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Revision 2.3

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AS8525

Datasheet - Detailed Descr i p ti on

7 Detailed Description

The following modules are described in detail under this section:



Programmable-Gain Amplifier (PGA) / Current-Sense Amplifier (CSA)



Voltage Attenuator



Voltage Regulators (LDO & ALDO)



LIN Transceiver



Temperature Monitor/Limiter



VSUP Under-Voltage Reset



RESET



VCC Under-Voltage Reset



Window Watchdog (WWD)



Timeout Watchdog (TWD)

7.1 Programmable-Gain Amplifier (PGA) / Current-Sense Amplifier (CSA)

The current-sense amplifier primarily serves the purpose of shifting the common-mode level of the signal from around the battery voltage to a low

voltage which is nominally half the regulated supply voltage. The input to the amplifier can be optionally chopped for offset and low-frequency

noise mitigation. As the name indicates, it also provides a programmable gain for the measurement of different battery current ranges which can

be programmed through SPI.

7.2 Voltage Attenuator

A resistive divider is used as a battery voltage attenuator. Like the amplifier, the attenuator can be enabled or disabled through SPI, and in the

device standby mode, we additionally need logic high on MEN pin for enabling. Internal reverse polarity protection is provided for VBAT pin.

Figure 5. Attenuator Implementation

7.3 Voltage Regulators (LDO & ALDO)

The device has two low-dropout voltage regulators, named LDO and ALDO, with one-time programmable 3.3V / 5V voltage outputs. The output

of the LDO is VCC and that of the ALDO is AVCC. The regulated voltage choice is common to both the regulators. The regulators are always ON

except when the device enters the sleep mode or over-temperature shutdown.

The two regulators have inbuilt short-circuit current limitation feature.

The regulators can be temporarily shut down for hard reset of the external circuitry by configuring the device to temporary shutdown mode

through SPI.

The LDO power-up happens when the POR-VSUP event occurs (RESET_VSUP_N switching from low to high), and the ALDO powers up when

POR-VCC event occurs (RESET_VCC_N switching from low to high). The start-up sequence is the same even after a temporary shutdown

phase. The ALDO will be switched off if there is an under-voltage on VCC, that is, when RESET_VCC_N switches back to low.

VBAT

VBAT_DIV

VBAT_DIVN

PD