COSINE Tier-1 distributor Jarwey｜COS3842BD PWM controller for the adapter, COS6501 for the isolated CAN rail
Jarwey is a Tier-1 distributor of COSINE—selection support, datasheets, sampling and small batch, lead-time coordination.
An isolated transceiver rail and an adapter power stage do not share a controller. The CAN, RS-485, RS-232, SPI, or I2C side is a small, low-standby push-pull transformer driver: COS6501. Move to COS6505B only when that same isolated interface is being checked in the SN6505B class. The adapter, EV-charger, or external-FET Buck / Boost / Flyback / Forward stage is a peak-current PWM controller: COS3842BD.
The UC3842 versus SG3525 mode table, the SN6501 versus SN6505B package note, and the dropout-heat split between COS3842BD and the 3 A / 7.5 A LDOs already exist. This note only assigns the two rails. Request the datasheet from Jarwey.
Which rail gets which part
| What this rail powers | Part | Bounds on the product page | Package | Search anchor (verify) | Page |
|---|---|---|---|---|---|
| Adapter or EV charger; external-FET Buck, Boost, Flyback, or Forward | COS3842BD | Peak-current PWM controller; controller Vin max 28 V | SOP-8 | UC3842 class | 984 |
| Low-power isolated supply for CAN, RS-485, RS-232, SPI, or I2C | COS6501 | Micropower push-pull transformer driver; small size, low standby | SOT-23-5 | SN6501 class | 986 |
| Same isolated interface, evaluated in the SN6505B class | COS6505B | Same family as COS6501; feature split is in the datasheet | SOT-23-6 | SN6505B class | 987 |
COS3842BD is the controller. The power MOSFET stays off-chip. The product page caps controller Vin at 28 V, so a higher power bus stays on the FET and VCC comes from an auxiliary winding or an earlier rail. Gate resistor, current sense, and slope compensation are bench items. Start-up threshold and maximum duty cycle come from the datasheet Jarwey supplies.
COS6501 drives the isolation transformer for the transceiver secondary. The catalog application is the low-power isolated supply for CAN, RS-485, RS-232, SPI, and I2C. COS6505B stays on that interface rail and moves to SOT-23-6. Turns ratio, saturation, leakage, and creepage are set with the project transformer and the datasheet. This note does not assign output current or switching frequency.
Voltage-mode COS3525ADW (Vin max 35 V, WSOP-16, soft-start and sync pin; catalog use is welders and inverters) stays in the PWM controller family note. The SN6501 / SN6505B package split stays in the push-pull driver note. Whether a wide dropout belongs on COS3842BD or on a 3 A / 7.5 A LDO is the aux-rail heat note.
Checklist before the BOM line
- Name the load: adapter or charger power stage, or the isolated transceiver secondary. Keep one part for each rail.
- Name the interface: CAN, RS-485, RS-232, SPI, or I2C. Confirm the secondary still fits a micropower push-pull using the datasheet and the transformer table.
- Name the topology: external-FET Buck, Boost, Flyback, or Forward points to COS3842BD. A welder, inverter, or a design that needs the sync pin points to COS3525ADW.
- Feed the controller: COS3842BD Vin max is 28 V. A higher bus goes to the MOSFET. Take chip VCC from an auxiliary source and check undervoltage lockout.
- Second isolated part: open COS6505B when the interface is in the SN6505B class. It is still a transformer driver, so it does not gate the adapter MOSFET.
- Anchors need a bench: UC3842, SN6501, and SN6505B are search anchors. Pinout, start-up voltage, and drive strength come from the datasheet and a sample build.
- Samples and lead time: ask Jarwey for the datasheet, a small-batch build, and the delivery date.
Pages and contact
- COS3842BD peak-current PWM controller
- COS6501 push-pull transformer driver
- COS6505B push-pull transformer driver
Send the power-stage topology, the isolated interface, and the incumbent part number to Jarwey: kerry.w@jarwey.cn · Contact. Datasheets, selection, samples, small batch, and lead-time coordination.
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