UC3843B
Full part number: UC3843BN
Every spec below is cited to the manufacturer datasheet. Compare the closest alternatives, then ask the assistant what it means for your design.
What the UC3843B does
The UC384xB family are high performance current mode PWM controllers designed for off-line or DC to DC fixed frequency control schemes. This family spans the UC3842B, UC3843B, UC3844B, and UC3845B variants, which differ primarily in under-voltage lockout thresholds and maximum duty cycle ranges. Key parameters include a guaranteed 250 kHz oscillator frequency extendable to 500 kHz, a 5.00 V internally trimmed reference, and output currents up to 1 A. These controllers feature automatic feed forward compensation and are typically used to drive N-Channel MOSFETs in switching power supply applications requiring precise duty cycle control with minimal external parts.
Datasheet parameters
| Parameter | Min | Typ | Max | Conditions | Source |
|---|---|---|---|---|---|
| quiescent current | — | 12 mA | 17 mA | VPIN2 = VPIN3 = 0V; ii; TOTAL STANDBY CURRENT | ST datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| output voltage | 4.9 V | 5 V | 5.1 V | Tj = 25°C Io = 1mA; vref; REFERENCE SECTION | ST datasheet, p. 3 — ORDERING NUMBERS |
| output current | 2 mA | 12 mA | — | VPIN2 = 2.7V VPIN1 = 1.1V; io; ERROR AMP SECTION | ST datasheet, p. 3 — ORDERING NUMBERS |
| supply voltage range | 8.5 V | 10 V | 11.5 V | X842B/4B; UNDER-VOLTAGE LOCKOUT SECTION | ST datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| switching frequency | — | 52 kHz | — | RT = 6.2k, CT = 1nF, Tj = 25 °C | ST datasheet, p. 3 — ORDERING NUMBERS |
| gain bandwidth | 700 kHz | 1 MHz | — | TJ = 25°C; ERROR AMP SECTION | ST datasheet, p. 3 — ORDERING NUMBERS |
| operating temperature | 0 °C | — | 70 °C | UC384XB family (Vi = 15V) | ST datasheet, p. 3 |
| power dissipation (abs max) | — | — | 1.25 W | ptot(minidip); ABSOLUTE MAXIMUM RATINGS | ST datasheet, p. 2 — ABSOLUTE MAXIMUM RATINGS |
| standby current | — | 300 µA | 500 µA | Vi = 6.5V for UCX843B/45B; TOTAL STANDBY CURRENT | ST datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| psrr | 60 dB | 70 dB | — | 12V ≤ Vi≤ 25V; psrr; ERROR AMP SECTION | ST datasheet, p. 3 — ORDERING NUMBERS |
| rise time | — | 50 ns | 150 ns | Tj = 25°C CL = 1nF (2); tr; OUTPUT SECTION | ST datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| fall time | — | 50 ns | 150 ns | Tj = 25°C CL = 1nF (2); tf; OUTPUT SECTION | ST datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| output noise voltage | — | 50 µV | — | 10Hz ≤ f ≤ 10KHz Tj = 25°C (note 2); en; REFERENCE SECTION | ST datasheet, p. 3 — ORDERING NUMBERS |
| zener voltage | 30 V | 36 V | — | Ii = 25mA; viz; TOTAL STANDBY CURRENT | ST datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| output count | — | 1 | — | ST datasheet, p. 2 — PIN FUNCTIONS |
Closest matches to UC3843B
Frequently asked questions
What is the fall time (tf) of the output section when Tj = 25°C and CL = 1nF (2)?
The fall time is 50 ns.
What is the gain bandwidth of the UC3843BN error amplifier section at TJ = 25°C?
The gain bandwidth is 1 MHz.
What is the operating temperature for the UC384XB family with Vi = 15V?
The operating temperature is 70 °C.
What is the output count for the UC3843BN?
The output count is 1.
What is the output current of the error amp section when VPIN2 = 2.7V and VPIN1 = 1.1V?
The output current is 12 mA.
What is the output noise voltage of the UC3843BN at a junction temperature of 25°C within the frequency range of 10Hz to 10KHz?
The output noise voltage is 50 µV.
What is the output voltage of the UC3843BN at Tj = 25°C with Io = 1mA in the REFERENCE SECTION?
The output voltage is 5 V.
What is the power dissipation for the UC3843BN in a MiniDIP package under Absolute Maximum Ratings?
The power dissipation is 1.25 W.
What is the power supply rejection ratio (PSRR) for the error amplifier section when Vi is between 12V and 25V?
The PSRR is 70 dB.
What is the total standby current when VPIN2 = VPIN3 = 0V?
The total standby current is 12 mA.
What is the rise time of the output section?
The rise time is 50 ns at Tj = 25°C with CL = 1nF.
What is the total standby current when Vi = 6.5V for UCX843B/45B?
The total standby current is 300 µA when Vi = 6.5V for UCX843B/45B.