LANGTU L-Series Tri-Mode Silent Keyboard

Connectivity and Modes

The keyboard supports three modes of connectivity: Bluetooth, 2.4G Wireless, and Wired.

Wired Mode

Connect the keyboard using the Type-C cable. Press and hold FN + 5 for 3 seconds to switch to wired mode. The indicator light will be solid pink.

2.4G Mode

Press and hold FN + 4 for 3 seconds to enter 2.4G pairing mode. A quick press will reconnect to a paired device. The indicator light is green, flashes rapidly during pairing, flashes slowly when reconnecting, and is solid green when pairing is successful.

Bluetooth Mode

The keyboard features dual-channel Bluetooth 3.0 and 5.0. Press and hold FN + 1, FN + 2, or FN + 3 for 3 seconds to enter the respective channel pairing mode. A quick press will reconnect to a paired device.

• BT Channel 1: Blue indicator. Flashes rapidly during pairing, slowly when reconnecting, solid blue when paired.
• BT Channel 2: Cyan indicator. Flashes rapidly during pairing, slowly when reconnecting, solid cyan when paired.
• BT Channel 3: Purple indicator. Flashes rapidly during pairing, slowly when reconnecting, solid purple when paired.

System Switching

Switch between operating systems for optimal performance:

• Windows: Press FN + W. The backlight will flash blue 3 times.
• macOS: Press FN + A. The backlight will flash orange 3 times.

Sound & Backlight Modes

The keyboard features dual modes for sound and backlight control.

• Default Backlight Mode: Long press for 5 seconds to switch to Sound Tuning Mode.
• Backlight Mode: Rotate the dial to adjust the backlight mode.
• Sound Mode: Rotate the dial to adjust the volume. A short press mutes the sound.

Common Hotkeys

Access various functions with these key combinations:

• FN + INS: Switch backlight mode.
• FN + ↑ / ↓: Adjust backlight brightness (5 levels).
• FN + ← / →: Adjust backlight speed (5 levels).
• FN + DEL: Turn off backlight.
• FN + WIN: Lock/Unlock Windows key.
• FN + ESC: Long press for 3 seconds to restore factory settings.
• FN + F1: Media Playback (Play/Pause)
• FN + F2: Calculator
• FN + F3: Split Screen
• FN + F4: Siri
• FN + F5: Decrease backlight brightness.
• FN + F6: Increase backlight brightness.
• FN + F7: Previous Song
• FN + F8: Play/Pause
• FN + F9: Next Song
• FN + F10: Mute
• FN + F11: Volume Down
• FN + F12: Volume Up
• FN + CTRL: Turn off LOGO light.

Sleep Settings

The keyboard conserves power with adjustable sleep settings:

• Bluetooth: Turn off backlight after 2 minutes, deep sleep after 10 minutes.
• 2.4G Wireless: Turn off backlight after 2 minutes, deep sleep after 10 minutes.

Current Power Consumption

• Charging Voltage: 4.5 V - 5 V
• Charging Current: 300 MA - 500 MA
• Operating Current: Approx. 60 MA

FCC Warning

This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

NOTE 1: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.

NOTE 2: Any changes or modifications to this unit not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.

The device has been evaluated to meet general RF exposure requirement. The device can be used in portable exposure condition without restriction.