ZHCSFP1A November 2016 – September 2021 TPS3851
PRODUCTION DATA
NAME | NO. | I/O | DESCRIPTION |
---|---|---|---|
CWD | 2 | I | Programmable watchdog timeout input. The
watchdog timeout is set by connecting a capacitor between this pin
and ground. Connecting via a 10-kΩ resistor to VDD or
leaving unconnected further enables the selection of the preset
watchdog timeouts; see the CWD Functionality section. The TPS3851 determines the watchdog timeout using either Equation 1 or Equation 2 with standard or extended timing, respectively. |
GND | 4 | — | Ground pin |
MR | 3 | I | Manual reset pin. A logical low on this pin issues a RESET. This pin is internally pulled up to VDD. RESET remains low for a fixed reset delay (tRST) time after MR is deasserted (high). |
RESET | 8 | O | Reset output. Connect RESET using a 1-kΩ to 100-kΩ resistor to the correct pullup voltage rail (VPU). RESET goes low when VDD goes below the undervoltage threshold (VITN). When VDD is within the normal operating range, the RESET timeout-counter starts. At completion, RESET goes high. During startup, the state of RESET is undefined below the specified power-on-reset (POR) voltage (VPOR). Above POR, RESET goes low and remains low until the monitored voltage is within the correct operating range (above VITN+VHYST) and the RESET timeout is complete. |
SET1 | 5 | I | Logic input. Grounding the SET1 pin disables the watchdog timer. SET1 and CWD select the watchdog timeouts; see the SET1 section. |
VDD | 1 | I | Supply voltage pin. For noisy systems, connecting a 0.1-μF bypass capacitor is recommended. |
WDI | 6 | I | Watchdog input. A
falling edge must occur at WDI before the timeout (tWD)
expires. When the watchdog is not in use, the SET1 pin can be used to disable the watchdog. WDI is ignored when RESET or WDO are low (asserted) and when the watchdog is disabled. If the watchdog is disabled, WDI cannot be left unconnected and must be driven to either VDD or GND. |
WDO | 7 | O | Watchdog output. Connect WDO with a 1-kΩ to 100-kΩ resistor to the correct pullup voltage rail (VPU). 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. |