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MAX34408/MAX34409 SMBus Dual/Quad Current Monitor

General Description

The MAX34408/MAX34409 are two- and four-channel

current monitors that are configured and monitored with a

standard I

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.

Applications

● NetworkSwitchesandRouters

● BaseStations

● Servers

● SmartGridNetworkSystems

● IndustrialControls

Benets 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

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

19-6792; Rev 1; 1/15

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

EVALUATION KIT AVAILABLE

AMPLIFIER 2

AMPLIFIER 3

AMPLIFIER 4

NOT PRESENT

ON MAX34408

2 OR

AUTOMATIC

SEQUENCING

DIGITAL

COMPARATOR

VREF

SHUTDOWN

DELAY

RESET

LATCH AND DELAY RESET

SHUTDOWN DELAY RESET

SHUTDOWN

LATCH

POWER

CONTROL

GND

ENA

SHTDN

2.7V TO

3.6V

OVER-

CURRENT

DETECTION

DELAY

REGISTERS

SMBus

INTERFACE

SCL

AVERAGING

EP (EXPOSED PAD)

MAX34408/MAX34409

CURRENT-

SENSE

AMPLIFIER

MUX

AMPLIFIER 1

SDA

ALERT

ADDR

ADC

IN-

IN+

1µF

100Ω

SENSE

CURRENT

FLOW

OPTIONAL

FILTER

NETWORK

Summary of content (19 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX34408/MAX34409 SMBus Dual/Quad Current Monitor General Description The MAX34408/MAX34409 are two- and four-channel current monitors that are configured and monitored with a standard I2C/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.
PAGE 2
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Absolute Maximum Ratings Voltage Range on VDD 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 (VDD + 0.3V) (not to exceed +4V) Differential Input Voltage, IN+ to IN-....................................±16V Continuous Power Dissipation (TA = +70°C) 16-Pin TQFN (derate 25mW/°C above +70°C)..........2000mW Operating Temperature Range.....
PAGE 3
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Electrical Characteristics (continued) (VIN+ = VIN- = 12V, VSENSE = 0V, VDD = 2.7V to 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = 3.3V and TA = +25°C.) (Notes 2, 3) PARAMETER Output Logic Low (SHTDN, ALERT) SYMBOL VOL CONDITIONS MIN TYP IOL = 4mA Output Leakage (SHTDN, ALERT) SCL, SDA Leakage VDD = 0V or float ENA Leakage MAX UNITS 0.
PAGE 4
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Timing Diagrams 2.5V VDD SMBus tSMBD NOT ACTIVE ACTIVE 2V IN+ tCSAD CURRENT MONITORING NOT ACTIVE ACTIVE Figure 1. Delay Timing SDA tBUF tF tLOW tHD:STA tSP SCL tHD:STA tHIGH tR tHD:DAT STOP START tSU:STA tSU:STO tSU:DAT REPEATED START NOTE: TIMING IS REFERENCED TO VIL(MAX) AND VIH(MIN). Figure 2. I2C/SMBus Timing www.maximintegrated.
PAGE 5
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Typical Operating Characteristics (VDD = 3.3V and TA = +25°C, common-mode voltage = 12.0V, unless otherwise noted.) SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. TEMPERATURE toc01 0.80 toc02 0.80 13.5 0.65 FULL SCALE (mV) 0.70 toc03 14.0 0.75 IDD (mA) 0.75 IDD (mA) IN INPUT FULL SCALE vs. TEMPERATURE 0.70 0.65 13.0 12.5 12.0 11.5 0.60 2.6 2.8 3.0 3.2 3.4 3.6 0.60 3.8 -50 -30 VDD (V) 10 30 50 70 11.
PAGE 6
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor ENA SHTDN N.C. IN4+ ENA SHTDN IN3- 12 11 10 9 12 11 10 9 VDD 15 *EP 1 2 3 4 SDA SCL IN2+ + IN1- IN1+ 16 IN4- 13 7 GND ADDR 14 6 ALERT VDD 15 5 IN2- IN1+ 16 MAX34409 *EP + 1 2 3 4 IN2+ MAX34408 N.C. SCL ADDR 14 8 SDA N.C. 13 IN1- TOP VIEW N.C. Pin Configurations 8 IN3+ 7 GND 6 ALERT 5 IN2- 16 TQFN (4mm x 4mm x 0.
PAGE 7
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Pin Description (continued) PIN NAME FUNCTION MAX34408 MAX34409 15 15 VDD Supply Voltage for Comparators and Logic. A +2.7V to +3.6V supply. This pin should be decoupled to GND with a 100nF ceramic capacitor. 16 16 IN1+ External Sense Resistor Power-Side Connection for Amplifier 1. This pin should be left open circuit if not needed. — 8 IN3+ External Sense Resistor Power-Side Connection for Amplifier 3.
PAGE 8
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Table 1. Read Byte Format 1 7 1 1 8 1 1 7 1 1 8 1 1 S Slave Address W A Command Code A SR Slave Address R A Data Byte NA P Table 2. Write Byte Format 1 7 S Slave Address 1 W 1 8 A Command Code 1 8 1 1 A Data Byte A P Table 3. Receive Byte Format (reads data from the last transacted command code) 1 7 1 1 8 1 1 S Slave Address R A Data Byte NA P Key: S = Start SR = Repeated Start Table 4.
PAGE 9
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor SMBus Commands A summary of the SMBus commands supported by the devices are described in the following sections, see Table 6. Table 6.
PAGE 10
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor STATUS (00h) The STATUS command returns 1 byte of information with a summary of the fault conditions along with the real-time status of the ENA and SHTDN pins. The STATUS byte message content is described in Table 7. See Figure 3 for STATUS bits 3:0 organization. Table 7.
PAGE 11
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor CONTROL (01h) The CONTROL command configures the digital current-sensing averaging function. The CONTROL command also defines if the devices respond to the Alert Response Address. The CONTROL byte command is described in Table 8. Table 8.
PAGE 12
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor OVER_CURRENT_DELAY (02h) The OVER_CURRENT_DELAY command configures and resets the overcurrent delay counters. The OVER_CURRENT_DELAY byte command is described in Table 9. See Figure 4 for delay counter timing. Table 9.
PAGE 13
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor CURRENT OVERCURRENT THRESHOLD 3ms DELAY OVERCURRENT DELAY COUNTER 7ms DELAY SHUTDOWN DELAY COUNTER OC STATUS BIT ALERT SHTDN ARA BUS TRANSACTION STATUS BYTE WRITE (0 TO OCn BIT POSITION) Figure 4. Delay Timing www.maximintegrated.
PAGE 14
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor SHUTDOWN_DELAY (03h) The SHUTDOWN_DELAY command configures and resets the shutdown delay counters. The SHUTDOWN_DELAY byte command is described in Table 10. Table 10.
PAGE 15
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor OVER_CURRENT_THRESHOLD_1/2/3/4 (08h/09h/0Ah/0Bh) The OVER_CURRENT_THRESHOLD_1/2/3/4 command sets the overcurrent threshold for each channel. The OVER_CURRENT_THRESHOLD_1/2/3/4 byte command is described in Table 12. See Table 13 for the configuration formula and Table 14 for an example. Table 12.
PAGE 16
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor DATE_CODE_YEAR (0Dh) The DATE_CODE_YEAR command returns a factory programmed date code. The DATE_CODE_YEAR byte command is described in Table 16. Table 16. DATE_CODE_YEAR (0Dh)—Read Byte BIT NAME BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0 0 YY5 YY4 YY3 YY2 YY1 YY0 POR BIT Factory Set NAME DESCRIPTION These bits report the last two decimal digits of the calendar year in which the device was tested.
PAGE 17
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Applications Information Kelvin Connections Sense Resistor, RSENSE Adjust the RSENSE value to monitor higher or lower current levels. Select RSENSE based on the following criteria: Resistor Value: Select an RSENSE resistor value in which the largest expected current results in a 10mV full-scale current-sense voltage.
PAGE 18
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Optional Filter Network For noisy environments, a simple lowpass filter can be placed at the devices’ amplifier inputs as shown in Figure 7. The 100Ω resistor and 1µF capacitor provide a 1.6kHz rolloff frequency. To achieve the most effective results, use the filter in conjunction with the device’s digital averaging as described in the CONTROL (01h) section.
PAGE 19
MAX34408/MAX34409 SMBus Dual/Quad Current Monitor Revision History REVISION NUMBER REVISION DATE 0 9/13 Initial release — 1 1/15 Updated Benefits and Features section 1 DESCRIPTION PAGES CHANGED For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product.