UC3844B
Full part number: UC3844BD1013TR
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 UC3844B does
The UC384xB family of control ICs provides high-performance current mode PWM control for off-line or DC to DC schemes with a minimal external parts count. These devices feature an internally trimmed oscillator operating up to 500 kHz, an error amplifier with 1 MHz unity gain bandwidth, and a reference output of 5.0 V. The family includes variants with under-voltage lockout thresholds ranging from 7.9 V to 16 V and maximum duty cycles approaching 100%. They are typically used to drive N-Channel MOSFETs in switching power supplies, offering cycle-by-cycle current limiting and automatic feed-forward compensation to ensure precise duty cycle control.
Datasheet parameters
| Parameter | Min | Typ | Max | Conditions | Source |
|---|---|---|---|---|---|
| quiescent current | — | 12 mA | 17 mA | VPIN2 = VPIN3 = 0V; ii; TOTAL STANDBY CURRENT | TI datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| output voltage | 4.9 V | 5 V | 5.1 V | Tj = 25°C Io = 1mA; vref; REFERENCE SECTION | TI datasheet, p. 3 — ORDERING NUMBERS |
| output current | 2 mA | 12 mA | — | VPIN2 = 2.7V VPIN1 = 1.1V; io; ERROR AMP SECTION | TI datasheet, p. 3 — ORDERING NUMBERS |
| supply voltage range | 8.5 V | 10 V | 11.5 V | X842B/4B; UNDER-VOLTAGE LOCKOUT SECTION | TI datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| switching frequency | — | 52 kHz | — | RT = 6.2 kΩ, CT = 1 nF, Tj = 25 °C | TI datasheet, p. 3 — ORDERING NUMBERS |
| gain bandwidth | 700 kHz | 1 MHz | — | TJ = 25°C; ERROR AMP SECTION | TI datasheet, p. 3 — ORDERING NUMBERS |
| operating temperature | 0 °C | — | 70 °C | TI datasheet, p. 3 | |
| power dissipation (abs max) | — | — | 1.25 W | ptot(minidip); ABSOLUTE MAXIMUM RATINGS | TI datasheet, p. 2 — ABSOLUTE MAXIMUM RATINGS |
| standby current | — | 300 µA | 500 µA | Vi = 6.5V for UCX843B/45B; TOTAL STANDBY CURRENT | TI datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| psrr | 60 dB | 70 dB | — | 12V ≤ Vi≤ 25V; psrr; ERROR AMP SECTION | TI datasheet, p. 3 — ORDERING NUMBERS |
| rise time | — | 50 ns | 150 ns | Tj = 25°C CL = 1nF (2); tr; OUTPUT SECTION | TI datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| fall time | — | 50 ns | 150 ns | Tj = 25°C CL = 1nF (2); tf; OUTPUT SECTION | TI datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| output noise voltage | — | 50 µV | — | 10Hz ≤ f ≤ 10KHz Tj = 25°C (note 2); en; REFERENCE SECTION | TI datasheet, p. 3 — ORDERING NUMBERS |
| zener voltage | 30 V | 36 V | — | Ii = 25mA; viz; TOTAL STANDBY CURRENT | TI datasheet, p. 4 — ELECTRICAL CHARACTERISTICS (continued) |
| output count | — | 1 | — | TI datasheet, p. 2 — PIN FUNCTIONS |
Closest matches to UC3844B
Frequently asked questions
What is the fall time (tf) of the output section at Tj = 25°C with CL = 1nF?
The fall time is 50 ns.
What is the gain bandwidth of the UC3844BD1013TR when the junction temperature is 25°C and the error amplifier section is active?
The gain bandwidth is 1 MHz.
What is the operating temperature of the UC3844BD1013TR?
The operating temperature is 70 °C.
What is the output count for the UC3844BD1013TR?
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 specification for the UC3844BD1013TR?
The output noise voltage is 50 µV in the 10Hz ≤ f ≤ 10KHz frequency range at Tj = 25°C.
What is the output voltage at Tj = 25°C Io = 1mA; vref; REFERENCE SECTION?
The output voltage is 5 V at Tj = 25°C Io = 1mA; vref; REFERENCE SECTION.
What is the power dissipation under the ptot(minidip) condition in the ABSOLUTE MAXIMUM RATINGS?
The power dissipation is 1.25 W.
What is the power supply rejection ratio (PSRR) for the error amplifier section when the input voltage is between 12V and 25V?
The PSRR is 70 dB.
What is the quiescent current when VPIN2 = VPIN3 = 0V and ii?
The quiescent current is 12 mA under the condition of TOTAL STANDBY CURRENT with VPIN2 = VPIN3 = 0V and ii.
What is the rise time of the output section at Tj = 25°C with CL = 1nF?
The rise time is 50 ns.
What is the total standby current when Vi = 6.5V for the UCX843B/45B?
The total standby current is 300 µA when Vi = 6.5V for the UCX843B/45B.