Espressif Systems ESP Faq page 182

Chapter 5. Hardware related
5.3.52 How to design an automatic download circuit based on the ESP32 series chip?
• You can refer to the hardware design of the automatic download circuit in the
5.3.53 Which crystal oscillator should be used on the ESP8266 chip?
• The ESP8266 chip requires the 26 MHz crystal oscillators to start the chip. The crystal precision should be
±10 PPM. For details, please refer to
5.3.54 Do the ESP32-C2, ESP32-C3 and ESP32-C6 chips support external PSRAM
chips?
• ESP32-C2, ESP32-C3, and ESP32-C6 do not support external PSRAM chips.
5.3.55 When the ESP32-C3 is powered by a battery, it may fail to start if the supply
voltage gradually decreases, for example, when the battery is fully discharged and
then recharged. In such cases, the solution could only be disconnecting the battery
from the ESP32-C3 and reconnect a fully charged battery, or to connect a voltage
regulator diode between the 3.3 V pin and the EN pin to ensure the chip starts
properly. What is the root cause of this situation? Is there an optimal solution?
• Root cause: When powering up and resetting the ESP32-C3 chip, the CHIP_EN pin needs to meet the power-
up timing specifications outlined in the
the battery discharge and power-up process are relatively slow, ESP32-C3 may not be fully reset, resulting in
certain units of the chip being in an uncertain state.
• Solution: Currently, if using battery power or energy storage systems, this issue can be addressed by adjusting
RC component values, using voltage divider circuits with two resistors, or using a reset IC, which is a more
commonly used approach. For detailed information regarding RC component values and related resistors,
please refer to ESP32-C3 Family Hardware Design
5.4 RF Related
5.4.1 Does the RF performance of an ESP32 module degrade if it runs with a 2.8 V sup-
ply?
Yes, its RF performance may become unstable. It is recommended to follow the suggested operating
voltage range specified in the
Espressif Systems
《ESP8266 Hardware Design
ESP32-C3 datasheet
Guidelines.
module's datasheet.
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ESP32-DevKitC V4
Guidelines》.
or ESP32-C3 hardware design
schematic.
guidelines. If
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