TMI3253

TMI3253/S/T 600kHz 18V 3.5A Synchronous COT Step-Down Converter Features Description ⚫ 70mΩ/35mΩ Low RDS(ON) internal FETs The TMI3253 is a high efficiency 600kHz, Constant ⚫ High Efficiency Synchronous-Mode on-Time (COT) control mode synchronous step- Operation down DC-DC converter capable of delivering up to 3.5A current with 1.2V output voltage. TMI3253 ⚫ Wide Input Range:4.5V to 18V ⚫ Output Voltage from 0.8V(TMI3253) ⚫ 600kHz Switch Frequency ⚫ Up to 3.5A/1.2V Output Current and capacitor size are achieved with 600kHz ⚫ COT control to achieve fast transient switching frequency. It adopts the COT architecture responses to achieve fast transient responses for high voltage ⚫ Power Save Mode at Light Load step down applications. ⚫ Integrated internal compensation The TMI3253 requires a minimum number of readily ⚫ Stable with Low ESR Ceramic Output available standard external components and is Capacitors available in a 6-pin SOT23-6 ROHS compliant integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. Low output voltage ripple and small external inductor ⚫ Over Current Protection with Hiccup Mode ⚫ Thermal Shutdown ⚫ Inrush Current Limit and Soft Start ⚫ Build in Input Over Voltage Protection ⚫ Available in SOT23-6 Package package. Application ⚫ Digital Set Top Boxes ⚫ Flat Panel Television and Monitors ⚫ Notebook computer ⚫ Wireless and DSL Modems Typical Application Efficiency C4 0.1µF VOUT=3.3V, IOUT=0.01A to 3.5A, TA=25°C BS VIN CIN1 CIN2 22µF 100nF 2 L 4.7µH VOUT= 3.3V LX R3 100kΩ R1 39kΩ 5 Cfb 20pF~ 100pF 4 EN FB GND CO1 R2 12.5kΩ 1 22µF CO2 22µF 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% 0.01 Efficiency 6 3 Vin=9V Vin=12V Vin=16V 0.1 1 10 Output Current (A) TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev. 0.1 – 2018.10 www.toll-semi.com www.suntosemi.com 1 TMI3253/S/T Absolute Maximum Ratings(Note 1) Parameter Min Max Unit Input Supply Voltage, EN LX Voltages FB Voltage BS Voltage Storage Temperature Range Junction Temperature (Note2) Power Dissipation Lead Temperature (Soldering, 10s) -0.3 -0.3 -0.3 -0.3 -65 20 20 6 23 150 V V V V °C °C mW °C 160 1000 260 Package GND 1 6 BS BS 1 6 LX LX 2 5 EN GND 2 5 IN IN 3 4 FB FB 3 4 EN SOT23-6 SOT23-6 Top Marking: TM3XXX / TT3XXX Top Marking: TS3XXX TM3/TT3: Device Code TS3: Device Code XXX: Inside Code XXX: Inside Code Order Information Part Number Package Top Marking Quantity/Reel TMI3253 SOT23-6 TM3XXX 3000 TMI3253S SOT23-6 TS3XXX 3000 TMI3253T SOT23-6 TT3XXX 3000 www.toll-semi.com www.suntosemi.com 2 TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev.0.1 – 2018.10 TMI3253/S/T Pin Functions Pin Name Function TMI3253/T TMI3253S 1 2 GND 2 6 LX Switching Pin 3 5 IN Power supply Pin 4 3 FB 5 4 EN 6 1 BS Ground Pin Output Voltage feedback input. Connect FB to the center point of the external resistor divider. Drive this pin to a logic-high to enable the IC. Drive to a logic-low to disable the IC and enter micro-power shutdown mode. Don’t floating. Bootstrap. A capacitor connected between LX and BST pins is required to form a floating supply across the high-side switch driver. ESD Rating Items Description Value Unit ESD Human Body Model for all pins ±2000 V JEDEC specification JS-001 Recommended Operating Conditions Items Description Min Max Unit Voltage Range IN 4.5 18 V TJ Operating Junction Temperature -40 125 °C Thermal Resistance(Note3) Items Description Value Unit θJA Junction-to-ambient thermal resistance 100 °C/W TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev. 0.1 – 2018.10 www.toll-semi.com www.suntosemi.com 3 TMI3253/S/T Electrical Characteristics(Note 4) VIN=12V, VOUT=3.3V, TA = 25°C, unless otherwise noted. Parameter Conditions Input Voltage Range Min Typ 4.5 OVP Threshold Max Unit 18 V 19.3 UVLO Rising Threshold V 4.0 UVLO Hysteresis Quiescent Current VEN=2V, VFB=VREF x 105% Shutdown Current VIN=12V, EN=0V V 0.45 V 300 μA 5 10 μA Regulated Feedback Voltage(3253) TA=25°C,4.5V≤VIN≤18V 0.784 0.8 0.816 V Regulated Feedback Voltage(3253S) TA=25°C,4.5V≤VIN≤18V 0.588 0.6 0.612 V Regulated Feedback Voltage(3253T) TA=25°C,4.5V≤VIN≤18V 0.750 0.765 0.780 V High-Side Switch On-Resistance 70 mΩ Low-Side Switch On-Resistance 35 mΩ High-Side Switch Leakage Current VEN=0V, VLX=0V Switch Valley Current Limit Minimum Duty Cycle On Time VIN=12V, VOUT=1.2V, IOUT=1A 1 10 4 132 Oscillation Frequency 166 μA A 200 ns 600 kHz 65 % Minimum On-Time 80 ns Soft Start Time 1 ms Hiccup on Time 1.4 ms 4 ms Maximum Duty Cycle VFB=0.8V Hiccup Time Before Restart EN High-Level Input Voltage 1.5 V EN Low-Level Input Voltage 0.3 V Thermal Shutdown 165 °C Thermal Shutdown Threshold 30 °C Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + PD x θJA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ(MAX)-TA)/θJA. Note 3: Measured on JESD51-7, 4-layer PCB. Note 4: 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. www.toll-semi.com www.suntosemi.com 4 TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev.0.1 – 2018.10 TMI3253/S/T Block Diagram EN VIN BS Regulator UVLO OVP Vuv + OTP Hiccup - FB + EA + Voltage Reference LX Logic Control PWM Comparator Gate Driver VCOMP + - ON time Generater + ZC - Soft Start Current Sense and OCP GND Figure 1. TMI3253 Block Diagram Operation Description Internal Regulator The TMI3253 is a constant on-time (COT) step down DC/DC converter that provides excellent transient response with no extra external compensation components. This device contains low resistance, high voltage high side and low side power MOSFETs, and operates at 600kHz operating frequency to ensure a compact, high efficiency design with excellent AC and DC performance. Error Amplifier TMI3253 adopts operational transconductance amplifier (OTA) as error amplifier. The error amplifier compares the FB pin voltage with the internal FB reference (VREF) and outputs a current proportional to the difference between the two. This output current is then used to charge or discharge the internal compensation network to form the VCOMP voltage, which is used to compare with the low side power MOSFET current sensing signal and trigger on time pulse. The optimized internal compensation network minimizes the external component counts and simplifies the control loop design. TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev. 0.1 – 2018.10 www.toll-semi.com www.suntosemi.com 5 TMI3253/S/T Internal Soft-Start The soft-start is implemented to prevent the converter output voltage from overshooting during startup. When the chip starts, the internal circuitry generates a soft-start voltage (SS) ramping up from 0V to 0.8V. When it is lower than the internal FB reference (VREF), SS overrides REF so the error amplifier uses SS as the reference. When SS is higher than VREF, VREF regains control. The SS time is internally fixed to 1ms typically. Over-Current-Protection and Short Circuits Protection The TMI3253 has cycle-by-cycle valley current limit function. When the inductor current valley value is larger than the valley current limit during low side MOSFET on state, the device enters into valley over current protection mode and low side MOSFET keeps on state until inductor current drops down to the value equal or lower than the valley current limit, and then on time pulse could be generated and high side MOSFET could turn on again. If the output is short to GND and the output voltage drop until feedback voltage VFB is below the output under-voltage VUV threshold which is typically 35% of VREF, TMI3253 enters into hiccup mode to periodically disable and restart switching operation. The hiccup mode helps to reduce power dissipation and thermal rise during output short condition. The period of TMI3253 hiccup mode is typically 5.4ms. Startup and Shutdown If both VIN and EN are higher than their appropriate thresholds, the chip starts switching operation. The reference block starts first, generating stable reference voltage and currents, and then the internal regulator is enabled. The regulator provides stable supply for the remaining circuitries. Three events can shut down the chip: EN low, VIN low and thermal shutdown. In the shutdown procedure, the signaling path is first blocked to avoid any fault triggering. The VCOMP voltage and the internal supply rail are then pulled down. The floating driver is not subject to this shutdown command. Application Information Setting the Output Voltage The external resistor divider is used to set the output voltage (see Typical Application on page 1). Choose R1 to be around 39kΩ for optimal transient response. R2 is then given by: Table 1: Selection for Common Output Voltages(VFB=0.8V) VOUT (V) R1 (kΩ) R2 (kΩ) CFB(pF) L (μH) 5 39 7.43 33 4.7 3.3 39 12.5 33 4.7 2.5 39 18.3 33 3.3 1.8 39 31.2 33 2.2 1.5 39 44.6 33 2.2 1.2 39 78 33 1.5 1 18 72 33 1.0 www.toll-semi.com www.suntosemi.com 6 R2 = R1 Vout /VFB − 1 C fb=20pF~100pF TMI3253 VOUT FB R1 R2 Figure 2. Feedback Network TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev.0.1 – 2018.10 TMI3253/S/T Selecting the Inductor A 1.0μH to 4.7μH inductor with a DC current rating of at least 25% percent higher than the maximum load current is recommended for most applications. For highest efficiency, the inductor DC resistance should be as small as possible. For most designs, the inductance value can be derived from the following equation. V  (Vin − Vout ) L = out Vin  I L  fOSC Where ΔIL is the inductor ripple current. Choose inductor ripple current to be approximately 30% if the maximum load current, 3A. The maximum inductor peak current is: I L 2 Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. I L ( MAX ) = I LOAD + Selecting the Output Capacitor The output capacitor (Co1 and Co2) is required to maintain the DC output voltage. Ceramic, tantalum, or low ESR electrolytic capacitors are recommended. Low ESR capacitors are preferred to keep the output voltage ripple low. The output voltage ripple can be estimated by: VOUT =  VOUT  VOUT   1  1 −   RESR +  f S  L  VIN   8  f S  C2  Where L is the inductor value and RESR is the equivalent series resistance (ESR) value of the output capacitor. In the case of ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance. The output voltage ripple is mainly caused by the capacitance. For simplification, the output voltage ripple can be estimated by: VOUT =  V   1 − OUT  8  f S  L  C 2  VIN  VOUT 2 In the case of tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For simplification, the output ripple can be approximated to: VOUT = VOUT  VOUT   1 −   RESR f S  L  VIN  The characteristics of the output capacitor also affect the stability of the regulation system. The TMI3253 can be optimized for a wide range of capacitance and ESR values. TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev. 0.1 – 2018.10 www.toll-semi.com www.suntosemi.com 7 TMI3253/S/T Typical Performance Characteristics Efficiency Efficiency VOUT =3.3V, L=4.7μH, DCR=30mΩ VOUT =5V, L=4.7μH, DCR=30mΩ 100% 100% 95% 95% 90% 85% 85% Efficiency Efficiency 90% 80% 75% 80% 75% 70% 65% Vin=9V Vin=12V Vin=16V 70% 65% 60% 0.01 0.1 1 Output Current (A) Vin=9V 60% Vin=12V 55% Vin=16V 50% 0.01 10 0.1 Efficiency 10 Load Regulation VOUT=1.2V, L=2.2μH, DCR=20mΩ VIN=12V, TA=25°C 100% 2.0% 95% Vo=5V 1.5% Output Voltage Regulation 90% 85% Efficienct 1 Output Current (A) 80% 75% 70% Vo=3.3V 1.0% Vo=1.2V 0.5% 0.0% -0.5% 65% Vin=9V 60% -1.0% Vin=12V 55% -1.5% Vin=16V 50% 0.01 0.1 1 10 -2.0% 0 0.5 Output Current (A) Steady State Operation 1 1.5 2 2.5 Output Current (A) 3 3.5 Steady State Operation VIN =12V, VOUT =3.3V, No Load VIN =12V, VOUT =3.3V, Io=Full Load Vout=20mV/div AC coupled Vout=20mV/div AC coupled LX=10V/div LX=10V/div Vin=50mV/div AC coupled Vin=50mV/div AC coupled IL=500mA/div IL=2A/div Time: 2μs/div www.toll-semi.com www.suntosemi.com 8 Time: 1μs/div TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev.0.1 – 2018.10 TMI3253/S/T Typical Performance Characteristics(continued) Load Transient Load Transient VIN =12V, VOUT =3.3V, Io =0A to 3.2A VIN =12V, VOUT =3.3V, Io =1.6A to 3.2A Vout=200mV/div AC coupled Vout=200mV/div AC coupled Io=2A/div Io=2A/div Time: 200μs/div Time: 200μs/div Output Short Entry Output Short Recovery VIN =12V, VOUT =3.3V, No Load VIN=12V, VOUT =3.3V, No Load Vout=2V/div Vout=2V/div Vin=5V/div Vin=5V/div LX=10V/div LX=10V/div IL=5A/div Time: 4ms/div IL=5A/div Input Power On Time: 4ms/div Input Power Down VIN =12V, VOUT =3.3V, Io =Full Load VIN =12V, VOUT =3.3V, Io =Full Load Vout=2V/div Vin=5V/div Vout=2V/div LX=10V/div Vin=5V/div LX=10V/div IL=2A/div TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev. 0.1 – 2018.10 IL=2A/div Time: 10ms/div Time: 400μs/div www.toll-semi.com www.suntosemi.com 9 TMI3253/S/T Typical Performance Characteristics(continued) EN Enable EN Disable VIN =12V, VOUT =3.3V, Io =Full Load VIN =12V, VOUT =3.3V, Io =Full Load Vout=2V/div Vout=2V/div LX=10V/div LX=10V/div EN=5V/div EN=5V/div IL=2A/div IL=2A/div Time: 40μs/div Time: 400μs/div Typical Application Circuits C4 0.1µF 6 3 CIN1 CIN2 22µF 100nF BS VIN 2 L 4.7µH VOUT=5V LX R3 100kΩ R1 39kΩ 5 Cfb 20pF~ 100pF 4 EN FB CO1 R2 7.43kΩ GND 1 22µF CO2 22µF Figure 4. 12VIN, 5V Output (VFB=0.8V) C4 0.1µF 6 3 CIN1 CIN2 22µF 100nF BS VIN 2 L 4.7µH VOUT= 3.3V LX R3 100kΩ R1 39kΩ 5 20pF~ 100pF 4 EN Cfb FB GND 1 CO1 R2 12.5kΩ 22µF CO2 22µF Figure 5. 12VIN, 3.3V Output (VFB=0.8V) www.toll-semi.com www.suntosemi.com 10 TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev.0.1 – 2018.10 TMI3253/S/T Typical Application Circuits(continued) C4 0.1µF 6 3 CIN1 CIN2 22µF 100nF BS VIN 2 L 2.2µH VOUT= 1.8V LX R3 100kΩ R1 39kΩ 5 4 EN Cfb 20pF~ 100pF FB CO1 R2 31.2kΩ GND 1 22µF CO2 22µF Figure 6. 12VIN, 1.8V Output (VFB=0.8V) C4 0.1µF 6 3 CIN1 CIN2 22µF 100nF BS VIN 2 L 2.2µH VOUT= 1.5V LX R3 100kΩ R1 39kΩ 5 20pF~ 100pF 4 EN Cfb FB CO1 R2 44.6kΩ GND 1 22µF CO2 22µF Figure 7. 12VIN, 1.5V Output (VFB=0.8V) C4 0.1µF 6 3 CIN1 CIN2 22µF 100nF BS VIN 2 L 1.5µH VOUT= 1.2V LX R3 100kΩ R1 39kΩ 5 20pF~ 100pF 4 EN Cfb FB CO1 R2 78kΩ GND 1 22µF CO2 22µF Figure 8. 12VIN, 1.2V Output (VFB=0.8V) C4 0.1µF 6 3 CIN1 CIN2 22µF 100nF BS VIN 2 L 1µH VOUT= 1V LX R3 100kΩ R1 18kΩ 5 20pF~ 100pF 4 EN Cfb FB GND 1 CO1 R2 72kΩ 22µF CO2 22µF Figure 9. 12VIN, 1V Output (VFB=0.8V) TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev. 0.1 – 2018.10 www.toll-semi.com www.suntosemi.com 11 TMI3253/S/T PCB Layout Guide PCB layout is very important to achieve stable operation. It is highly recommended to duplicate EVB layout for optimum performance. If change is necessary, please follow these guidelines and take Figure 3 for reference. 1) Keep the path of switching current short and minimize the loop area formed by Input capacitor, IN pin and GND. 2) Bypass ceramic capacitors are suggested to be put close to the IN Pin. 3) Ensure all feedback connections are short and direct. Place the feedback resistors as close to the chip as possible. 4) VOUT, LX away from sensitive analog areas such as FB. 5) Connect IN, LX, and especially GND respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. Top Layer Bottom Layer VOUT VIN LX Figure 3. Sample of PCB Layout(TMI3253) www.toll-semi.com www.suntosemi.com 12 TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev.0.1 – 2018.10 TMI3253/S/T Package Information SOT23-6 Unit: mm Symbol Dimensions In Millimeters Min Max L 2.82 3.02 B 1.50 C Symbol Dimensions In Millimeters Min Max E1 0.85 1.05 1.70 a 0.35 0.50 0.90 1.30 c 0.10 0.20 L1 2.60 3.00 b 0.35 0.55 E 1.80 2.00 F 0 0.15 Note: 1) All dimensions are in millimeters. 2) Package length does not include mold flash, protrusion or gate burr. 3) Package width does not include interlead flash or protrusion. 4) Lead popularity (bottom of leads after forming) shall be 0.10 millimeters max. 5) Pin 1 is lower left pin when reading top mark from left to right. TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev. 0.1 – 2018.10 www.toll-semi.com www.suntosemi.com 13 TMI3253/S/T Tape and Reel Information Tape Dimensions: Reel Dimensions: Note: 1) All Dimensions are in Millimeter 2) Quantity of Units per Reel is 3000 www.toll-semi.com www.suntosemi.com 14 TMI and SUNTO are the brands of TOLL microelectronic TMI3253/S/T Rev.0.1 – 2018.10