UC3843B
Full part number: UC3843BN
Key datasheet specifications and the closest alternatives, ranked by parametric similarity and grounded in the manufacturer datasheet.
This datasheet covers the UC3842B through UC3845B family of high-performance current-mode PWM controllers designed for off-line and DC-to-DC applications. It provides precise frequency control up to 500 kHz with automatic feed-forward compensation and latching PWM for cycle-by-cycle current limiting. Key parameters include a supply voltage range of 16V (on)/10V (off) or 8.5V/7.9V depending on the part, an oscillator frequency typical of 250 kHz, and output currents capable of sourcing or sinking up to 1 A peak.
Datasheet parameters
| Parameter | Min | Typ | Max | Conditions |
|---|---|---|---|---|
| quiescent current | — | 12 mA | 17 mA | VPIN2 = VPIN3 = 0V |
| output voltage | 4.9 V | 5 V | 5.1 V | Tj = 25°C Io = 1mA |
| output current | 2 mA | 12 mA | — | VPIN2 = 2.7V VPIN1 = 1.1V |
| supply voltage range | 8.5 V | 10 V | 11.5 V | X842B/4B |
| switching frequency | 52 kHz | — | 250 kHz | |
| gain bandwidth | 700 kHz | 1 MHz | — | TJ = 25°C |
| operating temperature | 0 °C | — | 70 °C | |
| power dissipation | — | — | 1.25 W | |
| standby current | — | 300 µA | 500 µA | Vi = 6.5V for UCX843B/45B |
| psrr | 70 dB | — | — | 12V ≤ Vi≤ 25V |
| dropout voltage | — | 1.6 V | — | |
| rise time | — | 50 ns | 150 ns | Tj = 25°C CL = 1nF (2) |
| fall time | — | 50 ns | 150 ns | Tj = 25°C CL = 1nF (2) |
| output noise voltage | — | 50 µV | — | 10Hz ≤ f ≤ 10KHz Tj = 25°C (note 2) |
| zener voltage | 30 V | 36 V | — | Ii = 25mA |
| output count | — | 1 | — |
Closest matches to UC3843B
Frequently asked questions
What is the dropout voltage of the UC3843BN?
The dropout voltage is 1.6 V.
What is the fall time of the UC3843BN at Tj = 25°C with CL = 1nF?
The fall time is 50 ns at Tj = 25°C with CL = 1nF.
What is the gain bandwidth of the UC3843BN at TJ = 25°C?
The gain bandwidth is 1 MHz at TJ = 25°C.
What is the maximum operating temperature for the UC3843BN?
The maximum operating temperature is 70 °C.
What is the output count for the UC3843BN?
The output count is 1.
What is the output current when VPIN2 = 2.7V and VPIN1 = 1.1V?
The output current is 12 mA.
What is the output noise voltage of the UC3843BN?
The output noise voltage is 50 µV at 10Hz ≤ f ≤ 10KHz Tj = 25°C (note 2).
What is the output voltage at Tj = 25°C Io = 1mA?
The output voltage is 5 V at Tj = 25°C Io = 1mA.