SLVSDK1C May   2016  – September 2017 TPS22990

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 = 3.3 V
    7. 7.7 Switching Characteristics
    8. 7.8 Typical 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 On and Off Control
      2. 9.3.2 Adjustable Rise Time
      3. 9.3.3 Power Good (PG)
      4. 9.3.4 Quick Output Discharge (QOD) (TPS22990 Only)
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Input to Output Voltage Drop
      2. 10.1.2 Input Capacitor
      3. 10.1.3 Thermal Consideration
      4. 10.1.4 PG Pull Up Resistor
      5. 10.1.5 Power Sequencing
      6. 10.1.6 Standby Power Reduction
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Managing Inrush Current
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9 Detailed Description

9.1 Overview

The TPS22990 device is a single channel load switch with a controlled adjustable turnon and integrated PG indicator. The device contains an N-channel MOSFET that can operate over an input voltage range of 0.6 V to 5.5 V and can support a maximum continuous current of 10 A. The wide input voltage range and high current capability enable the devices to be used across multiple designs and end equipment. 3.9-mΩ On-resistance minimizes the voltage drop across the load switch and power loss from the load switch.

The controlled rise time for the device greatly reduces inrush current caused by large bulk load capacitances, thereby reducing or eliminating power supply droop. The adjustable slew rate through CT provides the design flexibility to trade off the inrush current and power up timing requirements. Integrated PG indicator notifies the system about the status of the load switch to facilitate seamless power sequencing.

During shutdown, the device has very low leakage current, thereby reducing unnecessary leakages for downstream modules during standby. The TPS22990 has an optional 218-Ω On-chip resistor for quick discharge of the output when switch is disabled.

9.2 Functional Block Diagram

TPS22990 block_diagram_01_slvsdk1a.gif

9.3 Feature Description

9.3.1 On and Off Control

The ON pin controls the state of the load switch. Asserting the pin high enables the switch. The minimum voltage that guarantees logic high is 1.2 V. This pin cannot be left floating and must be tied either high or low for proper functionality.

9.3.2 Adjustable Rise Time

The TPS22990 has controlled rise time for inrush current control. A capacitor to GND on the CT pin adjusts the rise time. Without any capacitor on the CT, the rise time is at its minimum for fastest timing. The voltage on the CT pin can be as high as 15 V; therefore the minimum voltage rating for the CT capacitor must be 25 V for optimal performance. An approximate equation for the relationship between CT, VIN and rise time when VBIAS is set to 5 V is shown in Equation 1. As shown in Figure 35, rise time is defined as from 10% to 90% measurement on VOUT.

Equation 1. TPS22990 Equation_1_SLVSDK1A.gif

where

  • tR is the rise time (in µs)
  • VIN is the input voltage (in V)
  • CT is the capacitance value on the CT pin (in pF)

Table 1 contains rise time values measured on a typical device. Rise times shown below 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 vs CT Capacitor

CT (pF) Rise Time (µs) at 25°C
CL = 0.1 uF, CIN = 1 uF, RL = 10 Ω, VBIAS = 5 V
VIN = 5 V VIN = 3.3 V VIN = 1.8 V VIN = 1.05 V VIN = 0.6 V
0 30.5 24.8 17.5 12.6 9.5
220 44.6 34 22.7 15.8 11.4
470 56.6 42.2 27.1 18.8 13.2
1000 85 61.1 38.9 25.2 17.9
2200 154.6 107 64.7 40.9 27.7
4700 284.6 193.5 114.4 72.8 48.1
10000 598.5 404.8 233.2 146.9 98.6

9.3.3 Power Good (PG)

The TPS22990 has a power good (PG) output signal to indicate the gate of the pass FET is driven high and the switch is on with the On-resistance close to its final value (full load ready). The signal is an active high and open drain output which can be connected to a voltage source through an external pull up resistor, RPU. This voltage source can be VOUT from the TPS22990 or another external voltage. VBIAS is required for PG to have a valid output. Equation 2 below shows the approximate equation for the relationship between CT, VIN and PG turnon time (tPG,ON) when VBIAS is set to 5 V.

Equation 2. TPS22990 Equation_9_SLVSDK1.gif

where

  • tPG,ON is the PG turnon time (in µs)
  • VIN is the input voltage (in V)
  • CT is the capacitance value on the CT pin (in pF)

Table 2 contains PG turnon time values measured on a typical device.

Table 2. PG Turnon Time vs CT Capacitor

CT (pF) Typical PG turnon time (us) at 25°C
CL = 0.1 uF, CIN = 1 uF, RL = 10 Ω, VBIAS = 5 V, RPU = 10 kΩ
VIN = 5 V VIN = 3.3 V VIN = 1.8 V VIN = 1.05 V VIN = 0.6 V
0 151.9 144.4 137.5 133.9 131.3
220 177.7 164.6 153.3 147.1 143.5
470 200.9 183.2 167.4 159.2 154.4
1000 257.2 227.8 202.5 189.5 181.3
2200 390.6 332.3 282.4 257.1 241.6
4700 636.4 525.6 429.8 382.7 353.3
10000 1239 999.8 792.4 689.4 627.4

9.3.4 Quick Output Discharge (QOD) (TPS22990 Only)

The TPS22990 family includes an optional QOD feature. When the switch is disabled, a discharge resistor is connected between VOUT and GND. This resistor has a typical value of 218 Ω and prevents the output from floating while the switch is disabled.

9.4 Device Functional Modes

Table 3 shows the function table for TPS22990.

Table 3. Function Table

ON VIN to VOUT OUTPUT DISCHARGE (1)
L OFF ENABLED
H ON DISABLED
(1) This feature is in the TPS22990 only (not in TPS22990N).