SPRAD21I May 2022 – September 2025 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP , AM62A1-Q1 , AM62A3 , AM62A3-Q1 , AM62A7 , AM62A7-Q1 , AM62D-Q1 , AM62P , AM62P-Q1
LVCMOS (SDIO) inputs have slew rate requirements specified (as part of the electrical specifications). Connecting slow ramp input (signal) directly to the LVCMOS (SDIO) inputs is not recommended. There can be long-term reliability issues (concerns) associate with the input buffer if the applied input (signal) spends more time in the voltage region between VIHSS and VILSS. The transition time allowed (recommended) is <1000ns. The slew rate has frequency dependency. A maximum slew of 1000ns is recommended when the signals toggle rate is not high (non-frequency dependent limit). When IO is operating at 1.8V (as an example), the non-frequency dependent limit of 1.8E+6V/s becomes the larger value when the signal toggle rate is < 100kHz. The frequency dependent limit of 18fV/s (f = toggle frequency of the input signal in Hz) becomes the larger value when the signal toggle rates is >100kHz. When a slow ramp input is applied (when the input is at mid-supply), shoot-through current can flow from VDD through the partially turned on P-channel transistor and the partially turned on N-channel transistor to VSS. Accumulated exposure to slow ramp input results in IO performance, board performance or processor reliability concerns.
Connecting a large capacitor directly at the LVCMOS (SDIO) outputs is not recommended. LVCMOS (SDIO) output buffers are not designed to drive large capacitive loads. When LVCMOS (SDIO) type IOs are configured as output and a capacitor is connected at the output, the recommendation is to follow the processor-specific data sheet recommendations for the allowed capacitor value or add series resistor to limit the IO current draw. The recommendation is to perform simulations to finalize the capacitor value.