SLUSAH4D MARCH   2011  – February 2016 TPS56121

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Voltage Reference
      2. 7.3.2  Enable Functionality, Startup Sequence and Timing
        1. 7.3.2.1 COMP Pin Impedance Sensing
        2. 7.3.2.2 Overcurrent Protection (OCP) Setting
      3. 7.3.3  Soft-Start Time
      4. 7.3.4  Oscillator
      5. 7.3.5  Overcurrent Protection (OCP)
      6. 7.3.6  Switching Node (SW)
      7. 7.3.7  Input Undervoltage Lockout (UVLO)
      8. 7.3.8  Pre-Bias Startup
      9. 7.3.9  Power Good
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Switching Frequency Selection
        2. 8.2.2.2  Inductor Selection (L1)
        3. 8.2.2.3  Output Capacitor Selection
        4. 8.2.2.4  Inductor Peak Current Rating
        5. 8.2.2.5  Input Capacitor Selection
        6. 8.2.2.6  Bootstrap Capacitor (C14)
        7. 8.2.2.7  Bootstrap Resistor (R2)
        8. 8.2.2.8  RC Snubber (R9 and C18)
        9. 8.2.2.9  VDD Bypass Capacitor (C11)
        10. 8.2.2.10 BP5 Bypass Capacitor (C12)
        11. 8.2.2.11 Soft-Start Capacitor (C13)
        12. 8.2.2.12 Current Limit (R1)
        13. 8.2.2.13 Feedback Divider (R4, R7)
        14. 8.2.2.14 Compensation (C15, C16, C17, R3, R6)
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted) (1)
MIN MAX UNIT
Voltage VDD, VIN –0.3 16.5 V
SW –3 25
SW (< 100 ns pulse width, 10 µJ) -5
BOOT –0.3 30
BOOT-SW (differential from BOOT to SW) –0.3 7
COMP, PGOOD, FB, BP, EN/SS, ILIM –0.3 7
Temperature Junction, TJ –40 150 °C
Storage, Tstg –55 150
(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 condition beyond those included under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods of time may affect device reliability.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±1500
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
VDD VIN Input voltage 4.5 14 V
TJ Operating junction temperature –40 125 °C

6.4 Thermal Information

THERMAL METRIC(1) TPS56121 UNIT
DQP
22 PINS
RθJA Junction-to-ambient thermal resistance 34.6 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 22.9
ψJT Junction-to-top characterization parameter 0.6
ψJB Junction-to-board characterization parameter 5.0
RθJC(bot) Junction-to-case (bottom) thermal resistance 0.3
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics

–40°C ≤ TJ ≤ 125°C, VVDD = 12 V, all parameters at zero power dissipation (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOLTAGE REFERENCE
VFB FB input voltage TJ = 25°C, 4.5 V ≤ VVDD ≤ 14 V 597 600 603 mV
–40°C ≤ TJ ≤ 125°C,
4.5 V ≤ VVDD ≤ 14 V		 594 600 606
INPUT SUPPLY
VVDD Input supply voltage range 4.5 14 V
IVDDSD Shutdown supply current VEN/SS = 0.2 V 80 120 µA
IVDDQ Quiescent, non-switching Let EN/SS float, VFB = 1 V 2.5 5.0 mA
VUVLO UVLO ON Voltage 4.0 4.3 V
VUVLO(HYS) UVLO hysteresis 500 700 mV
ENABLE/SOFT-START
VIH High-level input voltage, EN/SS 0.55 0.70 1.00 V
VIL Low-level input voltage, EN/SS 0.27 0.30 0.33 V
ISS Soft-start source current 8 10 12 µA
VSS Soft-start voltage level – Start of ramp 0.4 0.8 1.3 V
BP REGULATOR
VBP Output voltage IBP = 10 mA 6.2 6.5 6.8 V
VDO Regulator dropout voltage, VVDD – VBP IBP = 25 mA, VVDD = 4.5 V 70 125 mV
OSCILLATOR
fSW Switching Frequency RCOMP = 40.2 kΩ, 4.5 V ≤ VVDD ≤ 14 V 270 300 330 kHz
RCOMP = open, 4.5 V ≤ VVDD ≤ 14 V 450 500 550 kHz
RCOMP = 13.3 kΩ, 4.5 V ≤ VVDD ≤ 14 V 0.8 0.95 1.1 MHz
VRAMP(1) Ramp amplitude VVDD/6.6 VVDD/6 VVDD/5.4 V
PWM
DMAX (1) Maximum duty cycle fsw = 300 kHz, VFB = 0 V,
4.5 V ≤ VVDD ≤ 14 V		 93%
fsw = 500 kHz, VFB = 0 V,
4.5 V ≤ VVDD ≤ 14 V		 90%
fsw = 1 MHz, VFB = 0 V,
4.5 V ≤ VVDD ≤ 14 V		 85%
tON(min) (1) Minimum controllable pulse width 100 ns
ERROR AMPLIFIER
GBWP (1) Gain bandwidth product 10 24 MHz
AOL (1) Open loop gain 60 dB
IIB Input bias current (current out of FB pin) VFB = 0.6 V 75 nA
IEAOP Output source current VFB = 0 V 1.5 mA
IEAOM Output sink current VFB = 1 V 1.5 mA
POWER GOOD
VOV Feedback upper voltage limit for PGOOD 655 675 700 mV
VUV Feedback lower voltage limit for PGOOD 500 525 550
VPGD-HYST PGOOD hysteresis voltage at FB 30 45
RPGD PGOOD pull down resistance VFB = 0 V, IFB = 5 mA 30 70 Ω
IPGDLK PGOOD leakage current 550 mV < VFB < 655 mV,
VPGOOD = 5 V		 10 20 µA
OUTPUT STAGE
RHI High-side device resistance TJ = 25°C, (VBOOT – VSW) = 5.5 V 4.5 6.5 mΩ
RLO Low side device resistance TJ = 25°C 1.9 2.7
OVERCURRENT PROTECTION (OCP)
tPSSC(min) (1) Minimum pulse time during short circuit 250 ns
tBLNKH (1) Switch leading-edge blanking pulse time (high-side detection) 150
IOCH OC threshold for high-side FET TJ = 25°C, (VBOOT – VSW) = 5.5 V 27 34 39 A
IILIM ILIM current source TJ = 25°C 10.0 µA
VOCLPRO(1) Programmable OC range for low side FET TJ = 25°C 12 100 mV
tOFF OC retry cycles on EN/SS pin 4 Cycle
BOOT DIODE
VDFWD Bootstrap diode forward voltage IBOOT = 5 mA 0.8 V
THERMAL SHUTDOWN
TJSD (1) Junction shutdown temperature 145 ºC
TJSDH (1) Hysteresis 20 ºC
(1) Ensured by design. Not production tested

6.6 Typical Characteristics

TPS56121 vref01_lusah5.png Figure 1. Reference Voltage vs. Junction Temperature
TPS56121 fsw500kHz_lusah5.png Figure 3. Switching Frequency vs. Junction Temperature (500 kHz)
TPS56121 envih_lusah5.png Figure 5. EN Pin High-Level Threshold Voltage vs. Junction Temperature
TPS56121 ivddsd07_lusah5.png Figure 7. Shutdown Current vs. Junction Temperature
TPS56121 iss09_lusah5.png Figure 9. Soft-Start Source vs. Junction Temperature
TPS56121 rhi11_lusah5.png Figure 11. High-Side On Resistance vs. Junction Temperature
TPS56121 fsw300kHz_lusah5.png Figure 2. Switching Frequency vs. Junction Temperature (300 kHz)
TPS56121 fsw1MHz_lusah5.png Figure 4. Switching Frequency vs. Junction Temperature (1 MHz)
TPS56121 envil_lusah5.png Figure 6. EN Pin Low-Level Threshold Voltage vs. Junction Temperature
TPS56121 ivddq08_lusah5.png Figure 8. Quiescent Current vs. Junction Temperature
TPS56121 vss10_lusah5.png Figure 10. Soft-Start Voltage Level vs. Junction Temperature
TPS56121 rli12_lusah5.png Figure 12. Low-Side On Resistance vs. Junction Temperature

Figure 15 through Figure 18 are measured on a 2.5-inch × 2.5-inch × 0.062-inch FR4 board with 4 layers and 2 oz. copper, a 0.44-µH output inductor and a DCR of 0.32 mΩ.

TPS56121 highoc13_lusah4.png Figure 13. High-Side Overcurrent Threshold vs. Junction Temperature
TPS56121 eff12v15.png Figure 15. Efficiency vs. Load Current (VVIN = 12 V)
TPS56121 soa12_lusah4.png Figure 17. Output Current vs. Ambient Temperature
(VVIN = 12 V)
TPS56121 pg14_lusah5.png Figure 14. Power Good Threshold Voltage vs. Junction Temperature
TPS56121 eff05v16.png Figure 16. Efficiency vs. Load Current (VVIN = 5 V)
TPS56121 soa05_lusah4.png Figure 18. Output Current vs. Ambient Temperature
(VVIN = 5 V)