Rainbow Electronics MAX5074 User Manual

General Description

The MAX5074 isolated PWM power IC features integrated switching power MOSFETs connected in a voltageclamped, two-transistor, power-circuit configuration. This device can be used in both forward and 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. A lookahead signal for driving secondary-side synchronous rectifiers can be used to increase efficiency.

A wide array of protection features includes UVLO, overtemperature shutdown, and short-circuit protection with hiccup current limit for enhanced performance and reliability. Operation up to 500kHz allows smaller external magnetics and capacitors.

The MAX5074 is rated for operation over the -40°C to +125°C temperature range and is available in a 20-pin TSSOP package.

Warning: The MAX5074 is designed to work with high voltages. Exercise caution.

Applications

IEEE 802.3af PD Power Supplies

Isolated IP Phone Power Supplies

High-Efficiency Telecom/Datacom Power Supplies

48V Input, Isolated Power-Supply Modules

WLAN Access-Point Power Supplies

ADSL Line Cards

ADSL Line-Driver Power Supplies

Distributed Power Systems with 48V Bus

Features

♦ Clamped, Two-Switch Power IC for High Efficiency

♦ No Reset Winding Required

♦ Up to 15W Output Power

♦ Bias Voltage Regulator with Automatic High-

Voltage Supply Turn-Off

♦ 11V to 76V Wide Input Voltage Range ♦ Integrated High-Voltage 0.4Ω Power MOSFETs

♦ Feed-Forward Voltage-Mode Control For Fast

Input Transient Rejection

♦ Programmable Brownout Undervoltage Lockout

♦ Internal Overtemperature Shutdown

♦ Indefinite Short-Circuit Protection With

Programmable Fault Integration

♦ Integrated Look-Ahead Signal for Secondary-Side

Synchronous Rectification

♦ >90% Efficiency with Synchronous Rectification

♦ Up to 500kHz Switching Frequency

♦ High-Power (1.74W), Small-Footprint 20-Pin

Thermally Enhanced TSSOP Package

MAX5074

Power IC with Integrated MOSFETs for Isolated IEEE

802.3af PD and Telecom Power-Supply Applications

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

Ordering Information

MAX5074

DRNH

SRC

DRVL

DRVH

OUT

XFRMRH

XFRMRL

Simplified Application Circuit

19-3312; Rev 0; 7/04

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.

*EP = Exposed pad.

EVALUATION KIT AVAILABLE

INBIAS

HVIN

UVLO

BSTRCFF

MAX5074

TSSOP

DRNH

XFRMRH

DRVIN

XFRMRLPPWM

SRC

PGNDCS

TOP VIEW

REGOUT

RTCT

FLTINT

RAMP

OPTO

CSS

GND

PART TEMP RANGE PIN-PACKAGE

MAX5074AUP -40°C to +125°C 20-TSSOP-EP*

MAX5074

Power IC with Integrated MOSFETs for Isolated IEEE

802.3af PD and Telecom Power-Supply Applications

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

HVIN

= 12V, C

INBIAS

= 1µF, C

REGOUT

= 2.2µF, R

RTCT

= 25kΩ, C

RTCT

= 100pF, C

BST

= 0.22µF, V

CSS

= VCS= 0V, V

RAMP

= V

UVLO

= 3V,

= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C, unless otherwise noted.) (Note 1)

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.

HVIN, INBIAS, DRNH, XFRMRH,

XFRMRL to GND.................................................-0.3V to +80V

BST to GND ............................................................-0.3V to +95V

BST to XFRMRH .....................................................-0.3V to +12V

PGND to GND .......................................................-0.3V to +0.3V

UVLO, RAMP, CSS, OPTO, FLTINT, RCFF,

RTCT to GND......................................................-0.3V to +12V

SRC, CS to GND.......................................................-0.3V to +6V

REGOUT, DRVIN to GND .......................................-0.3V to +12V

REGOUT to HVIN ...................................................-80V to +0.3V

REGOUT to INBIAS ................................................-80V to +0.3V

REGOUT Current ................................................................50mA

PPWM to GND....................................-0.3V to (REGOUT + 0.3V)

PPWM Current .................................................................±20mA

DRNH, XFRMRH, XRFMRL, SRC Continuous Current (Average)

= +125°C......................................................................0.9A

= +150°C......................................................................0.6A

Continuous Power Dissipation (T

= +70°C)

20-Pin TSSOP-EP (derate 21.7mW/°C above +70°C) ....1.739W

20-Pin TSSOP-EP (θ

) ................................................46°C/W

Operating Temperature Range .........................-40°C to +125°C

Maximum Junction Temperature .....................................+150°C

Storage Temperature Range .............................-60°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Input Supply Range V

OSCILLATOR (RTCT)

PWM Frequency f

Maximum PWM Duty Cycle D

Maximum RTCT Frequency f

RTCT Peak Trip Level V

RTCT Valley Trip Level

RTCT Input Bias Current ±1 µA

RTCT Discharge MOSFET R

DS(ON)

RTCT Discharge Pulse Width 50 ns

LOOK-AHEAD LOGIC (PPWM)

PPWM to XFRMRL Output Propagation Delay

PPWM Output High V

PPWM Output Low V

PWM COMPARATOR (OPTO, RAMP, RCFF)

Common-Mode Range V

Input Offset Voltage 10 mV

Input Bias Current -2 +2 µA

RAMP to XFRMRL Propagation Delay

Minimum OPTO Voltage V

Minimum RCFF Voltage RCFF sinking 2mA 2.18 V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

HVIN

MAX

RTCTMAX

PPWM

CM-PWM

= 25kΩ, C

RTCT

= 25kΩ, C

RTCT

(Note 2) 1 MHz

Sinking 20mA 30 60 Ω

PPWM rising to XFRMRL falling 110 ns

Sourcing 2mA 7.0 11.0 V

Sinking 2mA 0.4 V

From RAMP (50mV overdrive) rising to XFRMRL rising

= 0V, OPTO sinking 2mA 1.47 V

CSS

RTCT

= 100pF 256 kHz

= 100pF 47 %

11 76 V

0.51 x

REGOUT

0.04 x

REGOUT

0 5.5 V

100 ns

MAX5074

Power IC with Integrated MOSFETs for Isolated IEEE

802.3af PD and Telecom Power-Supply Applications

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

HVIN

= 12V, C

INBIAS

= 1µF, C

REGOUT

= 2.2µF, R

RTCT

= 25kΩ, C

RTCT

= 100pF, C

BST

= 0.22µF, V

CSS

= VCS= 0V, V

RAMP

= V

UVLO

= 3V,

= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C, unless otherwise noted.) (Note 1)

)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

REGOUT LDO (REGOUT)

REGOUT Voltage Set Point V

REGOUT Load Regulation

REGOUT Dropout Voltage

REGOUT Undervoltage Lockout Threshold

REGOUT Undervoltage Lockout Threshold Hysteresis

SOFT-START (CSS)

Soft-Start Current I

INTEGRATING FAULT PROTECTION (FLTINT)

FLTINT Source Current I

FLTINT Trip Point FLTINT rising 2.7 V

FLTINT Hysteresis 0.8 V

INTERNAL POWER MOSFETs (See Figure 1, QH and QL)

On-Resistance R

Off-State Leakage Current -5 +5 µA

Total Gate Charge Per FET 15 nC

HIGH-SIDE DRIVER

Low-to-High Delay

High-to-Low Delay

Driver Output Voltage BST to XFRMRH with high side on 8 V

LOW-SIDE DRIVER

Low-to-High Delay

High-to-Low Delay

CURRENT-LIMIT COMPARATOR (CS)

Current-Limit Threshold Voltage V

Current-Limit Input Bias Current I

REGOUT

CSS

FLTINT

DS(ON

ILIM

BILIM

INBIAS floating, V

= V

INBIAS

INBIAS floating, V to 30mA

= V

INBIAS

30mA

INBIAS floating, I

= V

INBIAS

= 11V to 76V 8.3 9.2

HVIN

= 11V to 76V 9.5 11.0

HVIN

= 15V, I

HVIN

= 15V, I

HVIN

, I

REGOUT

= 30mA 1.25

REGOUT

= 30mA 1.25

REGOUT

= 0 to

= 0

0.25

REGOUT rising 6.6 7.4 V

REGOUT falling 0.7 V

33 µA

80 µA

= V

DRVIN

XFRMRH

Driver delay until FET V

- V

BST

Driver delay until FET V

- V

BST

Driver delay until FET V V

DRVIN

Driver delay until FET V V

DRVIN

= 9V,

BST

= V

= 0V, IDS = 50mA

SRC

) and is fully on

XFRMRH

) and is fully off

XFRMRH

and is fully on

and is fully off

reaches 0.9 x

reaches 0.1 x

reaches 0.9 x

reaches 0.1 x

0.4 0.8 Ω

80 ns

40 ns

80 ns

40 ns

140 156 172 mV

0 < VCS < 0.3V -2 +2 µA

MAX5074

Power IC with Integrated MOSFETs for Isolated IEEE

802.3af PD and Telecom Power-Supply Applications

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

HVIN

= 12V, C

INBIAS

= 1µF, C

REGOUT

= 2.2µF, R

RTCT

= 25kΩ, C

RTCT

= 100pF, C

BST

= 0.22µF, V

CSS

= VCS= 0V, V

RAMP

= V

UVLO

= 3V,

= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C, unless otherwise noted.) (Note 1)

Note 1: All limits at -40°C are guaranteed by design and not production tested. Note 2: Output switching frequency is half of oscillator frequency.

UNDERVOLTAGE LOCKOUT THRESHOLD

vs. TEMPERATURE

MAX5074 toc01

TEMPERATURE (°C)

UVLO

(V)

11095-25 -10 5 35 50 6520 80

1.2425

1.2450

1.2475

1.2500

1.2525

1.2550

1.2575

1.2600

1.2400

-40 125

UVLO RISING

STANDBY CURRENT vs. TEMPERATURE

MAX5074 toc02

TEMPERATURE (°C)

STANDBY CURRENT (µA)

1109565 80-10 5 20 35 50-25

105

140

175

210

245

280

315

350

-40 125

HVIN

UVLO =

HVIN INPUT CURRENT

vs. TEMPERATURE

MAX5074 toc03

TEMPERATURE (°C)

HVIN

(mA)

11095-25 -10 5 35 50 6520 80

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.0

-40 125

HVIN

= 76V INBIAS FLOATING REGOUT = DRVIN

Typical Operating Characteristics

HVIN

= 48V, V

INBIAS

= 15V, C

INBIAS

= 1µF, C

REGOUT

= 2.2µF, R

RTCT

= 25kΩ, C

RTCT

= 100pF, C

BST

= 0.22µF, V

CSS

= VCS= 0V,

RAMP

= V

UVLO

= 3V, TA = TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Propagation Delay to XFRMRL t

BOOST VOLTAGE CIRCUIT (See Figure 1, QB)

Driver Output Delay t

One-Shot Pulse Width t

QB R

DS(ON)

THERMAL SHUTDOWN

Shutdown Temperature T

Thermal Hysteresis T

UNDERVOLTAGE LOCKOUT (UVLO)

UVLO Threshold V

UVLO Hysteresis V

UVLO Input Bias Current I

SUPPLY CURRENT

Supply Current

Standby Supply Current V

dILIM

PPWMD

PWQB

HYST

UVLO

HYST

BUVLO

From CS rising (10mV overdrive) to XFRMRL rising

160 ns

200 ns

300 ns

Sinking 20mA 30 60 Ω

Temperature rising +160 °C

15 °C

rising 1.14 1.38 V

UVLO

140 mV

= 3V -100 +100 nA

UVLO

From V V

INBIAS

From V V

HVIN

From V

UVLO

= 11V to 76V, V

HVIN

= 11V

= 11V to 76V, V

INBIAS

= 76V

= 76V 7

HVIN

CSS

= 0V,

0.7 2

4.4 6.0

= 0V 1 mA

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Rainbow Electronics MAX5074 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual