TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 DUAL SYNCHRONOUS STEP-DOWN CONTROLLER FOR LOW VOLTAGE POWER RAILS Check for Samples: TPS53125 FEATURES APPLICATIONS • • 1 2 • • • • • • • • • • • • D-CAP2™ Mode Control – Fast Transient Response – No External Parts Required for Loop Compensation – Compatible With Ceramic Output Capacitors High Initial Reference Accuracy (±1%) Low Output Ripple Wide Input Voltage Range:4.5 V to 24 V Output Voltage Range: 0.76 V to 5.5 V Low-Side RDS(ON) Loss-Less Current Sensing Adaptive Gate Drivers with Integrated Boost Diode Adjustable Soft Start Non-Sinking Pre-Biased Soft Start 350-kHz Switching Frequency Cycle-by-Cycle Over-Current Limiting Control 30-mV to 300-mV OCP Threshold Voltage Thermally Compensated OCP by 4000 ppm/°C at ITRIP Point-of-Load Regulation in Low Power Systems for Wide Range of Applications – Digital TV Power Supply – Networking Home Terminal – Digital Set-Top Box (STB) – DVD Player/Recorder – Gaming Consoles DESCRIPTION The TPS53125 is a dual, adaptive on-time D-CAP2™ mode synchronous buck controller. The part enables system designers to cost effectively complete the suite of various end equipment's power bus regulators with a low external component count and low standby consumption. The main control loop for the TPS53125 uses the D-CAP2™ Mode topology which provides a very fast transient response with no external component. The TPS53125/7 also has a proprietary circuit that enables the device to adapt not only low equivalent series resistance (ESR) output capacitors such as POSCAP/SP-CAP, but also ceramic capacitor. The part provides a convenient and efficient operation with conversion voltages from 4.5 V to 24 V and output voltage from 0.76 V to 5.5 V. The TPS53125 is available in the 24 pin RGE/PW package, and is specified from –40°C to 85°C ambient temperature range. 1 2 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. D-CAP2 is a trademark 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. Copyright © 2009, Texas Instruments Incorporated TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com TYPICAL APPLICATION CIRCUITS Figure 1. QFN Figure 2. TSSOP 2 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 ORDERING INFORMATION (1) TA PACKAGE ORDERING PART NUMBER (2) (3) TSSOP ECO PLAN Tape-and-Reel TPS53125RGER (Preview) –40°C to 85°C (2) (3) OUTPUT SUPPLY TPS53125RGET (Preview) Plastic Quad Flat Pack (QFN) (1) PINS 24 Green (RoHS and no Sb/Br) Tape-and-Reel TPS53125PWR Tape-and-Reel TPS53125PW Tube For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com. Package drawings, thermal data, and symbolization are available at www.ti.com/packaging. All packaging options have Cu NIPDAU lead/ball finish. ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range (unless otherwise noted) (1) VALUE VI Input voltage range VO Output voltage range UNIT VIN, EN1, EN2 –0.3 to 26 VBST1, VBST2 –0.3 to 32 VBST1 - SW1, VBST2 - SW2 –0.3 to 6 V5FILT, VFB1, VFB2, TRIP1, TRIP2, VO1, VO2 –0.3 to 6 SW1, SW2 –2 to 26 DRVH1, DRVH2 –1 to 32 DRVH1 - SW1, DRVH2 - SW2 –0.3 to 6 DRVL1, DRVL2, VREG5, SS1, SS2 –0.3 to 6 PGND1, PGND2 V V –0.3 to 0.3 TA Operating ambient temperature range –40 to 85 °C TSTG Storage temperature range –55 to 150 °C TJ Junction temperature range –40 to 150 °C (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 under "recommended operating conditions" are not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. DISSIPATION RATINGS 2-oz. trace and copper pad with solder TA < 25°C POWER RATING DERATING FACTOR ABOVE TA = 25°C TA = 85°C POWER RATING 24-pin QFN 2.33 W 23.3 mW/°C 0.93 W 24-pin TSSOP 0.778 W 7.8 mW/°C 0.31 W PACKAGE RECOMMENDED OPERATING CONDITIONS over operating free-air temperature range (unless otherwise noted) VIN VI Supply input voltage Input voltage MIN MAX VIN 4.5 24 V5FILT 4.5 5.5 VBST1, VBST2 –0.1 30 VBST1 - SW1, VBST2 - SW2 –0.1 5.5 VFB1, VFB2, VO1, VO2 –0.1 5.5 TRIP1, TRIP2 –0.1 0.3 EN1, EN2 –0.1 24 SW1, SW2 –1.8 24 UNIT Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 V V 3 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com RECOMMENDED OPERATING CONDITIONS (continued) over operating free-air temperature range (unless otherwise noted) MIN MAX DRVH1, DRVH2 –0.1 30 VBST1 - SW1, VBST2 - SW2 –0.1 5.5 DRVL1, DRVL2, VREG5, SS1, SS2 –0.1 5.5 PGND1, PGND2 UNIT VO Output voltage V –0.1 0.1 TA Operating free-air temperature –40 85 °C TJ Operating junction temperature –40 125 °C TYP MAX UNIT 450 800 μA 30 60 μA 1 % ELECTRICAL CHARACTERISTICS over operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS MIN SUPPLY CURRENT IIN VIN supply current VIN current, TA = 25°C, VREG5 tied to V5FILT, EN1 = EN2 = 5 V, VFB1 = VFB2 = 0.8 V, SW1 = SW2 = 0.5 V IVINSDN VIN shutdown current VIN current, TA = 25°C, no load , EN1 = EN2 = 0 V, VREG5 = ON VFB VOLTAGE AND DISCHARGE RESISTANCE VBG Bandgap initial regulation accuracy TA = 25°C TA = 25°C, SWinj = OFF VVFBTHx VFBx threshold voltage TA = 0°C to 70°C, SWinj = OFF (1) TA = -40°C to 85°C, SWinj = OFF (1) IVFB VFB input current VFBx = 0.8 V, TA = 25°C RDischg VO discharge resistancee ENx = 0 V, VOx = 0.5 V, TA = 25°C –1 755 765 775 753.5 776.5 752 778 –100 mV –10 100 nA 40 80 Ω 5.0 5.2 V VREG5 OUTPUT VVREG5 VREG5 output voltage TA = 25°C, 5.5 V < VIN < 24 V, 0 < IVREG5 < 10 mA VLN5 Line regulation 5.5 V < VIN < 24 V, IVREG5 = 10 mA 20 mV VLD5 Load regulation 1 mA < IVREG5 < 10 mA 40 mV Output current VIN = 5.5 V, VREG5 = 4.0 V, TA = 25°C IVREG5 4.8 170 mA OUTPUT: N-CHANNEL MOSFET GATE DRIVERS RDRVH DRVH resistance RDRVL DRVL resistance TD Dead time Source, IDRVHx = –100 mA 5.5 11 Sink, IDRVHx = 100 mA 2.5 5 Source, IDRVLx = –100 mA 4 8 Sink, IDRVLx = 100 mA 2 4 Ω Ω DRVHx-low to DRVLx-on 20 50 80 DRVLx-low to DRVHx-on 20 40 80 Forward voltage VVREG5-VBSTx, IF = 10 mA, TA = 25°C 0.7 0.8 0.9 V VBST leakage current VBSTx = 29 V, SWx = 24 V, TA = 25°C 0.1 1 μA ns INTERNAL BOOST DIODE VFBST IVBSTLK ON-TIME TIMER CONTROL TON1L CH1 on time SW1 = 12 V, VO1 = 1.8 V 490 ns TON2L CH2 on time SW2 = 12 V, VO2 = 1.8 V 390 ns (1) 4 Not production tested - ensured by design. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 ELECTRICAL CHARACTERISTICS (continued) over operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS TOFF1L CH1 min off time SW1 = 0.7 V, TA = 25°C, VFB1 = 0.7 V TOFF2L CH2 min off time SW2 = 0.7 V, TA = 25°C, VFB2 = 0.7 V MIN TYP MAX UNIT 285 ns 285 ns SOFT START ISSC SS1/SS2 charge current VSS1/VSS2 = 0 V, TA = 25°C TCISSC ISSC temperature coefficient On the basis of 25°C (1) –1.5 –2 ISSD SS1/SS2 discharge current VSS1/VSS2 = 0.5 V 100 150 Wake up 3.7 4.0 4.3 Hysteresis 0.2 0.3 0.4 2.0 –4 μA –2.5 3 nA/°C μA UVLO VUV5VFILT V5FILT UVLO threshold V LOGIC THRESHOLD VENH ENx high-level input voltage EN 1/2 VENL ENx low-level input voltage EN 1/2 V 0.3 V CURRENT SENSE ITRIP TRIP source current VTRIPx = 0.1 V, TA = 25°C TCITRIP ITRIP temperature coefficient On the basis of 25°C VOCLoff VRtrip OCP compensation offset Current limit threshold setting range 8.5 10 ppm/°C (VTRIPx-GND-VPGNDx-SWx) voltage, VTRIPx-GND = 60 mV, TA = 25°C –15 (VTRIPx-GND-VPGNDx-SWx) voltage, VTRIPx-GND = 60 mV –20 20 30 300 VTRIPx-GND voltage 0 μA 11.5 4000 15 mV mV OUTPUT UNDERVOLTAGE AND OVERVOLTAGE PROTECTION VOVP Output OVP trip threshold TOVPDEL Output OVP prop delay VUVP Output UVP trip threshold TUVPDEL Output UVP delay TUVPEN Output UVP enable delay OVP detect 110 115 120 UVP detect 65 Hysteresis (recover < 20 μs) UVP enable delay / soft-start time 70 % μs 1.5 75 10 % 17 30 40 μs x1.4 x1.7 x2.0 ms THERMAL SHUTDOWN TSDN (2) Thermal shutdown threshold Shutdown temperature Hysteresis (2) (2) 150 20 °C Not production tested - ensured by design. TERMINAL FUNCTIONS PIN Fucntion Table TERMINAL NAME QFN 24 TSSOP 24 I/O DESCRIPTION VBST1, VBST2 23, 8 2, 11 I Supply input for high-side NFET driver. Bypass to SWx with a high-quality 0.1-μF ceramic capacitor. An external schottky diode can be added from VREG5 if forward drop is critical to drive the high-side FET. EN1, EN2 24, 7 3, 10 I Enable. Pull High to enable SMPS. VO1, VO2 1, 6 4, 9 I Output voltage inputs for on-time adjustment and output discharge. Connect directly to the output voltage. VFB1, VFB2 2, 5 5, 8 I D-CAP2 feedback inputs. Connect to output voltage with resistor divider. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 5 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com PIN Fucntion Table (continued) TERMINAL QFN 24 TSSOP 24 I/O 3 6 I Signal ground pin. Connect to PGND1, PGND2 and system ground at a single point. DRVH1, DRVH2 22, 9 1, 12 O High-side N-Channel MOSFET gate driver outputs. SWx referenced drivers switch between SWx (OFF) and VBSTx (ON). SW1, SW2 21, 10 24, 13 I/O Switch node connections for both the high-side drivers and the over current comparators. DRVL1, DRVL2 20, 11 23, 14 O Low-side N-Channel MOSFET gate driver outputs. PGND referenced drivers switch between PGNDx (OFF) and VREG5 (ON). PGND1, PGND2 19, 12 22, 15 I/O Power ground connections for both the low-side drivers and the over current comparators. Connect PGND1, PGND2 and GND strongly together near the IC. TRIP1, TRIP2 18, 13 21, 16 I Over current threshold programming pin. Connect to GND with a resistor to GND to set threshold for low-side RDS(ON) current limit. VIN 17 20 I Supply Input for 5-V linear regulator. Bypass to GND with a minimum high-quality 0.1-μF ceramic capacitor. V5FILT 15 18 I 5-V supply input for the entire control circuitry except the MOSFET drivers. Bypass to GND with a minimum high-quality 1.0-μF ceramic capacitor. V5FILT is connected to VREG5 via an internal 10-Ω resistor. VREG5 16 19 O Output of 5-V linear regulator and supply for MOSFET drivers. Bypass to GND with a minimum high-quality 4.7-μF ceramic capacitor. VREG5 is connected to V5FILT via an internal 10-Ω resistor. 4,14 7, 17 O Soft-start programming pin. Connect capacitor from SSx pin to GND to program soft-start time. NAME GND SS1, SS2 DESCRIPTION TSSOP PACKAGE (TOP VIEW) 6 PGND1 DRVH1 VBST1 EN1 VO1 VFB1 GND 19 DRVL1 20 SW1 21 DRVH1 22 VBST1 23 24 EN1 QFN PACKAGE (TOP VIEW) SS1 4 15 V5 FILT VFB2 5 14 SS 2 EN2 VBST2 VO2 6 13 TRIP2 DRVH2 12 VREG5 11 16 DRVL2 3 PGND2 GND 10 VIN SW2 17 9 2 DRVH2 VFB1 8 TRIP1 VBST2 18 7 1 EN2 VO1 SS1 VFB2 VO2 Submit Documentation Feedback 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 SW1 DRVL1 PGND1 TRIP1 VIN VREG5 V5FILT SS2 TRIP2 PGND2 DRVL2 SW2 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 FUNCTIONAL BLOCK DIAGRAM SS2 SW2 SS1 SW1 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 7 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com SWX 8 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 DETAILED DESCRIPTION PWM Operation The main control loop of the TPS53125 is an adaptive on-time pulse width modulation (PWM) controller using a proprietary D-CAP2™ mode control. D-CAP2™ mode control combines constant on-time control with an internal compensation circuit for pseudo-fixed frequency and low external component count configuration with both low ESR and ceramic output capacitors. It is stable even with virtually no ripple at the output. At the beginning of each cycle, the synchronous high-side MOSFET is turned on. After an internal one-shot timer expires, this MOSFET is turned off. When the feedback voltage falls below the reference voltage, the one-shot timer is reset and the high-side MOSFET is turned back on. The one shot is set by the converter input voltage VIN, and the output voltage VO, to maintain a pseudo-fixed frequency over the input voltage range. An internal ramp is added to the reference voltage to simulate output ripple, eliminating the need for ESR induced output ripple from D-CAP mode control. Drivers Each channel of the TPS53125 contains two high-current resistive MOSFET gate drivers. The low-side driver is a PGND referenced, VREG5 powered driver designed to drive the gate of a high-current, low RDS(ON) N-channel MOSFET whose source is connected to PGND. The high-side driver is a floating SWx referenced VBST powered driver designed to drive the gate of a high-current, low RDS(ON) N-channel MOSFET. To maintain the VBST voltage during the high-side driver ON time, a capacitor is placed from SWx to VBSTx. Each driver draws average current equal to gate charge (Qg at Vgs = 5 V) times switching frequency (fSW). To prevent cross-conduction, there is a narrow dead-time when both high-side and low-side drivers are OFF between each driver transition. During this time the inductor current is carried by one of the MOSFETs body diodes. PWM Frequency and Adaptive On-Time Control TPS53125 employs adaptive on-time control scheme and does not have a dedicated on board oscillator. TPS53125 runs with pseudo-constant frequency by using the input voltage and output voltage to set the on-time one-shot timer. The on-time is inversely proportional to the input voltage and proportional to the output voltage. Therefore, when the duty ratio is VOUT/VIN, the frequency is constant. 5-Volt Regulator The TPS53125 has an internal 5-V low-dropout (LDO) regulator to provide a regulated voltage for all both drivers and the IC's internal logic. A high-quality 4.7-μF or greater ceramic capacitor from VREG5 to GND is required to stabilize the internal regular. An internal 10-Ω resistor from VREG5 filters the regulator output to the IC's analog and logic input voltage, V5FILT. An additional high-quality 1.0-μF ceramic capacitor is required from V5FILT to GND to filter switching noise from VREG5. Soft Start The TPS53125 has a programmable soft-start . When the ENx pin becomes high, 2.0-μA current begins charging the capacitor connected from the SS pin to GND. The internal reference for the D-CAP2™ mode control comparator is overridden by the soft-start voltage until the soft-start voltage is greater than the internal reference for smooth control of the output voltage during start up. Pre-Bias Support The TPS53125 supports pre-bias start-up without sinking current from the output capacitor. When enabled, the low-side driver is held off until the soft-start commands a voltage higher than the pre-bias level (internal soft-start becomes greater than feedback voltage (VFB)), then the TPS53125 slowly activates synchronous rectification by limiting the first DRVL pulses with a narrow on-time. This limited on-time is then incremented on a cycle-by-cycle basis until it coincides with the full 1-D off-time. This scheme prevents the initial sinking of current from the pre-bias output, and ensure that the output voltage (VOUT) starts and ramps up smoothly into regulation and the control loop is given time to transition from pre-biased start-up to normal mode operation. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 9 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com Output Discharge Control TPS53125 discharges the outputs when ENx is low, or the controller is turned off by the protection functions (OVP, UVP, UVLO, and thermal shutdown). The device discharges output using an internal 40-Ω MOSFET which is connected to VOx and PGNDx. The external low-side MOSFET is not turned on during the output discharge operation to avoid the possibility of causing negative voltage at the output. This discharge ensures that on start the regulated voltage always initializes from 0 V. Over Current Limit TPS53125 has cycle-by-cycle over current limit feature. The over current limits the inductor valley current by monitoring the voltage drop across the low-side MOSFET RDS(ON) during the low-side driver on-time. If the inductor current is larger than the over current limit (OCL), the TPS53125 delays the start of the next switching cycle until the sensed inductor current falls below the OCL current. MOSFET RDS(ON) current sensing is used to provide an accuracy and cost effective solution without external devices. To program the OCL, the TRIP pin should be connected to GND through a trip voltage setting resistor, according to the following equations. ( ) (VIN - VO) VO VTRIP = IOCL - ¾ · ¾ 2 · L1 · fSW VIN · RDS(ON) (1) VTRIP (mV) RTRIP (kW) = ¾ ITRIP (mA) (2) The trip voltage should be between 30 mV to 300 mV over all operational temperature, including the 4000-ppm/°C temperature slope compensation for the temperature dependency of the RDS(ON). If the load current exceeds the over current limit, the voltage will begin to drop. If the over current conditions continues the output voltage will fall below the under voltage protection threshold and the TPS53125 will shut down. In an over current condition, the current to the load exceeds the current to the output capacitor; thus the output voltage tends to fall off. Eventually, it will end up with crossing the under voltage protection threshold and shutdown. Over/Under Voltage Protection TPS53125 monitors a resistor divided feedback voltage to detect over and under voltage. If the feedback voltage is higher than 115% of the reference voltage, the OVP comparator output goes high and the circuit latches the high-side MOSFET driver OFF and the low-side MOSFET driver ON. When the feedback voltage is lower than 70% of the reference voltage, the UVP comparator output goes high and an internal UVP delay counter begins counting. After 30 μs, TPS53125 latches OFF both top and bottom MOSFET drivers. This function is enabled approximately 1.7 x TSS after power-on. The OVP and UVP latch off is reset when EN goes low level. UVLO Protection TPS53125 has V5FILT under voltage lock out protection (UVLO) that monitors the voltage of V5FILT pin. When the V5FILT voltage is lower than UVLO threshold voltage, the device is shut off. All output drivers are OFF and output discharge is ON. The UVLO is non-latch protection. Thermal Shutdown The TPS53125 includes an over temperature protection shut-down feature. If the TPS53125 die temperature exceeds the OTP threshold (typically 150°C), both the high-side and low-side drivers are shut off, the output voltage discharge function is enabled and then the device is shut off until the die temperature drops. Thermal shutdown is a non-latch protection. 10 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 TYPICAL CHARACTERISTICS VIN SUPPLY CURRENT vs JUNCTION TEMPERATURE VIN SHUTDOWN CURRENT vs JUNCTION TEMPERATURE 60 -m 50 40 30 20 10 VREG5=ON 0 -50 0 50 100 Figure 3. Figure 4. TRIP SOURCE CURRENT vs JUNCTION TEMPERATURE VREG5 VOLTAGE vs JUNCTION TEMPERATURE 150 5.070 IT R IP - S o u r c e C u r r e n t - m A 5.060 VREG5 Voltage - V 5.050 5.040 5.030 5.020 5.010 TJ - Junction Temperature - °C 5.000 -50 Figure 5. 0 50 100 Temperature - °C 150 Figure . Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 11 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com TYPICAL CHARACTERISTICS (continued) VREG5 VOLTAGE vs INPUT VOLTAGE 5.500 VREG5 Voltage - V 5.300 5.100 4.900 4.700 4.500 0 5 10 15 20 25 VIN - Input Voltage - V Figure 6. 12 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 TYPICAL APPLICATION PERFORMANCE SWITCHING FREQUENCY (IO1 = 3 A) vs INPUT VOLTAGE (CH1) SWITCHING FREQUENCY (IO2 = 3 A) vs INPUT VOLTAGE (CH2) 500 fSW - Switching Frequency - kHz fSW - Switching Frequency - kHz 500 400 300 200 100 400 300 200 100 Vo1 = 1.8 V VO2 = 1.05 V 0 0 0 5 10 15 20 25 0 5 10 VIN - Input Voltage - V Figure 8. SWITCHING FREQUENCY (VIN = 12 V) vs OUTPUT CURRENT (CH1) SWITCHING FREQUENCY (VIN = 12 V) vs OUTPUT CURRENT (CH2) 25 500 fSW - Switching Frequency - kHz fSW - Switching Frequency - kHz 20 Figure 7. 500 400 300 200 100 0 0.0 15 VIN - Input Voltage - V VO1 = 1.8 V 400 300 200 100 VO2 = 1.05 V 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 IO - Output Current - A 1.0 1.5 2.0 2.5 3.0 3.5 4.0 IO - Output Current - A Figure 9. Figure 10. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 13 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com OUTPUT VOLTAGE (VIN = 12 V) vs OUTPUT CURRENT (CH2) 1.850 1.100 1.840 1.090 1.830 1.080 VOUT - Output Voltage - V VOUT - Output Voltage - V OUTPUT VOLTAGE (VIN = 12 V) vs OUTPUT CURRENT (CH1) 1.820 1.810 1.800 1.790 1.780 1.770 VO1 = 1.8 V 1.760 1.060 1.050 1.040 1.030 1.020 VO2 = 1.05 V 1.010 1.750 0.0 1.070 1.000 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 2.0 2.5 3.0 Figure 11. Figure 12. OUTPUT VOLTAGE (VIN = 12 V) vs INPUT VOLTAGE (CH1) OUTPUT VOLTAGE (VIN = 12 V) vs INPUT VOLTAGE (CH2) 1.850 1.100 1.840 1.090 1.830 1.080 1.820 1.810 1.800 1.790 1.780 3.5 4.0 1.070 1.060 1.050 1.040 1.030 1.020 1.770 VO2 = 1.05 V VO1 = 1.85 V 1.010 1.760 1.000 1.750 0 5 10 15 20 25 0 VIN - Input Voltage - V 5 10 15 20 25 VIN - Input Voltage - V Figure 13. 14 1.5 IOUT - Output Current - A VOUT - Output Voltage - V VOUT - Output Voltage - V IOUT - Output Current - A Figure 14. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 LOAD TRANSIENT RESPONSE LOAD TRANSIENT RESPONSE VO2 = 1.05 V (50 mV/div) VO1 = 1.8 V (50 mV/div) IOUT1 (2 A/div) IOUT2 (2 A/div) Figure 15. Figure 16. START-UP WAVEFORMS START-UP WAVEFORMS EN2 (5 V/div) EN1 (5 V/div) SS2 (0.2 V/div) SS1 (0.2 V/div) VO1 = 1.8 V (0.5 V/div) VO2 = 1.05 V (0.5 V/div) Figure 17. Figure 18. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 15 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com 1.05-V EFFICIENCY vs OUTPUT CURRENT (CH2) 100 100 80 80 Efficiency - % Efficiency - % 1.8-V EFFICIENCY vs OUTPUT CURRENT (CH1) 60 40 40 20 20 VO1 = 1.8 V VO2 = 1.05 V 0 0 0.0 60 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 3.0 Figure 19. Figure 20. 1.8-V OUTPUT RIPPLE VOLTAGE 1.05-V OUTPUT RIPPLE VOLTAGE VO1 (20 mV/div) 3.5 4.0 VO2 (20 mV/div) VO1 = 1.8 V Figure 21. 16 2.5 IOUT - Output Current - A IOUT - Output Current - A VO2 = 1.05 V Figure 22. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 APPLICATION INFORMATION 1. Choose inductor. The inductance value is selected to provide approximately 30% peak to peak ripple current at maximum load. Larger ripple current increases output ripple voltage, improve S/N ratio and contribute to stable operation. Equation 3 can be used to calculate L1. L1 = (VIN(MAX) - VO1) VO1 (VIN(MAX) - VO1) ¾ · ¾ = ¾ IL1(RIPPLE) · fSW VIN(MAX) 0.3 · IO1 · fSW · Vo1 ¾ VIN(MAX) (3) The inductors current ratings needs to support both the RMS (thermal) current and the Peak (saturation) current. The RMS and peak inductor current can be estimated as follows. VIN(MAX) - VO1 IL1(RIPPLE) = ¾ L1 · fSW · Vo1 ¾ VIN(MAX) (4) VTRIP ¾ IL1(PEAK) = R + IL1(RIPPLE) DS(ON) ¾ 2 1 (I IL1(RMS) = IO 12 + ¾ ) 12 L1(RIPPLE) (5) Ö (6) Note: The calculation above shall serve as a general reference. To further improve transient response, the output inductance could be reduced further. This needs to be considered along with the selection of the output capacitor. 2. Choose output capacitor. The capacitor value and ESR determines the amount of output voltage ripple and load transient response. it is recommended to use a ceramic output capacitor. IL1(RIPPLE) C1 = ¾ 8 · VO1(RIPPLE) · 1 ¾ fSW (7) 2 D Iload · L1 C1 = ¾ 2 · VO1 · DVOS (8) 2 load · L1 DI C1 = ¾ 2 · K · DVOS (9) Where Ton1 K = (VIN - VO 1) · ¾ Ton1 + Tmin(off) (10) Select the capacitance value greater than the largest value calculated from Equation 7, Equation 8 and Equation 9. The capacitance for C1 should be greater than 66 μF. Where ΔVOS = The allowable amount of overshoot voltage in load transition ΔVUS = The allowable amount of undershoot voltage in load transition Tmin(off) = Minimum off time 3. Choose input capacitor. The TPS53125 requires an input decoupling capacitor and a bulk capacitor is needed depending on the application. A minimum 10-μF high-quality ceramic capacitor is recommended for the input capacitor. The capacitor voltage rating needs to be greater than the maximum input voltage. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 17 TPS53125 SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 www.ti.com 4. Choose bootstrap capacitor. The TPS53125 requires a bootstrap capacitor from SW to VBST to provide the floating supply for the high-side drivers. A minimum 0.1-μF high-quality ceramic capacitor is recommended. The voltage rating should be greater than 10 V. 5. Choose VREG5 and V5FILT capacitor. The TPS53125 requires both the VREG5 regulator and V5FILT input are bypassed. A minimum 4.7-μF high-quality ceramic capacitor must be connected between the VREG5 and GND for proper operation. A minimum 1-μF high-quality ceramic capacitor must be connected between the V5FILT and GND for proper operation. Both of these capacitors’ voltage ratings should be greater than 10 V. 6. Choose output voltage divider resistors. The output voltage is set with a resistor divider from the output voltage node to the VFBx pin. It is recommended to use 1% tolerance or better resisters. Select R2 between 10 kΩ and 100 kΩ and use Equation 11 or Equation 12 to calculate R1. Vswinj = (VIN - VO1 · 0.5875) · R1 = ( )( ) 1 ¾ fSW ( VO1 ¾ VIN · ) VO 1 -1 ¾ VFB(RIPPLE) + Vswinj VFB + ¾ 2 · · 5472 (11) R2 (12) Where VFB(RIPPLE) = Ripple voltage at VFB Vswinj = Ripple voltage at error comparator 7. Choose register setting for over current limit. VTRIP = ( ) (VIN - VO) VO ·¾ IOCL - ¾ 2 · L1 · fSW VIN · RDS(ON) (13) VTRIP (mV) - VOCLoff RTRIP (kW) = ¾ ITRIP(min) (mA) (14) Where RDS(ON) = Low side FET on-resistance ITRIP(min) = TRIP pin source current 8.5 μA VOCL0ff = Minimum over current limit offset voltage (–20 mV) IOCL = Over current limit 8. Choose soft start capacitor. Soft start time equation is as follows. TSS · ISSC CSS = ¾ VFB 18 (15) Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 TPS53125 www.ti.com SLVS947A – OCTOBER 2009 – REVISED OCTOBER 2009 LAYOUT SUGGESTIONS • • • • • • Keep the input switching current loop as small as possible. Place the input capacitor (C3,C6) close to the top switching FET. The output current loop should also be kept as small as possible. Keep the SW node as physically small and short as possible as to minimize parasitic capacitance and inductance and to minimize radiated emissions. Kelvin connections should be brought from the output to the feedback pin (FBx) of the device. Keep analog and non-switching components away from switching components. Make a single point connection from the signal ground to power ground. Do not allow switching current to flow under the device. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS53125 19 PACKAGE OPTION ADDENDUM www.ti.com 5-Nov-2009 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty TPS53125PW ACTIVE TSSOP PW 24 TPS53125PWR ACTIVE TSSOP PW 24 60 Lead/Ball Finish MSL Peak Temp (3) Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 MECHANICAL DATA MTSS001C – JANUARY 1995 – REVISED FEBRUARY 1999 PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PINS SHOWN 0,30 0,19 0,65 14 0,10 M 8 0,15 NOM 4,50 4,30 6,60 6,20 Gage Plane 0,25 1 7 0°– 8° A 0,75 0,50 Seating Plane 0,15 0,05 1,20 MAX PINS ** 0,10 8 14 16 20 24 28 A MAX 3,10 5,10 5,10 6,60 7,90 9,80 A MIN 2,90 4,90 4,90 6,40 7,70 9,60 DIM 4040064/F 01/97 NOTES: A. B. C. D. All linear dimensions are in millimeters. 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