The J111 is an industry-standard, high-speed N-Channel Junction Field-Effect Transistor (JFET) encapsulated in a compact TO-92 plastic through-hole package. Specifically engineered for low-resistance analog switching, chopper circuits, commutators, and audio muting applications, the J111 features an exceptionally low on-state resistance (R_DS(on) < 30>

Specifications

• Brand / Manufacturer: ON Semiconductor / Fairchild / InterFET / Industry Standard
• Part Number: J111
• Transistor Type: N-Channel Symmetrical Depletion-Mode JFET
• Drain-Source Voltage (V_DS): 35V
• Drain-Gate Voltage (V_DG): 35V
• Gate-Source Reverse Breakdown Voltage (V_GSR): -35V
• Gate Current (I_G): 50mA
• Zero-Gate-Voltage Drain Current (I_DSS): Minimum 20mA (Typically 20mA to 100mA+ @ V_DS = 15V, V_GS = 0V)
• Gate-Source Cutoff Voltage (V_GS(off)): -3.0V to -10.0V (at V_DS = 15V, I_D = 1.0µA)
• Static Drain-Source On-Resistance (R_DS(on)): < 30>GS = 0V, I_D = 1.0mA)
• Common-Source Input Capacitance (C_iss): Max 28pF (at V_DS = 0V, V_GS = -10V, f = 1.0MHz)
• Common-Source Reverse Transfer Capacitance (C_rss): Max 5.0pF (at V_DS = 0V, V_GS = -10V, f = 1.0MHz)
• Turn-On Time (t_on): Typically < 4>
• Turn-Off Time (t_off): Typically < 25ns>
• Total Device Dissipation (P_D): 350mW to 625mW (at T_A = 25°C)
• Operating Junction & Storage Temperature: -55°C to +150°C
• Package / Case: TO-92 (3-Pin Through-Hole: Pin 1: Drain, Pin 2: Source, Pin 3: Gate)

Features

• Ultra-Low On-Resistance (R_DS(on) ≤ 30Ω): Minimizes signal attenuation, insertion loss, and harmonic distortion in analog switching paths.
• Extremely Fast Switching Speeds: Fast nanosecond turn-on and turn-off response ensures clean switching without signal degradation or heavy delay.
• High Off-State Isolation: Sub-nanoampere gate and drain cutoff leakage currents ensure complete circuit isolation when turned off.
• Symmetrical Channel Geometry: Drain and Source terminals are fully interchangeable for bidirectional AC and DC signal switching.
• High Breakdown Margin (35V): Accommodates standard ±15V and ±12V analog operational amplifier signal swings without junction clipping.

Common Applications

• Analog Signal Switches & Multiplexers: High-speed, low-loss routing for audio signals, test signals, and instrumentation channels.
• Audio Muting & Anti-Pop Circuits: Pop-free audio output muting during power-up/power-down sequences in amplifiers and DACs.
• Choppers & Sample-and-Hold Stages: Fast charging and holding switches in precision data acquisition and ADC front-ends.
• Current Limiters & Constant Current Sources: Ultra-stable two-terminal constant current regulators when Gate is tied to Source.
• Voltage-Controlled Attenuators: Linear, low-distortion variable resistors (VCR) in AGC circuits and volume controls.

Usage Tips

• Pinout Identification: Looking at the flat marked front face of the TO-92 package with leads pointing downward, the standard pinout is Pin 1: Drain (D), Pin 2: Source (S), and Pin 3: Gate (G).
• Switching Control Voltage: Because the J111 is a depletion-mode device, it is fully ON when V_GS = 0V. To ensure the switch is completely OFF, pull the Gate negative with respect to the source by at least -10V (or beyond the maximum negative peak of the analog AC signal being switched).
• Gate Drive Series Resistor / Diode: When driving the gate from standard logic or discrete transistors, place a series diode or 10kΩ resistor to prevent forward-biasing the Gate-Channel PN junction (V_GS must not exceed +0.7V).
• Constant Current Diode Configuration: To use the J111 as a simple 2-terminal constant current regulator, tie the Gate (Pin 3) directly to the Source (Pin 2); the current flowing through will equal the saturated drain current (I_DSS).

Datasheet