SLVSDD0B May   2016  – September 2017 TPS22975

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics—VBIAS = 5 V
    6. 7.6 Electrical Characteristics—VBIAS = 2.5 V
    7. 7.7 Switching Characteristics
    8. 7.8 Typical DC Characteristics
    9. 7.9 Typical AC Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Adjustable Rise Time
      2. 9.3.2 Quick-Output Discharge (QOD) (Optional)
      3. 9.3.3 Thermal Shutdown
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 ON and OFF Control
      2. 10.1.2 Input Capacitor (CIN) (Optional)
      3. 10.1.3 Output Capacitor (CL) (Optional)
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Inrush Current
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Developmental Support
    2. 13.2 Related Documentation
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Community Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

9 Detailed Description

9.1 Overview

The TPS22975 device is a single-channel, 6-A load switch in an 8-pin SON package. To reduce the voltage drop in high current rails, the device implements an N-channel MOSFET. The device has a configurable slew rate for applications that require a specific rise-time.

The device prevents downstream circuits from pulling high standby current from the supply by limiting the leakage current of the device when it is disabled. The integrated control logic, driver, power supply, and output discharge FET eliminates the need for any external components, which reduces solution size and bill of materials (BOM) count.

9.2 Functional Block Diagram

TPS22975 fbd_02_SLVSDD0.gif

9.3 Feature Description

9.3.1 Adjustable Rise Time

A capacitor to GND on the CT pin sets the slew rate. The voltage on the CT pin can be as high as 15 V; therefore, the minimum voltage rating for the CT capacitor must be 30 V for optimal performance. An approximate formula for the relationship between CT and slew rate when VBIAS is set to 5 V is shown in Equation 1. This equation accounts for 10% to 90% measurement on VOUT and does not apply for CT < 100 pF. Use Table 1 to determine rise times for when CT = 0 pF.

Equation 1. TPS22975 Equation1_SLVSDD0.gif

where

  • SR is the slew rate (in µs/V)
  • CT is the capacitance value on the CT pin (in pF)
  • The units for the constant 26 are µs/V. The units for the constant 0.43 are µs/(V × pF).

Rise time can be calculated by multiplying the input voltage by the slew rate. Table 1 contains rise time values measured on a typical device. Rise times shown in Table 1 are only valid for the power-up sequence where VIN and VBIAS are already in steady state condition before the ON pin is asserted high.

Table 1. Rise Time tR vs CT Capacitor

CT (pF) RISE TIME (µs) 10% - 90%, CL = 0.1 µF, CIN = 1 µF, RL = 10 Ω, VBIAS = 5 V(1)
VIN = 5 V VIN = 3.3 V VIN = 1.8 V VIN = 1.5 V VIN = 1.2 V VIN = 1.05 V VIN = 0.6 V
0 140 105 75 65 60 55 40
220 520 360 215 185 160 140 95
470 970 660 385 330 275 240 155
1000 1750 1190 700 595 495 435 275
2200 3875 2615 1520 1290 1070 940 595
4700 7580 5110 2950 2510 2075 1830 1150
10000 16980 11485 6650 5635 4685 4110 2595
(1) Typical Values at 25°C with a 25-V X7R 10% Ceramic Capacitor on CT

9.3.2 Quick-Output Discharge (QOD) (Optional)

The TPS22975 includes an optional QOD feature. When the switch is disabled, an internal discharge resistance is connected between VOUT and GND to remove the remaining charge from the output. This resistance has a typical value of 230 Ω and prevents the output from floating while the switch is disabled. For best results, it is recommended that the device gets disabled before VBIAS falls below the minimum recommended voltage.

9.3.3 Thermal Shutdown

Thermal shutdown protects the part from internally or externally generated excessive temperatures. When the device temperature triggers TSD (typical 160°C), the switch is turned off. The switch automatically turns on again if the temperature of the die drops 20 degrees below the TSD threshold.

9.4 Device Functional Modes

The Table 2 lists the VOUT pin states as determined by the ON pin.

Table 2. VOUT Connection

ON TPS22975 TPS22975N
L GND Open
H VIN VIN