SBVS301B October   2016  – September 2021 TPS3850

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 Timing Requirements
    7. 6.7 Timing Diagrams
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 CRST
      2. 7.3.2 RESET
      3. 7.3.3 Over- and Undervoltage Fault Detection
      4. 7.3.4 Adjustable Operation Using the TPS3850H01
      5. 7.3.5 Window Watchdog
        1. 7.3.5.1 SET0 and SET1
          1. 7.3.5.1.1 Enabling the Window Watchdog
          2. 7.3.5.1.2 Disabling the Watchdog Timer When Using the CRST Capacitor
          3. 7.3.5.1.3 SET0 and SET1 During Normal Watchdog Operation
      6. 7.3.6 Window Watchdog Timer
        1. 7.3.6.1 CWD
        2. 7.3.6.2 WDI Functionality
        3. 7.3.6.3 WDO Functionality
    4. 7.4 Device Functional Modes
      1. 7.4.1 VDD is Below VPOR ( VDD < VPOR)
      2. 7.4.2 Above Power-On-Reset But Less Than UVLO (VPOR ≤ VDD < VUVLO)
      3. 7.4.3 Above UVLO But Less Than VDD (min) (VUVLO ≤ VDD < VDD (min))
      4. 7.4.4 Normal Operation (VDD ≥ VDD (min))
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 CRST Delay
        1. 8.1.1.1 Factory-Programmed Reset Delay Timing
        2. 8.1.1.2 Programmable Reset Delay-Timing
      2. 8.1.2 CWD Functionality
        1. 8.1.2.1 Factory-Programmed Timing Options
        2. 8.1.2.2 Adjustable Capacitor Timing
      3. 8.1.3 Adjustable SENSE Configuration
      4. 8.1.4 Overdrive on the SENSE Pin
    2. 8.2 Typical Applications
      1. 8.2.1 Design 1: Monitoring a 1.2-V Rail with Factory-Programmable Watchdog Timing
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Monitoring the 1.2-V Rail
          2. 8.2.1.2.2 Meeting the Minimum Reset Delay
          3. 8.2.1.2.3 Setting the Watchdog Window
          4. 8.2.1.2.4 Calculating the RESET and WDO Pullup Resistor
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Design 2: Using TPS3850H01 to monitor a 0.7-V Rail With an Adjustable Window Watchdog Timing
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Meeting the Minimum Reset Delay
          2. 8.2.2.2.2 Setting the Window Watchdog
          3. 8.2.2.2.3 Watchdog Disabled During the Initialization Period
          4. 8.2.2.2.4 Calculating the Sense Resistor
        3. 8.2.2.3 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 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

5 Pin Configuration and Functions

Figure 5-1 DRC Package: TPS3850
3-mm × 3-mm VSON-10
Top View
Table 5-1 Pin Functions
PIN DESCRIPTION
NAME NO. I/O
CRST 4 I Programmable reset timeout pin. Connect a capacitor between this pin and GND to program the reset timeout period. This pin can also be connected by a 10-kΩ pullup resistor to VDD, or left unconnected (NC) for various factory programmed reset timeout options; see the Section 8.1.1 section.
When using an external capacitor, use Equation 3 to determine the reset timeout.
CWD 2 I Programmable watchdog timeout input. Watchdog timeout is set by connecting a capacitor between this pin and ground. Furthermore, this pin can also be connected by a 10-kΩ resistor to VDD, or leaving unconnected (NC) further enables the selection of the preset watchdog timeouts; see the Section 6.6 table.
When using a capacitor, the TPS3850 determines the window watchdog upper boundary with Equation 6. The lower watchdog boundary is set by the SET pins, see Table 8-5 and the Section 8.1.2 section for additional information.
GND 5 — Ground pin
RESET 9 O Reset output. Connect RESET using a 1-kΩ to 100-kΩ resistor to VDD. RESET goes low when the voltage at the SENSE pin goes below the undervoltage threshold (VIT-(UV)) or above the overvoltage threshold (VIT+(OV)). When the voltage level at the SENSE pin is within the normal operating range, the RESET timeout counter starts. At timer completion, RESET goes high. During startup, the state of RESET is undefined below the specified power-on reset voltage (VPOR). Above VPOR, RESET goes low and remains low until the monitored voltage is within the correct operating range (between VIT-(UV) and VIT(+OV)) and the RESET timeout is complete.
SENSE 10 I SENSE input to monitor voltage rail. Connect this pin to the supply rail that must be monitored.
SET0 3 I Logic input. SET0, SET1, and CWD select the watchdog window ratios, timeouts, and disable the watchdog; see the Section 6.6 table.
SET1 6 I Logic input. SET0, SET1, and CWD select the watchdog window ratios, timeouts, and disable the watchdog; see the Section 6.6 table.
VDD 1 I Supply voltage pin. For noisy systems, connecting a 0.1-µF bypass capacitor is recommended.
WDI 7 I Watchdog input. A falling transition (edge) must occur at this pin between the lower (tWDL(max)) and upper (tWDU(min)) window boundaries in order for WDO to not assert.
When the watchdog is not in use, the SET pins can be used to disable the watchdog. The input at WDI is ignored when RESET or WDO are low (asserted) and also when the watchdog is disabled. If the watchdog is disabled, then WDI cannot be left unconnected and must be driven to either VDD or GND.
WDO 8 O Watchdog output. Connect WDO with a 1-kΩ to 100-kΩ resistor to VDD. WDO goes low (asserts) when a watchdog timeout occurs. WDO only asserts when RESET is high. When a watchdog timeout occurs, WDO goes low (asserts) for the set RESET timeout delay (tRST). When RESET goes low, WDO is in a high-impedance state.
Thermal pad — Connect the thermal pad to a large-area ground plane. The thermal pad is internally connected to GND.