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ZSSC1956 Lead-Acid Battery Sensor / Monitor for Automotive


The ZSSC1956 is a dual-channel ADC with an embedded microcontroller for battery sensing/management in automotive, industrial, and medical systems. One of the two input channels measures the battery current IBAT via the voltage drop at the external shunt resistor. The second input channel measures the battery voltage VBAT and the temperature. An integrated flash memory is provided for customer-specific software; e.g., dedicated algorithms for calculating the battery state. During Sleep Mode (e.g., engine is off), the system makes periodic measurements to monitor the discharge of the battery. Measurement cycles are controlled by the software and include various wake-up conditions. The ZSSC1956 is optimized for ultra-low power consumption and draws only 100µA or less in Low-Power Mode.

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Hi, I’m Josh, and for today’s EEWeb Tech Lab, we will be reviewing IDT’s ZSSC1956, their automotive intelligent battery sensor, a battery monitor for lead acid batteries. This intelligent sensor comes with an embedded microcontroller for greatest flexibility. The device integrates multiple ECU functions into a single package: a high voltage circuit, sigma delta ADCs, analog input stage, digital filtering, and a LIN transceiver. An ARM M0 processor with 96kB flash memory is embedded with access to all sensor peripherals, ready for your firmware code. The ADC’s can measure lead acid battery voltage and current at a rate of 1 kHz or more and resolution of up to 18 bits with no missing codes while concurrently measuring temperature.

Simultaneous measurement of voltage and current allows for inner resistance calculations for battery state of health estimation. Using a shunt, this device is capable of measuring, charging, and discharging battery current with a huge dynamic range from milliamps to thousands of amps. Accumulator registers allow accurately calculating state of charge even in operating modes when the microcontroller is asleep.

Here we have the board. The chip itself is actually hidden inside this holder so you can’t really see it, but it’s actually a 5 by 5 by .8mm QFN package so it’s very, very small. It’s also very low power where you have multiple wake-up modes for varying levels of energy savings versus performance needs. Included in this is the LIN-UART communication as previously stated. There are the three different boards here and they each serve a different function. We’ve got the comm board here, which is how I connect to the board itself, this is the evaluation board where it basically has all the hardware, and all the pin outs to test the device itself.

This is the shunt board. This shunt board just simulates having the lead acid battery. It fakes the response of a battery so you don’t need to actually have a 12-volt battery up here. Now with all these things using this USB interface, you can actually go and directly do some testing with the GUI. As we look at the GUI, there are a couple of different things you can see here. You see the input stimuli, which you have persistent and transient inputs then you have the graph outputs. If you want to do a persistent test, you just click start. It takes a moment and then it starts and you’ll see the lines starting to come in from the right. All of these lines are going to be pretty stable because it’s a persistent stimuli. You can make some changes to the current if you like, and you can see it changing and certain things like the external and internal temperature will change with time as the environment changes.

To make things more interesting, you can go over to transient, first have to stop here, go to transient and then once you go over to transient, you hit start. It’ll restart and here you’ll have some ramping of the voltage from 6 to 18v of current from negative 2 to 2 amps, the temperature and all those sorts of things. And so you’re seeing coming across the screen as well. At the very end, you can save the measured data to file down here and you select that. Then you can use all that information and look at it for further analysis when you’re done with all the testing.

With the ZSSC1956, you can constantly monitor the most important aspects of your battery’s performance in a very small form factor. In low power mode, it only draws one hundred microamps, so this information and management comes with practically zero effect on the performance of the system. The ZSSC1956 isn’t just for automotive applications but also for industrial or medical systems that use lead acid batteries. To find out more information and to see how this can fit in your next application, go to