current monitors that are configured and monitored with a
standard I
2
C/SMBus serial interface. Each unidirectional
current sensor offers precision high-side operation with a
low full-scale sense voltage. The devices automatically
sequence through two or four channels and collect the
current-sense samples and average them to reduce the
effect of impulse noise. The raw ADC samples are com-
pared to user-programmable digital thresholds to indicate
overcurrent conditions. Overcurrent conditions trigger a
hardware output to provide an immediate indication to
shut down any necessary external circuitry.
Benefits and Features
● Enables Accurate Current Consumption Measurement
on Up to Four Rails with Digital Serial Readout
• Low 12.25mV Full-Scale Current-Sense Voltage
•
Automatic Round Robin Sequencing to Sample
Each Current-Sense Input
• Selectable Averaging to Improve Current-Sense
Accuracy
• Programmable Digital Overcurrent Thresholds with
Delay Function
• I
2
C/SMBus Interface with Bus Timeout
•
Register Access to Real-Time Current Measurements
● Compatible on a Wide Range of Voltage Rails
•
Wide 2.5V to 13.2V Common-Mode Range
● Automatic System Shutdown on Overcurrent Condition
• Shutdown Output Provides Immediate Hardware
Indication of Overcurrent
Applications
●
●
●
●
●
Network Switches and Routers
Base Stations
Servers
Smart Grid Network Systems
Industrial Controls
Ordering Information
appears at end of data sheet.
For related parts and recommended products to use with this part, refer
to
www.maximintegrated.com/MAX34408.related.
Typical Application Circuit and Block Diagram
V
DD
2.7V TO
3.6V
POWER
CONTROL
GND
AUTOMATIC
SEQUENCING
AMPLIFIER 4
AMPLIFIER 3
AMPLIFIER 2
100Ω
1µF
100Ω
1µF
IN-
2 OR
4
CURRENT-
SENSE
AMPLIFIER
IN+
2 OR
4
AMPLIFIER 1
MUX
OR
LATCH AND DELAY RESET
ENA
MAX34408/MAX34409
NOT PRESENT
ON MAX34408
OPTIONAL
FILTER
NETWORK
RESET
SHUTDOWN
DELAY
SHUTDOWN DELAY RESET
VREF
DIGITAL
COMPARATOR
AVERAGING
OVER-
CURRENT
DETECTION
DELAY
SHUTDOWN
LATCH
CURRENT
FLOW
SHTDN
R
SENSE
REGISTERS
ADC
SCL
SMBus
INTERFACE
SDA
ALERT
ADDR
EP (EXPOSED PAD)
R
ADDR
19-6792; Rev 1; 1/15
MAX34408/MAX34409
SMBus Dual/Quad Current Monitor
Absolute Maximum Ratings
Voltage Range on V
DD
Relative to GND
................-0.3V to +4V
Voltage Range on IN+, IN- Relative to GND
.........-0.3V to +16V
Voltage Range on All Other Pins
Relative to GND...
-0.3V to (V
DD
+ 0.3V) (not to exceed +4V)
Differential Input Voltage, IN+ to IN-
...................................±16V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin TQFN (derate 25mW/°C above +70°C)
.........2000mW
Operating Temperature Range
........................... -40°C to +85°C
Storage Temperature Range
............................ -55°C to +125°C
Soldering Temperature (reflow) .......................................+260°C
Lead Temperature (soldering, 10s)
................................. +300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Package Thermal Characteristics
(Note 1)
TQFN
Junction-to-Ambient Thermal Resistance (θ
JA
)...........40°C/W
Junction-to-Case Thermal Resistance (θ
JC
)..................6°C/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to
www.maximintegrated.com/thermal-tutorial.
Recommended DC Operating Conditions
(T
A
= -40°C to +85°C.) (Notes 2, 3)
PARAMETER
V
DD
Operating Voltage Range
Input Logic 1: ENA Pin
Input Logic 0: ENA Pin
Input Logic 1: SCL/SDA Pins
Input Logic 0: SCL/SDA Pins
SYMBOL
V
DD
V
IH1
V
IL1
V
IH2
V
IL2
CONDITIONS
MIN
2.7
V
DD
x
0.7
-0.3
2.1
-0.3
TYP
MAX
3.6
V
DD
+
0.3
+0.3 x V
DD
V
DD
+ 0.3
+0.8
UNITS
V
V
V
V
V
Electrical Characteristics
(V
IN+
= V
IN-
= 12V, V
SENSE
= 0V, V
DD
= 2.7V to 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
DD
= 3.3V
and T
A
= +25°C.) (Notes 2, 3)
PARAMETER
Supply Current
Current-Sense Common-Mode
Input Range
Input Bias Current (IN+/IN-)
ADC Resolution
Per-Channel Current
Sample Rate
IN Input Full Scale
ADC INL
ADC DNL
IN Input Offset
12.00
Common-mode voltage = 13.2V, IN input
differential = 12.25mV
8
1
12.25
±0.5
±0.5
±0.5
12.50
±2
±2
±4
SYMBOL
I
DD
SMBus idle
2.5
2
CONDITIONS
MIN
TYP
830
13.2
MAX
UNITS
µA
V
µA
Bits
ksps
mV
LSB
LSB
LSB
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Maxim Integrated
│
2
MAX34408/MAX34409
SMBus Dual/Quad Current Monitor
Electrical Characteristics (continued)
(V
IN+
= V
IN-
= 12V, V
SENSE
= 0V, V
DD
= 2.7V to 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
DD
= 3.3V
and T
A
= +25°C.) (Notes 2, 3)
PARAMETER
Output Logic Low
(SHTDN, ALERT)
Output Leakage
(SHTDN, ALERT)
SCL, SDA Leakage
ENA Leakage
Digital Comparator Resolution
Delay Time from V
DD
Applied
Until SMBus Active (Figure 1)
Delay Time from Common-Mode
Voltage Applied Until Current
Monitoring Active (Figure 1)
t
SMBD
8
500
V
DD
= 0V or float
SYMBOL
V
OL
I
OL
= 4mA
CONDITIONS
MIN
TYP
MAX
0.4
±1
±5
±1
UNITS
V
µA
µA
µA
Bits
µs
t
CSAD
10
ms
AC Electrical Characteristics: I
2
C/SMBus Interface
(V
DD
= 2.7V to 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
DD
= 3.3V, T
A
= +25°C.) (Notes 3, 4)
(Figure
2)
PARAMETER
SCL Clock Frequency
Bus Free Time Between
STOP and START Conditions
Hold Time (Repeated)
START Condition
Low Period of SCL
High Period of SCL
Data Hold Time
Data Setup Time
Start Setup Time
SDA and SCL Rise Time
SDA and SCL Fall Time
Stop Setup Time
Clock Low Timeout
SYMBOL
f
SCL
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
HD:DAT
t
SU:DAT
t
SU:STA
t
R
t
F
t
SU:STO
t
TO
0.6
25
35
Receive
Transmit
CONDITIONS
MIN
10
1.3
0.6
1.3
0.6
0
300
100
0.6
300
300
TYP
MAX
400
UNITS
kHz
µs
µs
µs
µs
ns
ns
µs
ns
ns
µs
ms
Note 2:
All voltages are referenced to ground. Current entering the device are specified as positive and currents exiting the device
are negative.
Note 3:
Limits are 100% production tested at T
A
= +25°C. Limits over the operating temperature range and
relevant supply voltage range are guaranteed by design and characterization.
Note 4:
All timing specifications are guaranteed by design.
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Maxim Integrated
│
3
MAX34408/MAX34409
SMBus Dual/Quad Current Monitor
Timing Diagrams
2.5V
V
DD
SMBus
t
SMBD
NOT ACTIVE
ACTIVE
2V
IN+
CURRENT
MONITORING
NOT ACTIVE
t
CSAD
ACTIVE
Figure 1. Delay Timing
SDA
t
BUF
t
LOW
SCL
t
HIGH
t
HD:DAT
STOP
START
t
SU:DAT
REPEATED
START
t
F
t
HD:STA
t
SP
t
HD:STA
t
R
t
SU:STA
t
SU:STO
NOTE:
TIMING IS REFERENCED TO V
IL(MAX)
AND V
IH(MIN)
.
Figure 2. I
2
C/SMBus Timing
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Maxim Integrated
│
4
MAX34408/MAX34409
SMBus Dual/Quad Current Monitor
Typical Operating Characteristics
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
0.80
toc01
(V
DD
= 3.3V and T
A
= +25°C, common-mode voltage = 12.0V, unless otherwise noted.)
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