Automotive Camera Buck Regulator AWK6943 and BT1433 Under Three Operating Conditions

A camera module in a vehicle sees three quite different supply conditions between the moment the key turns to ACC and the moment the car is locked after shutdown. During cold crank the input is pulled far down; in steady operation what matters is efficiency and ripple; after the vehicle is locked the module still has to keep a wake-up circuit and a serializer alive on standby current. Choosing a buck regulator comes down to how much margin the part leaves in each of those three states.

Two domestic synchronous bucks sit in front of us. AWK6943 from Analogwin and BT1433 from BATELAB. Both deliver 3A, both switch at 410kHz, both come in a 3mm × 3mm QFN-8 with integrated high-side and low-side FETs, and on the datasheet they look almost interchangeable. Put them on an automotive camera rail and the differences concentrate in three places.

Input floor differs by one volt at power-up

In a 12V system the battery terminal is dragged low during a cold crank at low temperature, and the harness adds another drop on top, leaving very little input headroom for the buck stage. AWK6943 specifies a continuous input range of 3.0V to 36V; BT1433 specifies 4V to 36V. The ceiling is the same, the floor is one volt apart.

At room temperature on the bench that volt shows nothing. During the tens of milliseconds of a cold crank it changes the picture. The downstream rail is usually 3.3V for the image sensor, and once the input falls below 4V, BT1433 is already sitting on its operating boundary while AWK6943 still has 1V in hand. The undervoltage lockout thresholds point the same way, with BT1433's UVLO rising threshold around 3.5V while AWK6943 sits lower. Camera modules are often the first loads to drop during a vehicle cold crank, so the input floor decides directly whether the module holds its rail through the low-voltage window.

Dark current differs by an order of magnitude after shutdown

After the vehicle is locked the camera module is not fully off. The wake-up circuit, the serializer and some memory keep running on the converted always-on rail. That standby current drains the battery continuously, and what looks like a few milliamps becomes the difference between starting normally and not starting after a few days parked.

The two parts separate sharply here. AWK6943 has a typical operating quiescent current of 30μA converting 12V to 3.3V, 20μA when not switching, and 8μA in shutdown. BT1433 specifies 0.5mA typical and 0.7mA maximum quiescent current, with the same 8μA shutdown current. That is 0.5mA against 30μA, a full order of magnitude, and the module that uses AWK6943 is the one that draws less once the ignition is off.

One caveat is fair. The quiescent current of the two parts is measured under different conditions: AWK6943 quotes 12V to 3.3V at no load, while BT1433 quotes enable high with a 1V feedback condition. For an automotive application what actually matters is the magnitude of current leaving the battery after shutdown, and the 30μA class is the more comfortable one for long idle periods.

AEC-Q100 is the gate into the bill of materials

For body electronics, many OEMs write AEC-Q100 into the bill of materials directly. The AWK6943 datasheet states on its first page that the part is intended for automotive systems covering cockpit and ADAS, and lists AEC-Q100. The BT1433 datasheet carries no automotive qualification marking; its application list is consumer electronics, multi-function printers and distributed power systems.

For a camera module maker this item is not a question of parameter margins but of whether the part can enter the list at all. When a project explicitly requires automotive-qualified devices, the selection is already decided at that point. Conversely, if the product is consumer or industrial and carries no automotive qualification requirement, this item imposes no constraint.

Where BT1433 still holds its ground

The differences are not one-directional. BT1433 is wider than AWK6943 in two respects.

The first is external clock synchronization. The EN/SYNC pin of BT1433 accepts an external clock from 200kHz to 2.2MHz, which lets the switching frequency align with the system clock or steer away from a particular band. AWK6943 does not support external synchronization and its switching frequency is fixed around 410kHz. Cameras and serializers are sensitive to EMI, so if the system needs synchronization to suppress interference in a given band, this capability has value.

The second is conduction loss. BT1433 specifies 85mΩ typical high-side and 55mΩ low-side on-resistance; AWK6943 specifies 105mΩ and 65mΩ. At the full 3A load the loss difference is in the fraction-of-a-watt range, which shifts the thermal margin slightly. BT1433 also comes in an ESOP8 package in addition to QFN-8, an extra option where a larger thermal pad is needed.

AWK6943 vs BT1433 full parameter comparison

The three conditions added up

Put the three operating conditions and the qualification gate together and the conclusion is direct.

If the product goes into the body, into a camera module, and has to clear an automotive bill of materials, take AWK6943. Its input floor is lower, leaving more margin downstream during cold crank; its quiescent current is an order of magnitude lower, giving the dark current budget room; and the datasheet states AEC-Q100, so no extra qualification work is needed to enter the list. Those three points are exactly what an automotive camera cares about.

If the product is consumer or industrial, needs no automotive qualification, and the system relies on external clock synchronization to avoid an interference band, BT1433 is the better fit. Its on-resistance is lower, its full-load loss smaller, and the ESOP8 option adds a package with better heat spreading.

Both parts are domestic supply. Samples and datasheets come through the distributor channel, and cost and lead time leave more room than imported alternatives. For a specific camera module, the final choice still has to be weighted against the upstream battery voltage range, the module standby current budget and the OEM qualification requirement.

AWK6943 and related synchronous buck regulators are available from Shenzhen Manduic Technology Co., Ltd., an authorized distributor of Analogwin, together with complete datasheets, cross-reference comparison and design-in support.

For samples, product datasheets, detailed adaptation solutions or technical support, please contact us:

Tel: +86-150-1290-5940

Email: sales@manduic.com

Website: www.manduic.com