Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - DC/DC voltage regulator Holder SOIC 8

V =3.3V

0 0.5

I -OutputCurrent- A

100

Efficiency-%

V =8V

V =12V

V =18V

0.25 0.75 1 1.25 1.5 1.75 2

V =15V

VIN

GND

BOOT

VSENSE

COMP

VIN

VOUT

TPS54233

BOOT

Ren1

Ren2

TPS54233

www.ti.com

SLUS859B –OCTOBER 2008– REVISED FEBRUARY 2011

2A, 28V INPUT, STEP DOWN SWIFT™ DC/DC CONVERTER WITH ECO-MODE™

Check for Samples: TPS54233

FEATURES

APPLICATIONS

• Consumer Applications such as Set-Top

• 3.5 V to 28 V Input Voltage Range

Boxes, CPE Equipment, LCD Displays,

• Adjustable Output Voltage Down to 0.8 V

Peripherals, and Battery Chargers

• Integrated 80 mΩ High Side MOSFET Supports

• Industrial and Car Audio Power Supplies

up to 2A Continuous Output Current

• 5V, 12V and 24V Distributed Power Systems

• High Efficiency at Light Loads with a Pulse

Skipping Eco-mode™

DESCRIPTION

• Fixed 300 kHz Switching Frequency

The TPS54233 is a 28 V, 2 A non-synchronous buck

• Typical 1 μA Shutdown Quiescent Current

converter that integrates a low R

DS(on)

high side

• Adjustable Slow Start Limits Inrush Currents

MOSFET. To increase efficiency at light loads, a

pulse skipping Eco-mode™ feature is automatically

• Programmable UVLO Threshold

activated. Furthermore, the 1 μA shutdown supply

• Overvoltage Transient Protection

current allows the device to be used in battery

• Cycle by Cycle Current Limit, Frequency Fold

powered applications. Current mode control with

Back and Thermal Shutdown Protection

internal slope compensation simplifies the external

compensation calculations and reduces component

• Available in Easy-to-Use SOIC8 Package

count while allowing the use of ceramic output

• Supported by SwitcherPro™ Software Tool

capacitors. A resistor divider programs the Hysteresis

(http://focus.ti.com/docs/toolsw/folders/print/s

of the input under-voltage lockout. An overvoltage

witcherpro.html)

transient protection circuit limits voltage overshoots

during startup and transient conditions. A cycle by

• For SWIFT™ Documentation, See the TI

cycle current limit scheme, frequency fold back and

Website at www.ti.com/swift

thermal shutdown protect the device and the load in

the event of an overload condition. The TPS54233 is

available in an 8-pin SOIC package that has been

internally optimized to improve thermal performance.

SIMPLIFIED SCHEMATIC EFFICIENCY

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas

Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2SWIFT, Eco-mode, SwitcherPro, PowerPAD are trademarks of Texas Instruments.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (25 pages)

PAGE 1
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com 2A, 28V INPUT, STEP DOWN SWIFT™ DC/DC CONVERTER WITH ECO-MODE™ Check for Samples: TPS54233 FEATURES APPLICATIONS • • • • 1 2 • • • • • • • • • • 3.5 V to 28 V Input Voltage Range Adjustable Output Voltage Down to 0.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. DESCRIPTION CONTINUED For additional design needs, see: TPS54231 TPS54232 TPS54233 TPS54331 TPS54332 IO(Max) 2A 2A 2A 3A 3.5A Input Voltage Range 3.5V - 28V 3.5V - 28V 3.5V - 28V 3.5V - 28V 3.5V - 28V Switching Freq.
PAGE 3
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com PACKAGE DISSIPATION RATINGS (1) (1) (2) (3) (2) (3) PACKAGE THERMAL IMPEDANCE JUNCTION TO AMBIENT PSEUDO THERMAL IMPEDANCE JUNCTION TO TOP SOIC8 100°C/W 5°C/W Maximum power dissipation may be limited by overcurrent protection Power rating at a specific ambient temperature TA should be determined with a junction temperature of 150°C. This is the point where distortion starts to substantially increase.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com ELECTRICAL CHARACTERISTICS (continued) TJ = –40°C to 150°C, VIN = 3.5V to 28V (unless otherwise noted) DESCRIPTION TEST CONDITIONS MIN TYP MAX UNIT THERMAL SHUTDOWN Thermal Shutdown 165 °C SLOW START (SS PIN) Charge current V(SS) = 0.4 V 2 μA SS to VSENSE matching V(SS) = 0.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com FUNCTIONAL BLOCK DIAGRAM EN VIN 165 C Thermal Shutdown 1 mA 3 mA Shutdown Shutdown Logic 1.25 V Enable Threshold Enable Comparator Boot Charge ™ ECO-MODE Minimum Clamp Boot UVLO BOOT 2.1V Error Amplifier VSENSE 2 mA PWM Comparator Gate Drive Logic gm = 92 mA/V DC gain = 800 V/V BW = 2.7 MHz Voltage Reference SS 2 kW 0.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) MINIMUM CONTROLLABLE ON TIME vs JUNCTION TEMPERATURE VOLTAGE REFERENCE vs JUNCTION TEMPERATURE 0.8240 4 0.8120 0.8060 0.8000 0.7940 0.7880 0.7820 0.7760 -50 -25 0 25 50 75 100 TJ - Junction Temperature - °C 125 130 120 110 100 -50 150 VIN = 12 V VIN = 12 V Minimum Controllable Duty Ratio - % Tonmin - Minimum Controllable On Time - ns 140 0.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) OVERVIEW The TPS54233 is a 28 V, 2 A, step-down (buck) converter with an integrated high-side n-channel MOSFET. To improve performance during line and load transients, the device implements a constant frequency, current mode control which reduces output capacitance and simplifies external frequency compensation design. The TPS54233 has a pre-set switching frequency of 300 kHz.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com ENABLE AND ADJUSTABLE INPUT UNDER-VOLTAGE LOCKOUT (VIN UVLO) The EN pin has an internal pull-up current source that provides the default condition of the TPS54233 operating when the EN pin floats. The TPS54233 is disabled when the VIN pin voltage falls below internal VIN UVLO threshold. It is recommended to use an external VIN UVLO to add Hysteresis unless VIN is greater than (VOUT + 2V).
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com CURRENT MODE COMPENSATION DESIGN To simplify design efforts using the TPS54233, the typical designs for common applications are listed in Table 1. For designs using ceramic output capacitors, proper derating of ceramic output capacitance is recommended when doing the stability analysis. This is because the actual ceramic capacitance drops considerably from the nominal value when the applied voltage increases.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com R6 3.24 kW R5 30.9 kW R2 68.1 kW C1 10 mF Vin 8 - 18 V R1 332 kW C4 0.1 mF C5 0.015 mF B230A D1 C6 220 pF L1 15 mH + C7 220 pF C9 470 mF R5 10.2 kW Vout 3.3 V, Iout Max 2 A APPLICATION INFORMATION Figure 12.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com STEP BY STEP DESIGN PROCEDURE The following design procedure can be used to select component values for the TPS54233. Alternately, the SwitcherPro™Software may be used to generate a complete design. The SwitcherPro™ Software uses an iterative design procedure and accesses a comprehensive database of components when generating a design. This section presents a simplified discussion of the design process.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com This input ripple voltage can be approximated by Equation 6 IOUT(MAX) ´ 0.25 DVIN = + IOUT(MAX) ´ ESRMAX CBULK ´ fSW ( ) (6) Where IOUT(MAX) is the maximum load current, fSW is the switching frequency, CBULK is the bulk capacitor value and ESRMAX is the maximum series resistance of the bulk capacitor. The maximum RMS ripple current also needs to be checked.
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TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com Capacitor Selection The important design factors for the output capacitor are dc voltage rating, ripple current rating, and equivalent series resistance (ESR). The dc voltage and ripple current ratings cannot be exceeded. The ESR is important because along with the inductor current it determines the amount of output ripple voltage. The actual value of the output capacitor is not critical, but some practical limits do exist.
PAGE 14
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com The dc gain is determined by Equation 15: Vggm ´ VREF GDC = VO (15) Where: Vggm = 800 VREF = 0.8 V The low-frequency pole is determined by Equation 16: VPO = 1/ (2 ´ p ´ ROO ´ CZ ) (16) The mid-frequency zero is determined by Equation 17: FZ1 = 1/ (2 ´ p ´ R Z ´ CZ ) (17) And, the mid-frequency pole is given by Equation 18: FP1 = 1/ (2 ´ p ´ R Z ´ CP ) (18) The first step is to choose the closed loop crossover frequency.
PAGE 15
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com FP1 = FCO ´ k (24) The low-frequency pole is set so that the gain at the crossover frequency is equal to the inverse of the gain of the modulator and output filter. Due to the relationships established by the pole and zero relationships, the value of RZ can be derived directly by Equation 25 : RZ = VO ´ ROA ´ 0.98 GMCOMP ´ Vggm ´ VREF ´ RESR (25) Where: VO = Output voltage ROA = 8.696 MΩ GMCOMP = 9 A/V Vggm = 800 VREF = 0.
PAGE 16
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com C7 = 220 pF The measured overall loop response for the circuit is given in Figure 12. Note that the actual closed loop crossover frequency is higher than intended at about 25 kHz. This is primarily due to variation in the actual values of the output filter components and tolerance variation of the internal feed-forward gain circuitry.
PAGE 17
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com The device power dissipation includes: 1) Conduction loss: Pcon = Iout2 x RDS(on) x VOUT/VIN 2) Switching loss: Psw = 0.5 x 10-9 x VIN2 x IOUT x Fsw 3) Gate charge loss: Pgc = 22.8 x 10-9 x Fsw 4) Quiescent current loss: Pq = 0.075 x 10-3 x VIN Where: IOUT is the output current (A). RDS(on) is the on-resistance of the high-side MOSFET (Ω). VOUT is the output voltage (V). VIN is the input voltage (V). Fsw is the switching frequency (Hz).
PAGE 18
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com OUTPUT FILTER CAPACITOR TOPSIDE GROUND AREA Route BOOT CAPACITOR trace on other layer to provide wide path for topside ground Vout Feedback Trace OUTPUT INDUCTOR CATCH DIODE PH INPUT BYPASS CAPACITOR BOOT Vin UVLO RESISTOR DIVIDER VIN GND EN COMP SS VSENSE SLOW START CAPACITOR Thermal VIA BOOT CAPACITOR PH COMPENSATION NETWORK RESISTOR DIVIDER Signal VIA Figure 13.
PAGE 19
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com APPLICATION CURVES 100 100 VO = 3.3 V 95 VIN = 8 V VIN = 12 V 95 VIN = 15 V VIN = 8 V 90 VIN = 12 V VIN = 15 V 90 Efficiency - % Efficiency - % 85 85 VIN = 18 V 80 75 80 75 VIN = 18 V 70 65 70 60 65 55 50 60 0 0.25 1 1.25 1.5 0.5 0.75 IO - Output Current - A 1.75 0 2 Figure 14. TPS54233 Efficiency 40 60 80 100 120 140 160 180 200 IO - Output Current - mA Figure 15. TPS54233 Low Current Efficiency 0.05 0.
PAGE 20
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com 180 60 Gain Phase VOUT IOUT -180 -60 10 1M f - Frequency - Hz Figure 18. TPS54233 Transient Response Figure 19. TPS54233 Loop Response VOUT VIN PH PH Figure 20. TPS54233 Input Ripple 20 Figure 21.
PAGE 21
TPS54233 SLUS859B – OCTOBER 2008 – REVISED FEBRUARY 2011 www.ti.com VIN ENA VOUT VOUT Figure 22. TPS54233 Start Up Figure 23. TPS54233 Start-up Relative to Enable VOUT PH Figure 24. TPS54233 Eco-mode™ Operation space REVISION HISTORY Changes from Original (October 2008) to Revision A Page • Added a new table to the Description - For additional design needs ...................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46C and to discontinue any product or service per JESD48B. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.