CH217K

Part: CH217 from WCH

Type: USB Current Limit Power Distribution Switch Chip

Description: The CH217 is a USB port power switch chip with an adjustable current limit threshold from 400mA to 2.7A, supporting a supply voltage range of 2.7V to 5.5V, and featuring overcurrent, overtemperature, and undervoltage protection.

Operating Conditions:

• Supply voltage: 2.7–5.5 V
• Operating temperature: -40 to 85 °C
• Current limit threshold: 400mA–2.7A

Absolute Maximum Ratings:

• Max supply voltage: 6 V
• Max junction/storage temperature: 150 °C

Key Specs:

• Power Switch On-Resistance (Ron): 70 mΩ (Typ, Iout=500mA)
• Current Limit Threshold (Iset): 2 A (Typ, Rset=30KΩ)
• VOUT to GND Short-Circuit Current (Ishort): 1.2 A (Typ, Rset=30KΩ)
• Quiescent Operating Current (Iq): 50 μA (Typ, EN#=Low Level)
• Shutdown Current (Isd): 0.1 μA (Typ, EN#=High Level)
• Undervoltage Lockout Voltage (Vuvlo): 2.2 V (Typ, VIN Rising Edge)
• Overtemperature Protection Threshold (Tsd): 155 °C (Typ, Temperature Rising Edge)
• Delay from Fault Detection to FLAG# Pin Output Active (Tdly): 8 mS (Typ)

Features:

• Built-in power switch, typical 70mΩ on-resistance.
• Current limit threshold adjustable via external resistor, supporting 400mA ~ 2.7A, typical error ± 10%.
• Supports supply voltage 2.7V ~ 5.5V.
• Fast current limit protection during output short circuit.
• Low power consumption, typical 50μA quiescent operating current.
• Typical shutdown current less than 1μA, no reverse current during shutdown.
• SOT23-6 package.

Applications:

• Power control of ports in computers
• USB hosts
• USB HUBs
• Chargers

Package:

• SOT23-6 (Small 6-pin SMT)

• Built-in power switch, typical 70m Ω on-resistance.
• Current limit threshold adjustable via external resistor, supporting 400mA ~ 2.7A, typical error ± 10%.
• Supports supply voltage 2.7V ~ 5.5V.
• Fast current limit protection during output short circuit.
• Low power consumption, typical 50μA quiescent operating current.
• Typical shutdown current less than 1μA, no reverse current during shutdown.
• SOT23-6 package.

CH217 can be used for power control of ports in computers, USB hosts, USB HUBs, chargers, etc.

The figure below shows an application for independent power distribution control of each port in a HUB. The EN# pin is controlled by the PWREN# signal of the HUB chip CH335 or CH334. The FLAG# pin can generate overcurrent or overtemperature alarm signals to notify the HUB controller and the computer. CH334/5 already has built-in pull-up resistors. In the figure, Rset is 56K, setting the current limit threshold to approximately 1A. The actual value should be selected based on the power supply capacity to achieve protection.

Capacitor C8 capacity can be selected as needed, C4/C5/C6/C7 typical value can be 150μF.

When designing the PCB, the actual operating current carrying capacity needs to be considered. The PCB traces for VIN (+5V) and VOUT (VBUS*) should be as wide as possible. If vias are used, multiple vias are recommended, at least two or more in parallel.

4