not supported, always 0
0
13
INPUT
Not supported, always 0
0
12
MFR
A manufacturer specific fault or warning has occurred
1
11
POWER GOOD
Not supported, always 1
1
10
FANS
Not supported, always 0
0
9
OTHER
Not supported, always 0
0
8
UNKNOWN
Not supported, always 0
0
7
BUSY
Not supported, always 0
0
6
OFF
Not supported, always 0
0
5
VOUT OV
Not supported, always 0
0
4
IOUT OC
Not supported, always 0
0
3
VIN UV
Not supported, always 0
0
2
TEMPERATURE
A temperature fault or warning has occurred
0
1
CML
A communication fault has occurred
0
0
None of the above
Not supported, always 1
1
STATUS_VOUT (7Ah)
The STATUS_VOUT command is a standard PMBus command that returns the value of the VOUT under-voltage
warn flag. Accesses to this command should use the PMBus read byte protocol. To clear bits in this register, the
underlying fault should be cleared and a CLEAR_FAULTS command issued.
Table 10. STATUS_VOUT Definitions
BIT
22
NAME
MEANING
DEFAULT
7
VOUT OV fault
Not supported, always 0
0
6
VOUT OV warn
Not supported, always 0
0
5
VOUT UV warn
A VOUT under-voltage warning has occurred
0
4
VOUT UV fault
Not supported, always 0
0
3
VOUT max
Not supported, always 0
0
2
TON max fault
Not supported, always 0
0
1
TOFF max fault
Not supported, always 0
0
0
VOUT tracking error
Not supported, always 0
0
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STATUS_INPUT (7Ch)
The STATUS_INPUT command is a standard PMBus command that returns the value of a number of flags
related to input voltage, current, and power. Accesses to this command should use the PMBus read byte
protocol. To clear bits in this register, the underlying fault should be cleared and a CLEAR_FAULTS command
issued.
Table 11. STATUS_INPUT Definitions
BIT
NAME
MEANING
DEFAULT
7
VIN OV Fault
Not supported, always 0
0
6
VIN OV Warn
A VIN over-voltage warning has occurred
0
5
VIN UV Warn
A VIN under-voltage warning has occurred
0
4
VIN UV Fault
Not supported, always 0
0
3
Insufficient voltage
Not supported, always 0
0
2
IIN OC Fault
Not supported, always 0
0
1
IIN OC Warn
An IIN over-current warning has occurred
0
0
PIN OP Warn
A PIN over-power warning has occurred
0
STATUS_TEMPERATURE (7dh)
The STATUS_TEMPERATURE is a standard PMBus command that returns the value of the of a number of flags
related to the temperature telemetry value. Accesses to this command should use the PMBus read byte protocol.
To clear bits in this register, the underlying fault should be cleared and a CLEAR_FAULTS command issued.
Table 12. STATUS_TEMPERATURE Definitions
BIT
NAME
MEANING
DEFAULT
7
Over-temp fault
An over-temperature fault has occurred
0
6
Over-temp warn
An over-temperature warning has occurred
0
5
Under-temp warn
Not supported, always 0
0
4
Under-temp fault
Not supported, always 0
0
3
reserved
Not supported, always 0
0
2
reserved
Not supported, always 0
0
1
reserved
Not supported, always 0
0
0
reserved
Not supported, always 0
0
STATUS_CML (7Eh)
The STATUS_CML is a standard PMBus command that returns the value of a number of flags related to
communication faults. Accesses to this command should use the PMBus read byte protocol. To clear bits in this
register, a CLEAR_FAULTS command should be issued.
Table 13. STATUS_CML Definitions
BIT
NAME
DEFAULT
7
Invalid or unsupported command received
0
6
Invalid or unsupported data received
0
5
Packet Error Check failed
0
4
Not supported, always 0
0
3
Not supported, always 0
0
2
Not supported, always 0
0
1
Miscellaneous communications fault has occurred
0
0
Not supported, always 0
0
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STATUS_MFR_SPECIFIC (80h)
The STATUS_MFR_SPECIFIC command is a standard PMBus command that contains manufacturer specific
status information. Accesses to this command should use the PMBus read byte protocol. To clear bits in this
register, the underlying fault should be removed and a CLEAR_FAULTS command should be issued.
Table 14. STATUS_MFR_SPECIFIC Definitions
BIT
NAME
DEFAULT
7
Not supported, always 0
0
6
Not supported, always 0
0
5
Not supported, always 0
0
4
Defaults loaded
1
3
Not supported, always 0
0
2
Not supported, always 0
0
1
Not supported, always 0
0
0
Not supported, always 0
0
READ_VIN (88h)
The READ_VIN command is a standard PMBus command that returns the 12-bit measured value of the input
voltage (VIN to AGND). Reading this register should use the coefficients shown in the Table 39. Accesses to this
command should use the PMBus read word protocol. This value is also used internally for the VIN over and
under-voltage warning detection.
Table 15. READ_VIN Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Measured value for VIN
0000h
READ_VOUT (8Bh)
The READ_VOUT command is a standard PMBus command that returns the 12-bit measured value of the output
voltage. Reading this register should use the coefficients shown in the Table 39 Table. Accesses to this
command should use the PMBus read word protocol. This value is also used internally for the VOUT
under_voltage warning detection.
Table 16. READ_VOUT Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Measured value for VOUT
0000h
READ_TEMPERATURE_1 (8Dh)
The READ_TEMPERATURE_1 command is a standard PMBus command that returns the signed value of the
temperature measured by the external temperature sense diode. Reading this register should use the coefficients
shown in the Table 39. Accesses to this command should use the PMBus read word protocol. This value is also
used internally for the over-temperature fault and warning detection. This data has a range of -256°C to 255°C
after the coefficients are applied.
Table 17. READ_TEMPERATURE_1 Register
24
VALUE
MEANING
DEFAULT
0h – 0FFFh
Measured value for TEMPERATURE
0190h
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MFR_ID (99h)
The MFR_ID command is a standard PMBus command that returns the identification of the manufacturer. To
read the MFR_ID, use the PMBus block read protocol.
Table 18. MFR_ID Register
BYTE
NAME
VALUE
0
Number of bytes
03h
1
MFR ID-1
4Eh ‘N’
2
MFR ID-2
53h ‘S’
3
MFR ID-3
43h ‘C’
MFR_MODEL (9Ah)
The MFR_MODEL command is a standard PMBus command that returns the part number of the chip. To read
the MFR_MODEL, use the PMBus block read protocol.
Table 19. MFR_MODEL Register
BYTE
NAME
VALUE
0
Number of bytes
08h
1
MFR ID-1
4Ch ‘L’
2
MFR ID-2
4Dh ‘M’
3
MFR ID-3
35h ‘5’
4
MFR ID-4
30h ‘0’
5
MFR ID-5
35h ‘5’
6
MFR ID-6
36h ‘6’
7
MFR ID-7
00h
8
MFR ID-8
00h
MFR_REVISION (9Bh)
The MFR_REVISION command is a standard PMBus command that returns the revision level of the part. To
read the MFR_REVISION, use the PMBus block read protocol.
Table 20. MFR_REVISION Register
BYTE
NAME
VALUE
0
Number of bytes
02h
1
MFR ID-1
41h ‘A’
2
MFR ID-2
41h ‘A’
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Manufacturer Specific PMBus™ Commands
MFR_SPECIFIC_00: MFR_READ_VAUX (D0h)
The MFR_READ_VAUX command will report the 12-bit ADC measured auxiliary voltage. Voltages greater than
or equal to 2.97 V to ground are reported at plus full scale (0FFFh). Voltages less than or equal to 0 V
referenced to ground are reported as 0 (0000h). To read data from the MFR_READ_VAUX command, use the
PMBus Read Word protocol.
Table 21. MFR_READ_VAUX Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Measured value for VAUX input
0000h
MFR_SPECIFIC_01: MFR_READ_IIN (D1h)
The MFR_READ_IIN command reports the 12-bit ADC measured current sense voltage. To read data from the
MFR_READ_IIN command, use the PMBus Read Word protocol. Reading this register should use the
coefficients shown in the Table 39. Please see the section on coefficient calculations to calculate the values to
use.
Table 22. MFR_READ_IIN Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Measured value for input current sense voltage
0000h
MFR_SPECIFIC_02: MFR_READ_PIN (D2h)
The MFR_READ_PIN command reports the upper 12 bits of the VIN x IIN product as measured by the 12-bit
ADC. To read data from the MFR_READ_PIN command, use the PMBus Read Word protocol. Reading this
register should use the coefficients shown in the Table 39. Please see the section on coefficient calculations to
calculate the values to use.
Table 23. MFR_READ_PIN Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Value for input current x input voltage
0000h
MFR_SPECIFIC_03: MFR_IN_OC_WARN_LIMIT (D3h)
The MFR_IIN_OC_WARN_LIMIT PMBus command sets the input over-current warning threshold. In the event
that the input current rises above the value set in this register, the IIN over-current flags are set in the respective
registers and the SMBA is asserted. To access the MFR_IIN_OC_WARN_LIMIT register, use the PMBus
Read/Write Word protocol. Reading/writing to this register should use the coefficients shown in the Table 39.
Table 24. MFR_IIN_OC_WARN_LIMIT Register
26
VALUE
MEANING
DEFAULT
0h – 0FFEh
Value for input over-current warn limit
0FFFh
0FFFh
Input over-current warning disabled
n/a
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MFR_SPECIFIC_04: MFR_PIN_OP_WARN_LIMIT (D4h)
The MFR_PIN_OP_WARN_LIMIT PMBus command sets the input over-power warning threshold. In the event
that the input power rises above the value set in this register, the PIN over-power flags are set in the respective
registers and the SMBA is asserted. To access the MFR_PIN_OP_WARN_LIMIT register, use the PMBus
Read/Write Word protocol. Reading/writing to this register should use the coefficients shown in the Table 39.
Table 25. MFR_PIN_OPWARN_LIMIT Register
VALUE
MEANING
DEFAULT
0h – 0FFEh
Value for input over-power warn limit
0FFFh
0FFFh
Input over-power warning disabled
n/a
MFR_SPECIFIC_05: MFR_READ_PIN_PEAK (D5h)
The MFR_READ_PIN_PEAK command reports the maximum input power measured since a power-on reset or
the last MFR_CLEAR_PIN_PEAK command. To access the MFR_READ_PIN_PEAK command, use the PMBus
Read Word protocol. Use the Table 39.
Table 26. MFR_READ_PIN_PEAK Register
VALUE
MEANING
DEFAULT
0h – 0FFEh
Maximum value for input current x input voltage since reset or last
clear
0h
MFR_SPECIFIC_06: MFR_CLEAR_PIN_PEAK (D6h)
The MFR_CLEAR_PIN_PEAK command clears the MFR_PIN_PEAK register. This command uses the PMBus
Send Byte protocol.
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MFR_SPECIFIC_08: MFR_ALERT_MASK (D8h)
The MFR_ALERT_MASK command is used to mask the SMBA when a specific fault or warning has occurred.
Each bit corresponds to one of the 8 different analog and digital faults or warnings that would normally result in
an SMBA being asserted. When the corresponding bit is high, that condition will not cause the SMBA to be
asserted. If that condition occurs, the registers where that condition is captured will still be updated (STATUS
registers, DIAGNOSTIC_WORD) . This register is accessed with the PMBus Read and Write Word protocol.
Table 27. MFR_ALERT_MASK Definitions
28
BIT
NAME
DEFAULT
15
VOUT under-voltage warn
0
14
IIN limit warn
0
13
VIN under-voltage warn
0
12
VIN over-voltage warn
0
11
Not supported, always 0
0
10
Over-temperature warn
0
9
Not supported, always 0
0
8
Over-power warn
0
7
Not supported, always 0
0
6
Not supported, always 0
0
5
Not supported, always 0
0
4
Not supported, always 0
0
3
Not supported, always 0
0
2
Over-temperature fault
0
1
CML FAULT (communications fault)
0
0
Not supported, always 0
0
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MFR_SPECIFIC_09: MFR_DEVICE_SETUP (D9h)
The MFR_DEVICE_SETUP command may be used to override pin settings to define operation of the
LM5056/LM5056A under host control. This command is accessed with the PMBus read and write byte protocol.
Table 28. MFR_DEVICE_SETUP Byte Format
BIT
NAME
DEFAULT
7:5
Not supported, always 0
0
4
Current sense gain
(Default) 0 = High setting
(54.4mV)
3
Not supported, always 0
1 = Low setting (27.0mV)
0
(Default) 0 = Use pin settings
2
Current sense gain select configuration
1
Unused
0
0
Unused
0
1 = Use SMBus settings
In order to configure the current sense gain via this register, it is necessary to set the Current Sense Gain Select
Configuration bit (2) to 1 to enable the register to control the current sense gain and the Current Sense Gain bit
(4) to select the desired setting. If the Current Sense Gain Select Configuration bit is not set, the pin setting is
used.
NOTE
If the Current Sense Gain Select Configuration is changed, the samples for the telemetry
averaging function will not be reset. It is recommended to allow a full averaging update
period with the new Current Sense Gain before processing the averaged data.
The Current Sense Gain Select Configuration affects the coefficients used for the current
and power measurements and warning registers.
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MFR_SPECIFIC_10: MFR_BLOCK_READ (DAh)
The MFR_BLOCK_READ command concatenates the MFR_DIAGNOSTIC_WORD with input and output
telemetry information (IIN, VOUT, VIN, PIN) as well as TEMPERATURE to capture all of the operating
information of the LM5056/LM5056A in a single SMBus transaction. The block is 12 bytes long with telemetry
information being sent out in the same manner as if an individual READ_XXX command had been issued (shown
below). The contents of the MFR_BLOCK_READ register are updated every clock cycle (85 ns) as long as the
SMBus interface is idle. MFR_BLOCK_READ also ensures that the VIN, VOUT, IIN and PIN measurements are
all time-aligned. If separate commands are used, individual samples may not be time-aligned, because of the
delay necessary for the communication protocol. The MFR_BLOCK_READ command is read via the PMBus
block read protocol.
Table 29. MFR_BLOCK_READ Register Format
30
BYTE COUNT (ALWAYS 12)
(1 BYTE)
MFR_DIAGNOSTIC_WORD
(1 Word)
IIN_BLOCK
(1 Word)
VOUT_BLOCK
(1 Word)
VIN_BLOCK
(1 Word)
PIN_BLOCK
(1 Word)
TEMP_BLOCK
(1 Word)
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MFR_SPECIFIC_11: MFR_SAMPLES_FOR_AVG (DBh)
The MFR_SAMPLES_FOR_AVG command is a manufacturer specific command for setting the number of
samples used in computing the average values for IIN, VIN, VOUT, PIN. The decimal equivalent of the AVGN
nibble is the power of two samples, (e.g. AVGN = 12 equates to N = 4096 samples used in computing the
average). The LM5056/LM5056A supports average numbers of 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048,
4096. The MFR_SAMPLES_FOR_AVG number applies to average values of IIN, VIN, VOUT, PIN
simultaneously. The LM5056/LM5056A uses simple averaging. This is accomplished by summing consecutive
results up to the number programmed, then dividing by the number of samples. Averaging is calculated
according to the following sequence:
Y=
(X (N) + X (N - 1) + ... + X (0 ))
N
(2)
When the averaging has reached the end of a sequence (for example, 4096 samples are averaged), then a
whole new sequence begins that requires the same number of samples (in this example, 4096) to be taken
before the new average is ready.
Table 30. MFR_SAMPLES_FOR_AVG Register
AVGN
N = 2AVGN
AVERAGING AND REGISTER UPDATE
PERIOD (ms)
0000
1
1
0001
2
2
0010
4
4
0011
8
8
0100
16
16
0101
32
32
0110
64
64
0111
128
128
1000
256
256
1001
512
512
1010
1024
1024
1011
2048
2048
1100
4096
4096
NOTE
A change in the MFR_SAMPLES_FOR_AVG register are not reflected in the average
telemetry measurements until the present averaging interval has completed. The default
setting for AVGN is 0000, therefore, the average telemetry mirrors the instantaneous
telemetry until a value higher than zero is programmed.
The MFR_SAMPLES_FOR_AVG register is accessed via the PMBus read and write byte
protocol.
Table 31. MFR_SAMPLES_FOR_AVG Register
VALUE
MEANING
DEFAULT
0h – 0Ch
Exponent (AVGN) for number of samples to average over
00h
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MFR_SPECIFIC_12: MFR_READ_AVG_VIN (DCh)
The MFR_READ_AVG_VIN command will report the 12-bit ADC measured input average voltage. If the data is
not ready, the returned value is the previous averaged data. However, if there is no previously averaged data,
the default value (0000h) is returned. This data is read with the PMBus Read Word protocol. This register should
use the coefficients shown in the Table 39.
Table 32. MFR_READ_AVG_VIN Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Average of measured values for input voltage
0000h
MFR_SPECIFIC_13: MFR_READ_AVG_VOUT (DDh)
The MFR_READ_AVG_VOUT command reports the 12-bit ADC measured current sense average voltage. The
returned value is the default value (0000h) or previous data when the average data is not ready. This data is
read with the PMBus Read Word protocol. This register should use the coefficients shown in the Table 39.
Table 33. MFR_READ_AVG_VOUT Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Average of measured values for output voltage
0000h
MFR_SPECIFIC_14: MFR_READ_AVG_IIN (DEh)
The MFR_READ_AVG_IIN command reports the 12-bit ADC measured current sense average voltage. The
returned value is the default value (0000h) or previous data when the average data is not ready. This data is
read with the PMBus Read Word protocol. This register should use the coefficients shown in the Table 39.
Table 34. MFR_READ_AVG_IIN Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Average of measured values for current sense voltage
0000h
MFR_SPECIFIC_15: MFR_READ_AVG_PIN
The MFR_READ_AVG_PIN command reports the upper 12-bits of the average VIN x IIN product as measured
by the 12-bit ADC. Read the default value (0000h) or previous data when the average data is not ready. This
data is read with the PMBus Read Word protocol. This register should use the coefficients shown in the
Table 39.
Table 35. TABLE 35. MFR_READ_AVG_PIN Register
VALUE
MEANING
DEFAULT
0h – 0FFFh
Average of measured value for input voltage x input current sense
voltage
0000h
MFR_SPECIFIC_16: MFR_BLACK_BOX_READ (E0h)
The MFR_BLACK_BOX_READ command retrieves the MFR_BLOCK_READ data which was latched in at the
first assertion of SMBA by the LM5056/LM5056A. It is re-armed with the CLEAR_FAULTS command. It is the
same format as the MFR_BLOCK_READ registers, the only difference being that its contents are updated with
the SMBA edge rather than the internal clock edge. This command is read with the PMBus Block Read protocol.
32
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MFR_SPECIFIC_17: MFR_READ_DIAGNOSTIC_WORD (E1h)
The MFR_READ_DIAGNOSTIC_WORD PMBus command reports all of the LM5056/LM5056A faults and
warnings in a single read operation. The standard response to the assertion of the SMBA signal of issuing
multiple read requests to various status registers can be replaced by a single word read to the
MFR_DIAGNOSTIC_WORD register. The MFR_READ_DIAGNOSTIC_WORD command should be read with the
PMBus Read Word protocol. The MFR_READ_DIAGNOSTIC_WORD is also returned in the
MFR_BLOCK_READ, MFR_BLACK_BOX_READ, and MFR_AVG_BLOCK_READ operations.
Table 36. MFR_DIAGNOSTIC_WORD Format
BIT
MEANING
DEFAULT
15
VOUT under-voltage warn
0
14
Over-current warn or over-power warn
0
13
VIN under-votlage warn
0
12
VIN over-voltage warn
0
11
Not supported, always 1
1
10
Over-temperature warn
0
9
Not supported, always 0
0
8
Not supported, always 0
0
7
CONFIG_PRESET
1
6
Not supported, always 0
0
5
Not supported, always 0
0
4
Not supported, always 0
0
3
Not supported, always 0
0
2
Not supported, always 0
0
1
CML_FAULT
0
0
Not supported, always 0
0
MFR_SPECIFIC_18: MFR_AVG_BLOCK_READ (E2h)
The MFR_AVG_BLOCK_READ command concatenates the MFR_DIAGNOSTIC_WORD with input and output
average telemetry information (IIN, VOUT, VIN, PIN) as well as temperature to capture all of the operating
information of the part in a single PMBus transaction. The block is 12 bytes long with telemetry information being
sent out in the same manner as if an individual READ_AVG_XXX command had been issued (shown below).
MFR_AVG_BLOCK_READ also ensures that the VIN, VOUT, and IIN measurements are all time-aligned
whereas there is a chance they may not be if read with individual PMBus commands. To read data from the
MFR_AVG_BLOCK_READ command, use the SMBus Block Read protocol.
Table 37. MFR_AVG_BLOCK_READ Register Format
BYTE COUNT (ALWAYS 12)
(1 BYTE)
MFR_DIAGNOSTIC_WORD
(1 word)
AVG_IIN
(1 word)
AVG_VOUT
(1 word)
AVG_VIN
(1 word)
AVG_PIN
(1 word)
TEMPERATURE
(1 word)
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34
DIODE
VAUX
+48V
+
MFR_R EAD _AVG_PIN DFh
MFR _READ_AVG_VOU T DDh
MFR_READ_ PIN D2 h
READ_ VOUT 8Bh
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PEA K-HOLD
OT_FAULT_LIMIT 4Fh
OT_WARNING_LIMIT 5 1h
VOU T_ UV_WAR N_LIMIT 58h
MFR _PIN _OP_ WARN _LIMIT D 4h
MFR_ IIN_OC_ WARN_ LIMIT D 3h
VIN_ UV_WAR N_LIMIT 58h
VIN_OV_WARN_L IMIT 57h
WARNING
LIMITS
PMBus Interface
MFR_CL EAR_PIN_PEAK D 6h
MFR _READ_PIN_PEAK D5h
AVERAGED
DATA
MFR_READ _AVG_IIN DEh
MFR_READ _IIN D1h
READ_TEMPER ATUR E_ 1 8Dh
MFR _READ_ AVG_VIN DCh
ADC
READ_VIN 88h
MUX
VOUT
MFR_SAMPLES_FOR_ AVG DBh
VIN
IIN S/H
VOUT
SENSE
MFR_READ _VAUX D 0h
DATA
OUTPUT
VIN VIN_K
To load
CM P
CMP
CMP
CMP
CM P
CMP
CMP
MFR_ DIAGNOSTIC_WORD_R EAD E1h
OVER -TEMP FAULT
STATUS_TEMPERATU RE 7 Dh
OVER-TEMP WARN
STATUS_ TEMPERATURE 7Dh
VOUT UV WARN
STATUS_VOUT 7Ah
PIN OP WARN
STATUS_INPUT 7 Ch
IIN OC WARN
STATUS_INPUT 7 Ch
VIN U V WARN
STATUS_INPUT 7Ch
VIN OV WARN
STATUS_INPUT 7 Ch
WARNING
SYSTEM
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Figure 18. Command, Register and Alert Flow Diagram
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Reading and Writing Telemetry Data and Warning Thresholds
All measured telemetry data and user programmed warning thresholds are communicated in 12-bit two’s
compliment binary numbers read and written in 2-byte increments conforming to the direct format as described in
section 8.3.3 of the PMBus Power System Management Protocol Specification 1.1 (Part II). The organization of
the bits in the telemetry or warning word is shown in Table 38, where Bit_11 is the most significant bit (MSB) and
Bit_0 is the least significant bit (LSB). The decimal equivalent of all warning and telemetry words are constrained
to be within the range of 0 to 4095, with the exception of temperature. The decimal equivalent value of the
temperature word ranges from 0 to 65535.
Table 38. Telemetry and Warning Word Format
BYTE
B7
B6
B5
B4
1
Bit_7
Bit_6
Bit_5
Bit_4
2
0
0
0
0
B3
B2
B1
B0
Bit_3
Bit_2
Bit_1
Bit_0
Bit_11
Bit_10
Bit_9
Bit_8
Conversion from direct format to real-world dimensions of current, voltage, power, and temperature is
accomplished by determining appropriate coefficients as described in section 7.2.1 of the PMBus Power System
Management Protocol Specification 1.1 (Part II). According to this specification, the host system converts the
values received into a reading of volts, amperes, watts, or other units using the following relationship:
1
X=
Y ´ 10-R - B
m
(
)
where
•
•
•
•
•
X: the calculated real-world value (volts, amps, watt, etc.)
m: the slope coefficient
Y: a two byte two's complement integer received from device
b: the offset, a two byte, two's complement integer
R: the exponent, a one byte two's complement integer
(3)
R is only necessary in systems where m is required to be an integer (for example, where m may be stored in a
register in an integrated circuit). In those cases, R only needs to be large enough to yield the desired accuracy.
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Table 39. Telemetry and Warning Conversion Coefficients
FORMAT
NUMBER
OF DATA
BYTES
m
b
R
UNITS
READ_VIN MFR_READ_AVG_VIN
VIN_OV_WARN_LIMIT
VIN_UV_WARN_LIMIT
DIRECT
2
4612
-566
-2
V
READ_VOUT
MFR_READ_AVG_VOUT
VOUT_UV_WARN_LIMIT
DIRECT
2
4607
179
-2
V
MFR_READ_VAUX
DIRECT
2
13801
11
-1
V
COMMANDS
CONDITION
(1)
MFR_READ_IIN
MFR_READ_AVG_IIN
MFR_IIN_OC_WARN_LIMIT
CL = VDD
DIRECT
2
14985
4271
-2
A
(1)
MFR_READ_IIN
MFR_READ_AVG_IIN
MFR_IIN_OC_WARN_LIMIT
CL = GND
DIRECT
2
7471
1949
-2
A
(1)
MFR_READ_PIN
MFR_READ_AVG_PIN
MFR_READ_PIN_PEAK
MFR_PIN_OP_WARN_LIMIT
CL = VDD
DIRECT
2
1684
22344
-3
W
CL = GND
DIRECT
2
839
9822
-3
W
DIRECT
2
16000
0
-3
°C
(1)
MFR_READ_PIN
MFR_READ_AVG_PIN
MFR_READ_PIN_PEAK
MFR_PIN_OP_WARN_LIMIT
READ_TEMPERATURE_1
OT_WARN_LIMIT OT_FAULT_LIMIT
(1)
The coefficients relating to current/power measurements and warning thresholds shown in Table 39 are normalized to a sense resistor
(RS) value of 1mΩ. In general, the current/power coefficients can be calculated using the relationships shown in Table 40.
Table 40. Current and Power Telemetry and Warning Conversion Coefficients (RS in mΩ)
CONDITION
FORMAT
NUMBER
OF DATA
BYTES
m
b
R
UNITS
MFR_READ_IIN
MFR_READ_AVG_IIN
MFR_IIN_OC_WARN_LIMIT
CL = VDD
DIRECT
2
14985x RS
4271
-2
A
MFR_READ_IIN
MFR_READ_AVG_IIN
MFR_IIN_OC_WARN_LIMIT
CL = GND
DIRECT
2
7471 x RS
1949
-2
A
MFR_READ_PIN
MFR_READ_AVG_PIN
MFR_READ_PIN_PEAK
MFR_PIN_OP_WARN_LIMIT
CL = VDD
DIRECT
2
1684x RS
22344
-3
W
MFR_READ_PIN
MFR_READ_AVG_PIN
MFR_READ_PIN_PEAK
MFR_PIN_OP_WARN_LIMIT
CL = GND
DIRECT
2
839x RS
9822
-3
W
COMMANDS
Care must be taken to adjust the exponent coefficient, R, such that the value of m remains within the range of 32768 to 32767. For example, if a 5-mΩ sense resistor (RS) is used, the correct coefficients for the READ_IIN
command with CL = VDD would be m = 3736, b = 195, R = -1.
Note: The power coefficients given in Table 39 are characterized at a specific operating point of 48-V VIN. If
high-power accuracy is desired at voltages other than 48 V, it is recommended to read VIN and IIN using the
MFR_BLOCK_READ (DAh) command. After finding the real-world value of VIN and IIN using the coefficients, the
power can simply be calculated by the multiplication of the two measurements. This will ensure the user obtains
the highest accuracy power measurement. Another method to ensure accurate telemetry is to find new
coefficients for your specfic application. This is outlined in the proceeding section.
36
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Determining Telemetry Coefficients Empirically with Linear Fit
The coefficients for telemetry measurements and warning thresholds presented in Table 39 are adequate for the
majority of applications. Current and power coefficients must be calculated per application as they are dependent
on the value of the sense resistor, RS, used. Table 40 provides the equations necessary for calculating the
current and power coefficients for the general case. The small signal nature of the current measurement make it
and the power measurement more susceptible to PCB parasitics than other telemetry channels. This may cause
slight variations in the optimum coefficients (m, b, R) for converting from Direct format digital values to real-world
values (e.g., Amps and Watts). The optimum coefficients can be determined empirically for a specific application
and PCB layout using two or more measurements of the telemetry channel of interest. The current coefficients
can be determined using the following method:
1. While the LM5056/LM5056A is in normal operation measure the voltage across the sense resistor using
Kelvin test points and a high accuracy DVM while controlling the load current. Record the integer value
returned by the MFR_READ_AVG_IIN command (with the MFR_SAMPLES_FOR_AVG set to a value
greater than 0) for two or more voltages across the sense resistor. For best results, the individual
MFR_READ_AVG_IIN measurements should span nearly the full scale range of the current (For example,
voltage across RS of 5 mV and 20 mV).
2. Convert the measured voltages to currents by dividing them by the value of RS. For best accuracy the value
of RS should be measured. Table 41 assumes a sense resistor value of 5 mΩ.
Table 41. Measurements for Linear Fit Determination of Current Coefficients
MEASURED VOLTAGE ACROSS RS (V)
MEASURED CURRENT (A)
READ_AVG_IIN (integer value)
0.005
1
568
0.01
2
1108
0.02
4
2185
3. Using the spreadsheet or math program of your choice determine the slope and the y-intercept of the data
returned by the READ_AVG_IIN command versus the measured current. For the data shown in Table 41:
– READ_AVG_IN value = slope x (Measured Current) + (y-intercept)
– slope = 538.9
– y-intercept = 29.5
4. To determine the ‘m’ coefficient, simply shift the decimal point of the calculated slope to arrive at at integer
with a suitable number of significant digits for accuracy (typically 4) while staying with the range of -32768 to
+32767. This shift in the decimal point equates to the ‘R’ coefficient. For the slope value shown above, the
decimal point would be shifted to the right once hence R = -1.
5. Once the ‘R’ coefficient has been determined, the ‘b’ coefficient is found by multiplying the y-intercept by 10R. In this case the value of b = 295. Calculated current coefficients:
– m = 5389
– b = 295
– R = -1
1
X=
Y ´ 10-R - b
m
(
)
where
•
•
•
•
•
X: the calculated real-world value (volts, amps, watts, temperature)
m: the slope coefficient, is the two byte, two's complement integer
Y: a two byte two's complement integer received from device
b: the offset, a two byte, two's complement integer
R: the exponent, a one byte two's complement integer
(4)
The above procedure can be repeated to determine the coefficients of any telemetry channel simply by
substituting measured current for some other parameter (e.g., power, voltage, etc.). Note that the above
procedure can be executed using the PMBus software GUI found in the LM5056/LM5056A online product folder
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Writing Telemetry Data
There are several locations that require writing data if their optional usage is desired. Use the same coefficients
previously calculated for your application, and apply them using this method as prescribed by the PMBus revision
section 7.2.2 Sending a Value.
Y = (mX + b )´ 10R
where
•
•
•
•
•
X: the calculated real-world value (volts, amps, watts, temperature)
m: the slope coefficient, is the two byte, two's complement integer
Y: a two byte two's complement integer received from device
b: the offset, a two byte, two's complement integer
R: the exponent, a one byte two's complement integer
(5)
PMBus™ Address Lines (ADR0, ADR1, ADR2)
The three address lines are to be set high (connect to VDD), low (connect to GND), or open to select one of 27
addresses for communicating with the LM5056/LM5056A. Table 42 depicts 7-bit addresses (eighth bit is read
and write bit):
Table 42. Device Addressing
38
ADR2
ADR1
ADR0
DECODED ADDRESS
Z
Z
Z
40h
Z
Z
0
41h
Z
Z
1
42h
Z
0
Z
43h
Z
0
0
44h
Z
0
1
45h
Z
1
Z
46h
Z
1
0
47h
Z
1
1
10h
0
Z
Z
11h
0
Z
0
12h
0
Z
1
13h
0
0
Z
14h
0
0
0
15h
0
0
1
16h
0
1
Z
17h
0
1
0
53h
0
1
1
53h
1
Z
Z
53h
1
Z
0
53h
1
Z
1
54h
1
0
Z
56h
1
0
0
56h
1
0
1
57h
1
1
Z
58h
1
1
0
59h
1
1
1
5Ah
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SNVS827A – OCTOBER 2012 – REVISED APRIL 2013
tR
SCL
tF
t LOW
VIH
V IL
tHIGH
tHD;DAT
tHD;STA
tSU;STA
tSU;STO
t SU;DAT
SDA
VIH
VIL
tBUF
P
S
S
P
Figure 19. SMBus Timing Diagram
Table 43. SMBus Timing Definition
SYMBOL
PARAMETER
LIMITS
MIN
MAX
400
FSMB
SMBus operating frequency
10
TBUF
Bus free time between stop and start condition
1.3
THD:STA
Hold time after (repeated) start condition. After this period, the first clock is
generated.
0.6
TSU:STA
Repeated start condition setup time
0.6
TSU:STO
Stop condition setup time
0.6
THD:DAT
Data hold time
85
TSU:DAT
Data setup time
100
ns
25
TLOW
Clock low period
1.5
THIGH
Clock high period (2)
0.6
TLOW:SEXT
Clock high period (3)
25
TLOW:MEXT
Cumulative low extend time (master device) (4)
10
TF
TR
(1)
(2)
(3)
(4)
(5)
Clock or data fall time (5)
Clock or data rise time
(5)
kHz
μs
Clock low time-out (1)
TTIMEOUT
UNITS
35
ms
μs
20
300
20
300
ms
ns
Devices participating in a transfer will timeout when any clock low exceeds the value of TTIMEOUT,MIN of 25 ms. Devices that have
detected a timeout condition must reset the communication no later than TTIMEOUT,MAX of 35 ms. The maximum value must be
adhered to by both a master and a slave as it incorporates the cumulative stretch limit for both a master (10 ms) and a slave (25 ms).
THIGH MAX provides a simple method for devices to detect bus idle conditions.
TLOW:SEXT is the cumulative time a slave device is allowed to extend the clock cycles in one message from the initial start to the stop. If
a slave exceeds this time, it is expected to release both its clock and data lines and reset itself.
TLOW:MEXT is the cumulative time a master device is allowed to extend its clock cycles within each byte of a message as defined from
start-to-ack, ackto- ack, or ack-to-stop.
Rise and fall time is defined as follows:
(a) TR = (VILMAX – 0.15) to (VIHMIN + 0.15)
(b) TF = 0.9 VDD to (VILMAX – 0.15)
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SMBA Response
The SMBA effectively has two masks:
1. The Alert Mask Register at D8h, and
2. The ARA Automatic Mask.
The ARA Automatic Mask is a mask that is set in response to a successful ARA read. An ARA read operation
returns the PMBus address of the lowest addressed part on the bus that has its SMBA asserted. A successful
ARA read means that THIS part was the one that returned its address. When a part responds to the ARA read, it
releases the SMBA signal. When the last part on the bus that has an SMBA set has successfully reported its
address, the SMBA signal de-asserts.
The way that the LM5056/LM5056A releases the SMBA signal is by setting the ARA Automatic mask bit for all
fault conditions present at the time of the ARA read. All status registers still show the fault condition, but it is not
generated and SMBA on that fault again until the ARA Automatic mask is cleared by the host issuing a
CLEAR_FAULTS command to this part. This should be done as a routine part of servicing an SMBA condition on
a part, even if the ARA read is not done. Figure 20 depicts a schematic version of this flow.
From other
fault inputs
SMBA
Fault Condition
Alert Mask D8h
From PMBus
Set
ARA Operation Flag Succeeded
Clear_Fault Command Received
ARA Auto Mask
Clear
Figure 20. Typical Flow Schematic for SMBA Fault
40
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
(3)
Device Marking
(4/5)
(6)
LM5056APMH/NOPB
ACTIVE
HTSSOP
PWP
28
48
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
LM5056APMH
LM5056APMHE/NOPB
ACTIVE
HTSSOP
PWP
28
250
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
LM5056APMH
LM5056APMHX/NOPB
ACTIVE
HTSSOP
PWP
28
2500
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
LM5056APMH
LM5056PMH/NOPB
ACTIVE
HTSSOP
PWP
28
48
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
LM5056PMH
LM5056PMHE/NOPB
ACTIVE
HTSSOP
PWP
28
250
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
LM5056PMH
LM5056PMHX/NOPB
ACTIVE
HTSSOP
PWP
28
2500
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
LM5056PMH
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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