MAX5953A MAXIM [Maxim Integrated Products], MAX5953A Datasheet

MAX5953A

Manufacturer Part Number

MAX5953A

Description

IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs

Manufacturer

MAXIM [Maxim Integrated Products]

Datasheet

1.MAX5953A.pdf (27 pages)

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MAX5953AUTM+

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Maxim Integrated Products

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The MAX5953A/MAX5953B/MAX5953C/MAX5953D

integrate a complete power IC solution for Powered

Devices (PD) in a Power-Over-Ethernet (PoE) system, in

compliance with the IEEE 802.3af standard. The

MAX5953A/MAX5953B/MAX5953C/MAX5953D provide

the PD with a detection signature, a classification sig-

nature, and an integrated isolation switch with program-

mable inrush current control. These devices also

integrate a voltage-mode PWM controller with two

power MOSFETs connected in a two-switch voltage-

clamped DC-DC converter configuration.

An integrated MOSFET provides PD isolation during

detection and classification. All devices guarantee a

leakage current offset of less than 10µA during the

detection phase. A programmable current limit pre-

vents high inrush current during power-on. The devices

feature power-mode undervoltage lockout (UVLO) with

wide hysteresis and long deglitch time to compensate

for twisted-pair-cable resistive drop and to assure

glitch-free transition between detection, classification,

and power-on/-off phases. The MAX5953A/MAX5953C

have an adjustable UVLO threshold with the default

value compliant to the 802.3af standard, while the

MAX5953B/MAX5953D have a lower and fixed UVLO

threshold compatible with some legacy pre-802.3af

power-sourcing equipment (PSE) devices.

The DC-DC converters are operable in either forward or

flyback configurations with a wide input voltage range

from 11V to 76V and up to 15W of output power. The

voltage-clamped power topology enables full recovery

of stored magnetizing and leakage inductive energy for

enhanced efficiency and reliability. When using the

high-side MOSFET, the controller can be configured as

a buck converter. A look-ahead signal for driving sec-

ondary-side synchronous rectifiers can be used to

increase efficiency. A wide array of protection features

include UVLO, over-temperature shutdown, and short-

circuit protection with hiccup current limit for enhanced

performance and reliability. Operation up to 500kHz

allows for smaller external magnetics and capacitors.

The MAX5953A/MAX5953B/MAX5953C/MAX5953D are

available in a high-power (2.22W), 7mm x 7mm ther-

mally enhanced thin QFN package.

19-3945; Rev 1; 7/06

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.

IEEE 802.3af PD Interface and PWM Controllers

IEEE 802.3af Powered

Devices

IP Phones

Wireless Access Nodes

________________________________________________________________ Maxim Integrated Products

General Description

Internet Appliances

Security Cameras

Computer Telephony

Applications

with Integrated Power MOSFETs

♦ Powered Device Interface

♦ DC-DC Converter

♦ High-Power (2.22W), 7mm x 7mm Thermally

Operating junction temperature range is 0°C to +125°C.

+Denotes lead-free package.

Pin Configuration and Typical Operating Circuit appear at

end of data sheet.

MAX5953AUTM+

MAX5953BUTM+

MAX5953CUTM+

MAX5953DUTM+

Enhanced Lead-Free Thin QFN Package

Fully Integrated IEEE 802.3af-Compliant PD

PD Detection and Programmable Classification

Less than 10µA Leakage Current Offset During

Integrated MOSFET for Isolation and Inrush

Gate Output Allows External Control of the

Programmable Inrush Current Control

Programmable Undervoltage Lockout

Clamped, Two-Switch Power IC for High

Integrated High-Voltage 0.4Ω Power MOSFETs

Bias Voltage Regulator with Automatic High-

11V to 76V Wide Input Voltage Range

Feed-Forward Voltage-Mode Control for Fast

Programmable Undervoltage Lockout

Overtemperature Shutdown

Indefinite Short-Circuit Protection with

Integrated Look-Ahead Signal for Secondary-

> 90% Efficiency with Synchronous

Up to 500kHz Switching Frequency

Interface

Signatures

Detection

Current Limiting

Internal Isolation MOSFET

(MAX5953A/MAX5953C)

Efficiency

Up to 15W Output Power

Voltage Supply Turn-Off

Input Transient Rejection

Programmable Fault Integration

Side Synchronous Rectification

Rectification

PART

Ordering Information

PIN-PACKAGE

48 TQFN

Features

PKG CODE

T4877-6

Related parts for MAX5953A

MAX5953A Summary of contents

Page 1

... The MAX5953A/MAX5953C have an adjustable UVLO threshold with the default value compliant to the 802.3af standard, while the MAX5953B/MAX5953D have a lower and fixed UVLO threshold compatible with some legacy pre-802 ...

Page 2

... Class 4, R RCLASS ( Measure at V+, not including GATE = V , HVIN = GND = OUT EE MAX5953A/MAX5953C V IN increasing MAX5953B/MAX5953D V decreasing, MAX5953A/MAX5953C IN ....................................................................500mA EE .........................................................70mA EE .....................................20mA EE ....................................................................80mA EE = +70° 0°C to +125°C, unless unless otherwise noted.) (Note 1) MIN TYP MAX 10 550 20 ...

Page 3

... PGOOD, PGOOD Output Low V Voltage PGOOD Leakage Current PGOOD Leakage Current _______________________________________________________________________________________ with Integrated Power MOSFETs = +25°C. All voltages are referenced CONDITIONS MAX5953A/MAX5953C MAX5953B/MAX5953D V MAX5953A/MAX5953C only (Note 7) IN,EX V increasing REF,UVLO UVLO Ratio to V REF, UVLO 2.460V IN,UVLO UVLO (Note 8) ...

Page 4

IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs ELECTRICAL CHARACTERISTICS (DC-DC Controller) (All voltages referenced to GND, unless otherwise noted. V 100pF 0.22µ 0V, V BST CSS +25°C, ...

Page 5

IEEE 802.3af PD Interface and PWM Controllers ELECTRICAL CHARACTERISTICS (DC-DC Controller) (continued) (All voltages referenced to GND, unless otherwise noted. V 100pF 0.22µ 0V, V BST CSS +25°C, unless otherwise noted.) ...

Page 6

... Note 9: An input voltage or V glitch below their respective thresholds shorter than or equal to t UVLO MAX5953A/MAX5953B/MAX5953C/MAX5953D to exit power-on mode (as long as the input voltage remains above an operable voltage level of 12V). Note 10: Guaranteed by design, not tested in production for MAX5953B/MAX5953D. Note 11: PGOOD references to OUT while PGOOD references to V ...

Page 7

... TEMPERATURE (°C) INRUSH CURRENT CONTROL (V = 48V) IN MAX5953A/B/C/D toc08 V GATE 5V/div V TO OUT V EE 50V/div I INRUSH 100mA/div PGOOD 50V/div 4ms/div , C EE INBIAS EFFECTIVE DIFFERENTIAL INPUT RESISTANCE vs. INPUT CURRENT 3 ...

Page 8

IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs ( 48V, GATE = PGOOD = unconnected, GND connected to OUT, HVIN connected to V+, UVLO = 2.2µF, ...

Page 9

IEEE 802.3af PD Interface and PWM Controllers ( 48V, GATE = PGOOD = unconnected, GND connected to OUT, HVIN connected to V+, UVLO = 2.2µ 25kΩ, C ...

Page 10

... N.C. 19, 35, 38, 46, 47 UVLO (MAX5953A/MAX5953C) 6 N.C. (MAX5953B/MAX5953D) 8 RCLASS 9 GATE 10 15, 16 OUT 18 PGOOD (MAX5953A/MAX5953B) 18 PGOOD (MAX5953C/MAX5953D PPWM 22 GND 23 PGND 24 CSS 10 ______________________________________________________________________________________ FUNCTION No Connection. Not internally connected. Make no electrical connection to these pins. Positive Input Power. Referenced Undervoltage Lockout Programming Input for PD Interface. UVLO is referenced to V When UVLO is above its threshold, the device enters the power mode ...

Page 11

IEEE 802.3af PD Interface and PWM Controllers PIN NAME 25 OPTO 26, 27 SRC 28, 29 XFRMRL 30 DRVIN 31, 32 XFRMRH 33, 34 DRNH 36 BST 37 DCUVLO 39 HVIN 40 INBIAS 41 REGOUT 42 RTCT 43 FLTINT 44 ...

Page 12

IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs POWER-OVER SIGNAL PAIRS RJ- POWER-OVER SPAIR PAIRS Figure 2. RJ-45 Connector, PoE Magnetic, and Input Diode Bridges 12 ______________________________________________________________________________________ Typical Application ...

Page 13

IEEE 802.3af PD Interface and PWM Controllers Figure 3. Typical Application Circuit ______________________________________________________________________________________ with Integrated Power MOSFETs 13 ...

Page 14

... IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs Figure 4. For higher power applications, the MAX5953A/MAX5953B/MAX5953C/MAX5953D can be used in a two-switch forward converter configuration 14 ______________________________________________________________________________________ ...

Page 15

... MAX5953A/MAX5953B/MAX5953C/MAX5953D input pins ( bridge voltage drop. ______________________________________________________________________________________ with Integrated Power MOSFETs Depending on the input voltage (V PD Interface front-end section of the MAX5953A/MAX5953B/ MAX5953C/MAX5953D operate in three different modes: PD detection signature, PD classification, and PD power. ...

Page 16

... Connect a 100kΩ pullup resistor from PGOOD needed. Thermal shutdown limits total power dissipation in the IC. If the junction temperature exceeds +160°C, ther- mal shutdown is enabled to turn off the MAX5953A/ MAX5953B/MAX5953C/MAX5953D, allowing the IC to cool. The IC turns on after the junction temperature cools by 20°C. ...

Page 17

... The Typical Application Circuit, Figure 3, shows the schematic diagram of a -48V input flyback converter using the MAX5953A. Figure 4 shows the schematic diagram of a -48V input forward converter and a 5V, 3A output isolated power supply. ...

Page 18

... IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs Program the MAX5953A/MAX5953B/MAX5953C/ MAX5953D soft-start with an external capacitor (C connected between CSS and GND. When the device turns on, C charges with a constant current of CSS 33µA, ramping up to 7.3V. During this time, the feed- ...

Page 19

IEEE 802.3af PD Interface and PWM Controllers Figure 6. PD with Three-Output Flyback DC-DC Converter ______________________________________________________________________________________ with Integrated Power MOSFETs 19 ...

Page 20

IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs Figure 7. PD with Nonisolated Step-Down (Buck) Converter 20 ______________________________________________________________________________________ ...

Page 21

IEEE 802.3af PD Interface and PWM Controllers Table 3. Component Suppliers COMPONENT Power FETS Current-Sense Resistors Diodes Capacitors Magnetics Layout Recommendations All connections carrying pulsed currents must be very short, as wide as possible, and have a ground plane as ...

Page 22

... IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs V+ UVLO REF V+ 21.8V 39V UVLO* 200mV GATE *MAX5953A/MAX5953C ONLY. **MAX5953C/MAX5953D ONLY. ***MAX5953A/MAX5953B ONLY. Figure 8. Powered Device Interface Block Diagram 22 ______________________________________________________________________________________ 2.4V REF MAX5953A 2.4V, 0.8 MAX5953B HYST MAX5953C MAX5953D GATE EN Q2 38Ω Block Diagrams 6 ...

Page 23

... FLTINT OVRLD 2.7V/1.9V RAMP CPWM OPTO 5V 33µA CSS 50Ω GND GND MAX5953A MAX5953B MAX5953C MAX5953D Figure 9. DC-DC Converter Block Diagram (Voltage-Mode PWM Controller and Two-Switch Power Stage) ______________________________________________________________________________________ with Integrated Power MOSFETs OVT REF REFOK (1.25V) DCUVLO DCUVLO 50Ω GND 80ns ...

Page 24

IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs 24 ______________________________________________________________________________________ Typical Operating Circuit ...

Page 25

... IEEE 802.3af PD Interface and PWM Controllers TOP VIEW DCUVLO N.C. HVIN INBIAS REGOUT RTCT FLTINT RCFF RAMP N.C. N.C. N.C. *UVLO FOR MAX5953A/MAX5953C N.C. FOR MAX5953B/MAX5953D ** PGOOD FOR MAX5953A/MAX5953B PGOOD FOR MAX5953C/MAX5953D Selector Guide PGOOD or PART PGOOD MAX5953A PGOOD MAX5953B PGOOD PGOOD MAX5953C PGOOD MAX5953D ______________________________________________________________________________________ with Integrated Power MOSFETs ...

Page 26

IEEE 802.3af PD Interface and PWM Controllers with Integrated Power MOSFETs (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) E E/2 D ...

Page 27

IEEE 802.3af PD Interface and PWM Controllers (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information www.maxim-ic.com/packages Revision History Pages changed at Rev Maxim ...

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