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MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer

Driver for Isolated Power Supplies

General Description

The MAX13253 is a 1A, push-pull, transformer driver

designed to provide a simple solution for low-EMI isolated

power supplies. The MAX13253 has an internal oscillator

and operates from a single +3.0V to +5.5V supply. The

transformer’s secondary-to-primary winding ratio defines

the output voltage, allowing selection of virtually any iso-

lated output voltage with galvanic isolation.

The MAX13253 features an integrated oscillator driving

a pair of n-channel power switches. The driver includes

pin-selectable spread-spectrum oscillation and a well-

controlled slew rate to reduce EMI. The MAX13253 can

optionally be driven by an external clock to further man-

age EMI. Internal circuitry guarantees a fixed 50% duty

cycle to prevent DC current flow through the transformer,

regardless of which clock source is used.

The MAX13253 operates with up to 1A of continuous

current and features integrated protection including fault

detection, overcurrent protection, and thermal shutdown.

The MAX13253 includes a low-current shutdown mode to

reduce the overall supply current to less than 5µA (max)

when the driver is disabled.

The MAX13253 is available in a small 10-pin (3mm x

3mm) TDFN package and is specified over the -40°C to

+125°C temperature range.

Features and Benets

● Simple, Flexible Design

• +3.0V to +5.5V Supply Range

• Low R

300mΩ(max)at4.5V

• Up to 90% Efficiency

• Provides Up to 1A to the Transformer

• Internal or External Clock Source

• Internal Oscillator Frequency: 250kHz or 600kHz

• Optional Spread-Spectrum Oscillation

• -40ºC to +125ºC Temperature Range

● Integrated System Protection

• Fault Detection and Indication

• Overcurrent Limiting

• Undervoltage Lockout

• Thermal Shutdown

● Saves Space on Board

• Small 10-Pin TDFN Package (3mm x 3mm)

Applications

● PowerMeterDataInterface

● IsolatedFieldbusInterface

● MedicalEquipment

● IsolatedAnalogFront-End

● IsolatedUSBPower

19-6600; Rev 1; 4/13

Ordering Information appears at end of data sheet.

For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX13253.related.

Typical Operating Circuit

EVALUATION KIT AVAILABLE

FAULT

1µF

10µF

CLK

SPRD

HICLK

GND

PGND

ISOLATED

OUT

1CT:1.3CT

MAX13253

Summary of content (14 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies General Description The MAX13253 is a 1A, push-pull, transformer driver designed to provide a simple solution for low-EMI isolated power supplies. The MAX13253 has an internal oscillator and operates from a single +3.0V to +5.5V supply.
PAGE 2
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Absolute Maximum Ratings TDFN (Single-Layer Board) (derate 18.5mW/ºC above +70ºC)...........................1481.5mW Operating Temperature Range...........................-40ºC to +125ºC Junction Temperature....................................................... +150ºC Storage Temperature Range..............................-65ºC to +150°C Lead Temperature (soldering, 10s)..................................
PAGE 3
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Electrical Characteristics (continued) (VDD = +3.0V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VDD = +5.0V and TA = +25ºC.) (Note 2) PARAMETER SYMBOL LOGIC SIGNALS (CLK, EN, HICLK, SPRD, FAULT) CONDITIONS MIN TYP MAX 2 Input Logic-High Voltage VIH Input Logic-Low Voltage VIL Input Leakage Current IIL EN, CLK, SPRD, HICLK = 0V or 5.
PAGE 4
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies IF SPRD = GND (DITHER AMOUNT = 0%) +4% of fSW 8% DITHER AMOUNT fSW -4% of fSW 1 fMOD TIME Figure 1. Frequency Spread Timing Diagram VDD 100I T1, T2 50pF 2 x VDD T1 0V 2 x VDD tDEAD tDEAD T2 0V Figure 2. T1, T2 Timing Diagram www.maximintegrated.
PAGE 5
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Typical Operating Characteristics (VDD = +5V, TA = +25°C, unless otherwise noted.) 2.0 1.5 1.0 0.5 510 CLK = GND SPRD = GND 460 410 360 310 210 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 -45 EXTERNAL CLOCK FREQUENCY (MHz) 0.14 VDD = 3.3V 0.12 0.10 VDD = 5V 0.08 0.06 0.04 0.02 0.2 0.4 55 80 105 0.6 0.8 MAX13253 toc03 30 MAX13253 toc06 0 0.2 0.4 LOAD CURRENT (A) www.maximintegrated.com 0.6 0.
PAGE 6
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Typical Operating Characteristics (continued) (VDD = +5V, TA = +25°C, unless otherwise noted.) TA = +85°C 84 TA = +125°C CLK = GND HICLK = GND SPRD = GND 1:1:1.3:1.3 HALO TGM-H240V8LF TRANSFORMER 82 80 78 0 85 HICLK = VDD 80 CLK = GND SPRD = GND 1:1:1.3:1.3 HALO TGM-H240V8LF TRANSFORMER 75 70 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.
PAGE 7
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Pin Configuration TOP VIEW T1 10 PGND T2 9 GND FAULT 8 7 6 MAX13253 *EP + 1 VDD 2 3 4 CLK HICLK EN 5 SPRD TDFN *EXPOSED PAD—CONNECT TO GND Pin Description PIN NAME 1 VDD Power-Supply Input. Bypass VDD to GND with a 1µF capacitor as close as possible to the device. 2 CLK Clock Input. Connect CLK to GND to enable internal clocking. Apply a clock signal to CLK to enable external clocking.
PAGE 8
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Functional Diagram VDD MAX13253 UVLO HICLK SPRD T1 VUVLO OSC 10µA CLK EN MUX FLIPFLOP DRIVER T2 WATCHDOG FAULT CURRENT LIMIT GND Detailed Description The MAX13253 is an integrated primary-side transformer driver for low-EMI isolated power-supply circuits.
PAGE 9
MAX13253 T1 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies 1CT: nCT + - VIN VOUT = nVIN - VD T2 VD = DIODE FORWARD VOLTAGE 1CT: nCT + VIN VOUT = 2(nVIN - VD) - T2 (B) VOLTAGE DOUBLER 1CT: nCT VIN + VOUT = nVIN - 2VD T2 VD = DIODE FORWARD VOLTAGE (C) FULL-WAVE RECTIFIER Figure 3. Secondary-Side Rectification Topologies SPRD input low or leave unconnected to disable spread spectrum on the internal oscillator. SPRD has an internal 10µA pulldown to ground.
PAGE 10
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Applications Information Output Voltage Regulation Power Dissipation The power dissipation of the device is approximated by: PD = (RO x IPRI2) + (IDD x VDD) where RO is the resistance of the internal FET drivers and IPRI is the load current flowing into T1 and T2. Ensure that the power dissipation of the MAX13253 is kept below the Absolute Maximum Ratings for proper operation.
PAGE 11
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies 3.3V 1µF HICLK VDD 1CT:2CT T2 IN SPRD 1µF FAULT MAX13253 GND PGND FB 4.7µF MAX8881 10µF EN CLK OUT SHDN 5V ISO OUTPUT GND T1 Figure 5. 3.3V to Isolated, Regulated 5V Application Circuit Isolated USB/RS-485/RS-232 Isolated Applications Exposed Pad The MAX13253 can provide isolated power for USB/ RS-485/RS-232 applications.
PAGE 12
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies For example, when the internal oscillator is used to drive the outputs and HICLK is low, the required transformer ET product to the center tap for an application with VDD (max) = 5.5V, is 13.1V-µs. An application with VDD (max) = 3.3V has a transformer ET product to the center tap requirement of 7.9V-µs.
PAGE 13
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Package Information Ordering Information PART TEMP RANGE PIN-PACKAGE MAX13253ATB+ -40°C to +125°C 10 TDFN-EP* +Denotes lead(Pb)-free/RoHS-compliant package. *EP = Exposed Pad Chip Information PROCESS: BiCMOS www.maximintegrated.com For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages.
PAGE 14
MAX13253 1A, Spread-Spectrum, Push-Pull, Transformer Driver for Isolated Power Supplies Revision History REVISION NUMBER REVISION DATE PAGES CHANGED 0 3/13 Initial release 1 4/13 Updated TOC parameters, updated Figure 4, replaced Figure 5, updated Output Voltage Regulation section DESCRIPTION — 5, 6, 10, 11 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.