TPS3123 Active-low, push-pull, supply voltage supervisor with watchdog timer & manual reset |

This product has been released to the market and is available for purchase. For some products, newer alternatives may be available.
Active-low, push-pull, supply voltage supervisor with watchdog timer & manual reset


Recommended alternative parts

  • TPS3850  -  A window detector with built-in window watchdog timer for overvoltage and undervoltage detection
  • TPS3851  -  Voltage supervisor with standard watchdog timer that offers high accuracy (0.8%) and low IQ (10 µA)
  • TPS3431  -  A standalone watchdog timer with no built-in voltage monitoring feature
  • TPS3823  - The device has the SAME FUNCTIONALITY and PINOUT as the compared device but is NOT an exact equivalent.   Threshold voltages 2.5 and above


The TPS312x family of ultralow voltage processor supervisory circuits provides circuit initialization and timing supervision, primarily for DSP and processor-based systems.

During power-on, RESET is asserted when the supply voltage (VDD) becomes higher than 0.75 V. Thereafter, the supply voltage supervisor monitors VDD and keeps RESET output active as long as VDD remains below the threshold voltage (VIT). An internal timer delays the return of the output to the inactive state (high) to ensure proper system reset. The delay time, td = 180 ms, starts after VDD has risen above the threshold voltage (VIT).

When the supply voltage drops below the threshold voltage (VIT), the output becomes active (low) again. No external components are required. All the devices of this family have a fixed-sense threshold voltage (VIT) set by a high precision internal voltage divider.

The TPS3123/5/6/8 devices incorporate a manual reset input, MR. A low level at MR causes RESET to become active. The TPS3124 devices do not have the input MR, but include a high-level output RESET same as the TPS3125 and TPS3126 devices. In addition, the TPS3123/4/8 have a watchdog timer that needs to be triggered periodically by a positive or negative transition at WDI. When the supervising system fails to retrigger the watchdog circuit within the time-out interval ttout= 0.8 s, RESET output becomes active for the time period (td). This event also reinitializes the watchdog timer.

The circuits are available in a 5-pin SOT23-5 package. The TPS312x devices are characterized for operation over a temperature range of –40°C to +85°C.


  • Minimum Supply Voltage of 0.75 V
  • Supply Voltage Supervision Range:
    • 1.2 V, 1.5 V, 1.8 V (TPS312x)
    • 3 V (TPS3125 Devices Only)
    • Other Versions on Request
  • Power-On Reset Generator With Fixed Delay Time of 180 ms
  • Manual Reset Input (TPS3123/5/6/8)
  • Watchdog Timer Retriggers the RESET Output at VDD ≥ VIT
  • Supply Current of 14 µA (Typ)
  • Small SOT23-5 Package
  • Temperature Range of –40°C to +85°C
  • Reset Output Available in Push-Pull (Active Low and High) and Open-Drain (Active-Low)


Compare all products in Supervisor & reset ICs Email Download to Excel
Part number Order Threshold voltage 1 (Typ) (V) Number of supplies monitored VCC (Max) (V) VCC (Min) (V) Output driver type/reset output Time delay (ms) Features Rating Operating temperature range (C) Watchdog timer WDI (sec)
TPS3123 Order now 1.08
1     3.3     0.75     Active-low
180     Active-low enable
Manual reset
Watchdog timer    
Catalog     -40 to 85     1.4    
TPS3124 Samples not available 1.08
1     3.3     0.75     Active-high
180     Watchdog timer
Dual output    
Catalog     -40 to 85     1.4    
TPS3128 Samples not available 1.14
1     3.3     0.75     Active-low
180     Active-low enable
Manual reset
Watchdog timer    
Catalog     -40 to 85     1.4