MAX5941BCSE-T Maxim Integrated, MAX5941BCSE-T Datasheet

MAX5941BCSE-T

Manufacturer Part Number

MAX5941BCSE-T

Description

Power Switch ICs - POE / LAN

Manufacturer

Maxim Integrated

Datasheet

1.MAX5941AESE-T.pdf (24 pages)

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The MAX5941A/MAX5941B integrate a complete power

IC for powered devices (PD) in a power-over-ethernet

(PoE) system. The MAX5941A/MAX5941B provide a PD

interface and a compact DC-DC PWM controller suitable

for flyback and forward converters in either isolated or

nonisolated designs.

The MAX5941A/MAX5941B PD interface complies with

the IEEE 802.3af standard, providing the PD with a detec-

tion signature, a classification signature, and an integrat-

ed isolation switch with programmable inrush current

control. These devices also feature power-mode under-

voltage lockout (UVLO) with wide hysteresis and power-

good status outputs.

The MAX5941A/MAX5941B also integrate all the building

blocks necessary for implementing DC-DC fixed-

frequency isolated power supplies. These devices are a

current-mode controller with an integrated high startup

circuit suitable for isolated telecom/industrial voltage-

range power supplies. A high-voltage startup circuit

allows the PWM controller to draw power directly from the

18V to 67V input supply during startup. The switching fre-

quency is internally trimmed to 275kHz ±10%, thus

reducing magnetics and filter components. The

MAX5941A allows an 85% operating duty cycle and can

be used to implement flyback converters. The MAX5941B

limits the operating duty cycle to less than 50% and can

be used in single-ended forward converters. The

MAX5941A/MAX5941B are designed to work with or with-

out an external diode bridge in front of the PD.

The MAX5941A/MAX5941B are available in 16-pin SO

packages.

19-3069; Rev 4; 6/06

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.

Typical Operating Circuit appears at end of data sheet.

IP Phones

Wireless Access Nodes

Internet Appliances

Computer Telephony

Security Cameras

Power Devices in Power-Over-Ethernet/

Power-Over-MDI

IEEE 802.3af-Compliant Power-Over-Ethernet

Interface/PWM Controller for Power Devices

________________________________________________________________ Maxim Integrated Products

General Description

Applications

o Powered Device Interface

o PWM Controller

MAX5941AESE -40°C to +85°C 16 SO (S16M-6)

MAX5941ACSE

MAX5941BESE -40°C to +85°C 16 SO (S16M-6)

MAX5941BCSE

Fully Integrated IEEE 802.3af-Compliant PD

Interface

PD Detection and Programmable Classification

Signatures

Less than 10µA Leakage Current Offset During

Detection

Integrated MOSFET for Isolation and Inrush

Current Limiting

Gate Output Allows External Control of the

Internal Isolation FET

Programmable Inrush Current Control

Programmable Undervoltage Lockout

Wide Input Range: 18V to 67V

Current-Mode Control

Leading-Edge Blanking

Internally Trimmed 275kHz ±10% Oscillator

Soft-Start

PART

TOP VIEW

SS_SHDN

OPTO

ULVO

GATE

RCL

TEMP RANGE

V+

0°C to +70°C 16 SO (S16M-6)

Ordering Information

MAX5941A

MAX5941B

Pin Configuration

PIN-

PACKAGE

NDRV

V-

GND

PGOOD

OUT

Features

M A X D U T Y

C YC L E ( % )

Related parts for MAX5941BCSE-T

MAX5941BCSE-T Summary of contents

Page 1

... Current-Mode Control Leading-Edge Blanking Internally Trimmed 275kHz ±10% Oscillator Soft-Start PART MAX5941AESE -40°C to +85° (S16M-6) MAX5941ACSE MAX5941BESE -40°C to +85° (S16M-6) Applications MAX5941BCSE TOP VIEW Features Ordering Information PIN TEMP RANGE PACKAGE 0° ...

Page 2

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices ABSOLUTE MAXIMUM RATINGS (All voltages are referenced unless otherwise noted.) EE GND........................................................................-0.3V to +90V OUT, PGOOD ...........................................-0.3V to (GND + 0.3V) RCL, GATE .............................................................-0.3V to +12V UVLO ........................................................................-0.3V to ...

Page 3

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices ELECTRICAL CHARACTERISTICS (continued 48V, GATE = PGOOD = PGOOD = OPEN, V- tied to OUT, V+ tied to GND, UVLO = (GND - unless ...

Page 4

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices ELECTRICAL CHARACTERISTICS (PWM Controller) (continued) (All voltages referenced to V 13V, a 10µF capacitor connects V DD SS_SHDN, NDRV = open circuit, OPTO = V-, T PARAMETER SYMBOL V+ Shutdown ...

Page 5

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices Note 1: All min/max limits for the PD interface are production tested at +85°C (extended grade)/+70°C (commercial grade). Limits at +25°C and -40°C are guaranteed by design. All PWM controller min/max limits ...

Page 6

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices ) = 48V, GATE = PGOOD = PGOOD = OUT = OPEN, UVLO = (GND - Typical values are +25°C. All voltages are ...

Page 7

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices ) = 48V, GATE = PGOOD = PGOOD = OUT = OPEN, UVLO = (GND - Typical values are +25°C. All voltages are ...

Page 8

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices ) = 48V, GATE = PGOOD = PGOOD = OUT = OPEN, UVLO = (GND - Typical values are +25°C. All voltages are ...

Page 9

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices ) = 48V, GATE = PGOOD = PGOOD = OUT = OPEN, UVLO = (GND - Typical values are +25°C. All voltages are ...

Page 10

... EE OUT impedance. 12 GND Ground. Referenced to V Current-Sense Input. Referenced to V-. Turns power switch off current limiting also the feedback for the current-mode controller. CS connects to the PWM controller through a leading-edge blanking circuit the ground terminal of the PWM Controller. Connect to OUT. ...

Page 11

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices Table 1. PD Power Classification/R CLASS USAGE 0 Default 1 Optional 2 Optional 3 Optional 4 Not allowed *Class 4 reserved for future use. Detailed Description The MAX5941A/MAX5941B integrate a complete power ...

Page 12

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices Table 2. Setting Classification Current CLASS R (Ω ( 10k 12 732 12 392 12 255 12.6 to ...

Page 13

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices The PSE determines the class applying a volt- age at the PD input and measures the current sourced out of the PSE. When the PSE applies a voltage ...

Page 14

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices Thermal Dissipation During classification mode, if the PSE applies the maxi- mum DC voltage, the maximum voltage drop from GND to V will be 13V. If the maximum classification current RCL of ...

Page 15

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices HIGH- VOLTAGE V- REGULATOR EN OUT MAX5941A ONLY SLOPE COMPENSATION 26mV/µs 26mV/µs ∑ OPTO SS_SHDN 2.4V 0.4V Figure 4. MAX5941A/MAX5941B PWM Controller Functional Diagram ______________________________________________________________________________________ IN BIAS WINDING ...

Page 16

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices 1N4148 V IN (30V TO 72V 47µF UVLO RCL R DISC GATE 25.5kΩ PGOOD R CL SS_SHDN C SS 0.1µF PGOOD V EE Figure 5. Forward Converter to ...

Page 17

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices R DISC 25.5kΩ Figure 6. Flyback Converter PWM Comparator and Slope Compensation An internal 275kHz oscillator determines the switching frequency of the controller. At the beginning of each cycle, NDRV ...

Page 18

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices × × SENSE OUT × where and N and N S turns on the secondary and primary side of ...

Page 19

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices 4) The reset winding turns ratio (N low enough to guarantee that the entire energy in the transformer is returned to V+ within the off cycle at the maximum duty cycle. Use ...

Page 20

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices Table 3. Component Suppliers COMPONENT Power FETS Current-Sense Resistors Diodes Capacitors Magnetics where the combined RMS output ripple due to RIPPLE V , the ESR ripple, and V RIPPLE,ESR capacitive ...

Page 21

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices SIGNAL PAIRS RJ- POWER OVER SPARE PAIRS GND R1** R DISC 25.5kΩ 68nF 60V R2** RCL -48V *OPTIONAL. **R1 AND R2 ARE OPTIONAL AND ...

Page 22

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices POWER-SUPPLY CIRCUIT 1 GND R DISC 25.5kΩ 60V 68nF -48V POWER-SUPPLY CIRCUIT 2 *OPTIONAL AND R2 ARE OPTIONAL AND WHEN USED, THEY MUST TOTAL TO 25.5kΩ AND REPLACE THE 25.5kΩ ...

Page 23

IEEE 802.3af-Compliant Power-Over-Ethernet Interface/PWM Controller for Power Devices GND R DISC 25.5kΩ 60V -48V ______________________________________________________________________________________ V+ GND NDRV MAX5941A MAX5941B SS_SHDN PGOOD V PGOOD UVLO RCL GATE OPTO OUT GATE TRANSISTOR ...

Page 24

... 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. 24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products DIM ...

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