AS8506 datasheet(23/89 Pages) AMSCO

23 / 89 page

ams Datasheet, Confidential:2013-Sep [1-00]

AS8506 – 23

Detaile d Desc rip t ion

In case the external temperature sensors are not being used,

then both the inputs must be connected to GND pin through

1k resistor. In the measurement phase, external temperature is

measured through the SAR ADC. Both channels of temperature

will be measured and stored in temp_in1_lsb_reg to

temp_in2_msb_reg.

Internal Temperature Monitor

The internal temperature monitor has two thresholds at Tjwarn

125ºC and Tjshut 135ºC. If the internal temperature exceeds

125ºC, then a warning flag is set in the device (status can be

read through SPI) and the device will continue balancing.

If the internal temperature exceeds 135ºC, then a flag is set in

the device and balancing is stopped; but the device continues

to stay in NORMAL mode for maintaining synchronism. In both

the cases, the microcontroller will be interrupted by a pulse on

CVT_NOK_OUT pin. The balance recovery temperature is 115ºC.

PWM Generator

In the Balance phase of the AS8506, based on the decision made

during the Compare phase, some part of the cell is charged with

the Flyback converter. To drive the external Flyback converter,

AS8506 generates a PWM signal to drive external FET or

Optocoupler or Isolation device.

The frequency and of the PWM generator can be controlled by

timer_cntl_reg register.

PWM frequency is not used for the passive balancing.

RC Oscillator

The AS8506 has a trimable RC oscillator. It is designed to

generate fosc-dig clock for the digital circuit and for the clocking

of the IC. Each oscillator will be trimmed with the process to get

the accuracy to fosc-accy with 5-bit OTP Factory trim code.

DAC for the Reference Generation

AS8506 has a 12-bit DAC to generate the cell reference voltage,

cell threshold low and high voltage. The DAC code is written

into AS8506 with SPI interface from microcontroller. The output

of the DAC is given to one of the inputs of the comparators, to

compare the cell voltages synchronously. Reference for the DAC

is 4.5V, which is internally generated and is available as

reference for temperature inputs on REF_T.

AS8506 датащи(PDF) 23 Page - ams AG