Datasheet

Remote High Limit

Remote Diode

Measurement

LM96163 ALERT Pin

Status Register: Remote High

Time

Temperature

Voltage

LM96163

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SNAS433D –JUNE 2008–REVISED MAY 2013

The format of the Remote High limit and T_CRIT limit comparison is programmable. The USF bit found in the

Enhanced Configuration register controls whether comparisons use a signed or unsigned format. The

temperature format used for Remote High and T_CRIT limit comparisons is +255.875 °C to -256 °C.

The three different ALERT modes and TCRIT function will be discussed in the following sections.

ALERT Output as a Temperature Comparator

When the LM96163 is used in a system in which does not require temperature-based interrupts, the ALERT

output could be used as a temperature comparator. In this mode, once the condition that triggered the ALERT to

go low is no longer present, the ALERT is negated (Figure 8). For example, if the ALERT output was activated

by the comparison of LT > LHS, when this condition is no longer true, the ALERT will return HIGH. This mode

allows operation without software intervention, once all registers are configured during set-up. In order for the

ALERT to be used as a temperature comparator, the Comparator Mode bit in the Remote Diode Temperature

Filter and Comparator Mode Register must be asserted. This is not the power-on default state.

Figure 8. ALERT Output as Temperature Comparator Response Diagram

ALERT Output as an Interrupt

The LM96163's ALERT output can be implemented as a simple interrupt signal when it is used to trigger an

interrupt service routine. In such systems it is desirable for the interrupt flag to repeatedly trigger during or before

the interrupt service routine has been completed. Under this method of operation, during the read of the ALERT

Status Register the LM96163 will set the ALERT Mask bit in the Configuration Register if any bit in the ALERT

Status Register is set, with the exception of Busy and RDFA. This prevents further ALERT triggering until the

master has reset the ALERT Mask bit, at the end of the interrupt service routine. The ALERT Status Register bits

are cleared only upon a read command from the master (see Figure 9 ) and will be re-asserted at the end of the

next conversion if the triggering condition(s) persist(s). In order for the ALERT to be used as a dedicated

interrupt signal, the Comparator Mode bit in the Remote Diode Temperature Filter and Comparator Mode

system that uses the ALERT output pin as an interrupt flag:

1. Master senses ALERT low.

2. Master reads the LM96163 ALERT Status Register to determine what caused the ALERT.

3. LM96163 clears ALERT Status Register, resets the ALERT HIGH and sets the ALERT Mask bit in the

Configuration Register.

4. Master attends to conditions that caused the ALERT to be triggered. The fan is started, setpoint limits are

adjusted, etc.

5. Master resets the ALERT Mask bit in the Configuration Register.

Product Folder Links: LM96163