Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - PoE controller TSSOP 28 Controller (PSE)

General Description

The MAX5922A/B/C is a single-port network power con-

troller with an integrated power MOSFET, operating from

a +32V to +60V supply rail. The device is specifically

designed for power-sourcing equipment (PSE) in power-

over-LAN applications and is fully compliant to the IEEE

802.3af standard. The MAX5922 provides power devices

(PD) discovery, classification, current limit, and other nec-

essary functions for an IEEE 802.3af compliant PSE.

The MAX5922 is suitable for PSE function in both

switch/router systems where the power is delivered to the

load through the signal pairs, and in midspan systems

where the power is delivered to the load through the

spare pairs. In midspan mode, a detection collision

avoidance circuit (MAX5922A/C only) provides the nec-

essary back-off timing to prevent fault detections that

happen when two different PSEs try to detect and

power the same PD. The MAX5922B/C have a detec-

tion disable input that can be connected high to disable

the detection/classification functions or connected low

to enable them.

The MAX5922 features a programmable undervoltage

lockout (UVLO) that keeps the device in shutdown until

the input voltage exceeds a certain threshold, set to 38V

(MAX5922A) or 28V (MAX5922B/C) internally. After suc-

cessfully discovering and classifying a PD, the MAX5922

enters startup mode. During startup, the MAX5922 limits

the output voltage and current slew rate to minimize EMI

(electromagnetic interference). The MAX5922 has an inte-

grated 0.45Ω N-channel power MOSFET that provides

efficient operation and simplified system design. The

MAX5922 monitors and provides current-limit protection

to the load at all times. The current limit is programmable

using an external current-sensing resistor. The MAX5922

features current-limit foldback and duty-cycle limit to

ensure robust operation during load-fault and short-circuit

conditions. Fault management allows the part to either

latch-off or autorestart after a fault.

The MAX5922 provides POK, ZC, and FAULT status sig-

nals to indicate output power is good, zero-current fault,

and other faults (overcurrent, overtemperature), respec-

tively. The MAX5922 is available in a 28-pin TSSOP pack-

age and is rated over the extended -40°C to +85°C

temperature range.

Features

♦ IEEE 802.3af Compliant

♦ +32V to +60V Wide Operating Input Range

♦ 0.45Ω Integrated Power Switch

♦ Power Device (PD) Detection and Classification

♦ 100µA PD Leakage Detection Tolerant

♦ Programmable Current Limit

♦ Zero-Current Detection with Status Output

♦ Detection Collision Avoidance Option for Midspan

Application

♦ Input Logic Signals Compatible with 1.8V to 5V

CMOS Logic

♦ Separate Analog and Digital Grounds with Up to

±4V Offset

♦ Power-Good Status Output

♦ Overcurrent and Overtemperature Protection with

Status Outputs

♦ Current-Limit Foldback with Timeout and Duty-

Cycle Control

♦ Latch or Autorestart Fault Management

Applications

MAX5922

+48V, Single-Port Network Power Switch

For Power-Over-LAN

________________________________________________________________ Maxim Integrated Products 1

19-2708; Rev 0; 4/03

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART TEMP RANGE PIN-PACKAGE

MAX5922AEUI -40°C to +85°C 28 TSSOP

MAX5922BEUI -40°C to +85°C 28 TSSOP

MAX5922CEUI -40°C to +85°C 28 TSSOP

Ordering Information

Typical Application Circuits, Selector Guide, and Pin

Configuration appear at end of data sheet.

Power-Sourcing Equipment (PSE)

Power-Over-LAN/Power-Over-MDI

(Media-Dependent Interface)

Computer Telephony

Single-Port Power Injector/Adapter

Midspan Power Injector

Switches/Routers with In-Line Power

Summary of content (21 pages)

PAGE 1
9-2708; Rev 0; 4/03 +48V, Single-Port Network Power Switch For Power-Over-LAN The MAX5922 features a programmable undervoltage lockout (UVLO) that keeps the device in shutdown until the input voltage exceeds a certain threshold, set to 38V (MAX5922A) or 28V (MAX5922B/C) internally. After successfully discovering and classifying a PD, the MAX5922 enters startup mode. During startup, the MAX5922 limits the output voltage and current slew rate to minimize EMI (electromagnetic interference).
PAGE 2
MAX5922 +48V, Single-Port Network Power Switch For Power-Over-LAN ABSOLUTE MAXIMUM RATINGS (All voltages with respect to AGND_S, unless otherwise noted.) IN ............................................................................-0.3V to +76V UVLO ........................................................................-0.3V to +6V VDIG to DGND ..........................................................-0.3V to +6V OUT .......................................................-0.3V to (VDRAIN + 0.
PAGE 3
+48V, Single-Port Network Power Switch For Power-Over-LAN (VIN = 48V, VDIG = 3.3V, AGND_S = AGND = DGND = 0V, RSENSE = 0.5Ω ±1%, UVLO = open, EN = VDIG, RRCL = 150Ω ±1%, RRDT = 18.2kΩ ±1%, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER POK Output Delay (Note 6) Zero-Current Detection Threshold Voltage (VIN - VDRS) ZC Output Low Voltage SYMBOL MIN TYP POK from high to low, VOUT falling 1.0 1.4 1.
PAGE 4
MAX5922 +48V, Single-Port Network Power Switch For Power-Over-LAN ELECTRICAL CHARACTERISTICS (continued) (VIN = 48V, VDIG = 3.3V, AGND_S = AGND = DGND = 0V, RSENSE = 0.5Ω ±1%, UVLO = open, EN = VDIG, RRCL = 150Ω ±1%, RRDT = 18.2kΩ ±1%, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS V PD DETECTION (See Figure 3, PD Detection Section) Detection Probe Voltage Phase I VPBI RPD = 19kΩ to 26.5kΩ 3.6 4 4.
PAGE 5
+48V, Single-Port Network Power Switch For Power-Over-LAN 0.85 TA = +25°C 12.0 VIN = 60V 11.9 11.8 11.7 0.90 IDIG (µA) TA = +85°C 0.80 0.95 SUPPLY CURRENT (mA) 0.95 MEASURED AT AGND MAX5922 toc02 MEASURED AT AGND SUPPLY CURRENT (mA) 1.00 MAX5922 toc01 1.00 0.90 DIGITAL SUPPLY CURRENT vs. TEMPERATURE VIN SUPPLY CURRENT vs. TEMPERATURE MAX5922 toc03 VIN SUPPLY CURRENT vs. INPUT VOLTAGE VIN = 48V 0.85 11.6 11.5 11.4 0.80 TA = -40°C 0.75 0.75 0.70 0.70 11.3 VIN = 32V 11.2 11.
PAGE 6
Typical Operating Characteristics (continued) (MAX5922A, VIN = 48V, VDIG, EN, LATCH, CLASS, and ZC_EN = 3.3V, DCA, AGND_S = AGND = DGND = 0V, RSENSE = 0.5Ω ±1%, UVLO floating, RRCL = 150kΩ, RRDT = 18.2kΩ, TA = +25°C, unless otherwise noted.) OVERCURRENT TIMEOUT (RLOAD FROM 240Ω TO 75Ω) DIGITAL SUPPLY CURRENT vs.
PAGE 7
+48V, Single-Port Network Power Switch For Power-Over-LAN ZERO-CURRENT (IIms GLITCH) DEGLITCH TIME ZERO-CURRENT HIGH-TO-LOW DETECTION TIME MAX5922 toc17 MAX5922 toc16 20V/div VOUT 0V 5V/div 0V 5V/div 0V VOUT 20V/div 0V POK 5V/div 0V POK ZC tZCDEL 5V/div 0V ZC GLITCH > tZC_DEG IOUT 1.
PAGE 8
MAX5922 +48V, Single-Port Network Power Switch For Power-Over-LAN Typical Operating Characteristics (continued) (MAX5922A, VIN = 48V, VDIG, EN, LATCH, CLASS, and ZC_EN = 3.3V, DCA, AGND_S = AGND = DGND = 0V, RSENSE = 0.5Ω ±1%, UVLO floating, RRCL = 150kΩ, RRDT = 18.2kΩ, TA = +25°C, unless otherwise noted.
PAGE 9
+48V, Single-Port Network Power Switch For Power-Over-LAN STARTUP WITH VALID PD (25kΩ, ZC_EN = LOW) STARTUP WITH DIFFERENT PD CLASSES MAX5922 toc28 MAX5922 toc29 VOUT 20V/div VOUT 0V 0V 5V/div 0V 5V/div 0V POK 0V EN CLASS 4 IOUT 1.
PAGE 10
+48V, Single-Port Network Power Switch For Power-Over-LAN MAX5922 Pin Description PIN NAME FUNCTION * AGND Analog Ground. This is the return of analog power input. AGND can vary ±4V from DGND. AGND and DGND must be connected together at a single point in the system. 1, 2 DRAIN Drain connection for the integrated MOSFET. Connect a sense resistor, RSENSE, from DRAIN to IN. These pins are also the current-sense resistor negative terminal.
PAGE 11
+48V, Single-Port Network Power Switch For Power-Over-LAN PIN NAME FUNCTION Zero-Current-Detection Enable Logic Input. Referenced to DGND. Connect ZC_EN to a logic high to enable the zero-current detection circuitry. Connect ZC_EN to a logic low to disable this function. 21 ZC_EN 22 EN 23 VDIG Digital Supply Voltage. VDIG is the supply voltage for the internal digital logic circuity. EN, LATCH, CLASS, DET_DIS, DCA, and ZC_EN input logic thresholds are automatically scaled to the voltage on VDIG.
PAGE 12
MAX5922 +48V, Single-Port Network Power Switch For Power-Over-LAN Detailed Description The MAX5922 is a single-port network power controller with an integrated power MOSFET, operating from a +32V to +60V supply rail. The device is specifically designed for PSE in power-over-LAN applications and is fully compliant to the IEEE 802.3af standard. The MAX5922 provides PD discovery, classification, current limit, and other necessary functions for an IEEE 802.3afcompliant PSE.
PAGE 13
+48V, Single-Port Network Power Switch For Power-Over-LAN N RESET COUNTERS START PD DECTECTION FORCE OUT = VPBI (4V) WAIT I/2tDET Cl0 = CL1 = CL2 = HIGH Y POWER-ON RESET MAX5922 N Y EN = HIGH? VIN > UVLOTH? SAMPLE AND HOLD ISENSE1 N EN = LOW? Y Y N tRESTART ELAPSED? REPORT CLASS STATUS Y MEASURE IDET = ISENSE2 - ISENSE1 START PD CLASSIFICATION CL0 = CL1 = CL2 = HIGH Y LATCH = HIBH FORCE OUT = VPBI (8V) WAIT 1/2tDET FORCE VOUT = VCLASS (17.
PAGE 14
MAX5922 +48V, Single-Port Network Power Switch For Power-Over-LAN POWER DEVICE INTERNAL TO MAX5922 27, 28 OUT IMAX = 1.5mA RPD D1 VPROBE_VOLTAGE 7 AGND_S Figure 3.
PAGE 15
+48V, Single-Port Network Power Switch For Power-Over-LAN MAX5922 UVLO VIN 8V VOUT 4V 0V t tDET1 = 88ms tDET2 = 88ms Figure 5. PD Detection with an Invalid PD Signature Table 2. PD Classification Threshold Limits CL2 CL1 CL0 0.
PAGE 16
MAX5922 +48V, Single-Port Network Power Switch For Power-Over-LAN +48V 100V/ms (max) +17.5V +8V VIN CROSSES UVLO +4V 0V POK (OPEN-DRAIN) 0V t 0 tDET1, 88ms tPOK_HIGH, 88ms tDET2, 88ms tCLASS, 21.3ms Figure 6. Startup Sequence output voltage slew rate at the OUT pin to dVOUT/dt = 100V/ms (max) and the output-current slew rate out of the OUT pin to dIOUT/dt = 35A/ms (max). The MAX5922 has an integrated 0.45Ω N-channel power MOSFET.
PAGE 17
+48V, Single-Port Network Power Switch For Power-Over-LAN IN R1 MAX5922 UVLO R2 AGND_S Figure 7. Setting Undervoltage Lockout with an External Resistive-Divider Digital Logic VDIG is the input supply for the internal logic circuitry. The logic input thresholds of EN, LATCH, CLASS, DCA (MAX5922A), DET_DIS (MAX5922B/MAX5922C), and ZC_EN are CMOS compatible and are determined by the voltage at V DIG which can range from 1.65V to 5.5V. The POK, ZC, CL0, CL1, CL2, and FAULT outputs are open drain.
PAGE 18
MAX5922 +48V, Single-Port Network Power Switch For Power-Over-LAN This overcurrent timeout enables the MAX5922 to operate in a periodic overcurrent condition without causing a fault (see Figure 9). Power-OK (POK) POK goes open-drain tPOK_HIGH (88ms) after VOUT rises to within VTHPOK (0.75V) from VIN. POK goes low tPOK_LOW (1.4ms) after VOUT drops 0.82V below VIN.
PAGE 19
+48V, Single-Port Network Power Switch For Power-Over-LAN PART PIN-PACKAGE DETECTION COLLISION AVOIDANCE MAX5922AEUI 28 TSSOP Selectable — MAX5922BEUI 28 TSSOP Disabled Selectable MAX5922CEUI 28 TSSOP Enabled Selectable Pin Configuration PD DETECTION DISABLE Chip Information TRANSISTOR COUNT: 8687 PROCESS: BiCMOS TOP VIEW DRAIN 1 28 OUT DRAIN 2 27 OUT N.C. 3 26 N.C. 25 DET_DIS (DCA) IN 4 24 CLASS RCL 5 N.C.
PAGE 20
+48V, Single-Port Network Power Switch For Power-Over-LAN MAX5922 Typical Application Circuits +48V POWER OVER SIGNAL PAIRS LAN SWITCH RJ45 +48V IN RJ45 +48V OUT PD MAX5922A/MAX5922B CAT5 POWERED DEVICE (IP PHONES, WIRELESS LAN ACCESS NODE, SECURITY CAMERA, ETC.) DATA POWER SENT OVER SIGNAL PAIRS +48V POWER OVER SPARE PAIRS RJ45 RJ45 CAT5 MIDSPAN HUB RJ45 +48V IN PD MAX5922A/MAX5922C CAT5 POWERED DEVICE (IP PHONES, WIRELESS LAN ACCESS NODE, SECURITY CAMERA, ETC.
PAGE 21
+48V, Single-Port Network Power Switch For Power-Over-LAN TSSOP4.40mm.EPS Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.