Understanding D2 Functionality

C

chien94

Please explain what @D2 does.

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D2 is a dual-channel transient-voltage-suppressor (TVS) diode (Würth Elektronik WE-TVS-82400102) placed across the USB data lines to protect against ESD and surge events. Key details:

Table

FeatureSpecification
FunctionESD/surge protection for USB D+ and D– lines
Topology2 channels + common cathode (2 + 1)
Clamping Voltage (typ.)7.7 V at 1 A (Transmission Line Pulsing)
Peak Pulse Current (8/20 µs)6 A
PackageSOT-23-6L
Operating Temperature–55 °C to +125 °C
ComplianceIEC 61000-4-2, ‑4, and ‑5
DatasheetDatasheet (PDF)
By clamping any fast voltage spikes on USB1’s DP and DN nets to ground, this part safeguards the CH340C USB interface and downstream circuitry against electrostatic discharge and other transient overvoltages.
Add TVS diode
Enforce placement
Assign net class
Extract footprint dims
Add series resistor
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Files

Schematic

Layout

3D View

ESP_RX
ESP_RX
SDA
ESP_TX
CAM_PWDN
SDA
GPIO15
CAM_D7
CAM_D7
CAM_D4
GPIO15
GPIO14
CAM_D5
CAM_D3
CAM_RST
CAM_MCLK
ESP_IO0
CAM_D1
CAM_D0
GPIO13
GPIO4
GPIO13
SCL
GPIO12
SCL
GPIO14
CAM_PCLK
SDA
GPIO33
CAM_D6
CAM_RST
GPIO4
GPIO12
CAM_VSYNC
ESP_EN
CAM_D2
CAM_D3
CAM_PWDN
GPIO2
GPIO2
CAM_VSYNC
CAM_PCLK
CAM_MCLK
CAM_D5
SCL
CAM_PCLK
CAM_D4
GPIO33
ESP_EN
CAM_D1
ESP_TX
CAM_HSYNC
ESP_EN
CAM_D2
CAM_HSYNC
CAM_PWDN
ESP_IO0
CAM_D6
CAM_D0
C4
Capacitance
10uF
C18
Capacitance
10uF
C17
Capacitance
10uF
C16
Capacitance
0.1uF
C7
Capacitance
0.1uF
C15
Capacitance
10uF
C8
Capacitance
10uF
C6
Capacitance
0.1uF
C10
Capacitance
0.1uF
C12
Capacitance
0.1uF
C14
Capacitance
0.1uF
C19
Capacitance
0.1uF
C11
Capacitance
10uF
C13
Capacitance
15pF
+3V3
R8
Resistance
4.7kΩ
+3V3
R1
Resistance
10kΩ
+3V3
+3V3
+5V
J3
R5
Resistance
1kΩ
+3V3
+2V8
+2V8
+3V3
+3V3
+1V2
+1V2
+3V3
+3V3
R6
Resistance
4.7kΩ
R7
Resistance
4.7kΩ
+3V3
+3V3
J1
ESP1
RST
U3
BOOT
U2
OV2640

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