Product Overview
UC3842AN Current-Mode PWM Controller, 8-Pin DIP
Condition
New. The photo shows a representative unit from our stock. Same or next business day shipping from our Idaho warehouse. Honest pricing, no nonsense. Online since 1999. We are here for our customers, with a no-hassle satisfaction guarantee.
Product Overview
The top face reads UC3842AN over a Motorola M logo, with a lot line KKHK and a date code 9211, and there is a moulded pin-1 dimple at the corner of the black 8-pin plastic DIP. That marking puts the silicon on this card with Motorola rather than the brand currently in the catalog field, which is why the brand is queued for the owner's glance. The UC384x line is the current-mode PWM controller family used in off-line and DC-to-DC converters; 10 pieces are on the shelf, sold each.
Key Features
- Current-mode PWM controller in an 8-pin plastic DIP, the N package
- Maximum duty cycle up to about 100 percent, which is the hard difference from the UC3844's 50 percent limit, per TI's published UCx84xA data
- Undervoltage lockout 16 V on and 10 V off, the same pair the UC3844 carries, per TI's published UCx84xA data; the low 8.4 V and 7.6 V pair belongs to the 3843 and 3845, not here
- The A revision adds a trimmed oscillator discharge current and the lower start-up current behind this listing's "less than 0.5 mA", per TI
- VCC absolute maximum 30 V from a low-impedance source, output peak current +/-1 A, per TI
- 5.0 V reference trimmed to 2 percent on the 384x line, current-sense threshold about 1.0 V and clamped to 1 V, per TI
- Oscillator usable to 500 kHz, set by external RT and CT, per TI
- 384x leading digits set a 0 C to 70 C temperature grade, per TI's published grade table
- Body marking read from these photos: UC3842AN, Motorola M logo, KKHK, 9211
The figures above are the published UCx84xA numbers for the UC3842A type; no Motorola-era sheet for this exact marking was retrieved, so verify against the maker's published UCx84xA data before designing in.
Applications
- Off-line flyback and forward supplies that need high on-time
- DC-to-DC converter control with pulse-by-pulse current limiting
- Service of 1990s switching supplies built around the UC3842A
- Bench work on current-mode control loops
Frequently Asked Questions
How many should I order?
Order the count the repair calls for; there are 10 on the shelf here, sold each. Shipping is $8 flat rate and free on orders over $28, so small parts like this ship smartest as part of a larger order.
Is this interchangeable with a UC3844?
No. This 3842 runs up to nearly 100 percent maximum duty while the 3844 is internally toggled to about half, so swapping one for the other changes the on-time the supply can reach. Undervoltage lockout is not the difference: both parts carry the same 16 V and 10 V pair.
A 1992 date code, a Motorola M, and a type published for duty to nearly full.
