X40410 Datasheet, PDF(4/24 Page) Intersil Corporation – Dual Voltage Monitor with Intergrated CPU Supervisor

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X40410 Datasheet, PDF (4/24 Pages) Intersil Corporation – Dual Voltage Monitor with Intergrated CPU Supervisor

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X40410, X40411, X40414, X40415

Figure 2. VTRIPX Set/Reset Conditions

VTRIPX

(X = 1, 2)

VCC/V2MON

WDO

SCL

SDA

A0h

WATCHDOG TIMER

The Watchdog Timer circuit monitors the microprocessor

activity by monitoring the SDA and SCL pins. The micro-

processor must toggle the SDA pin HIGH to LOW period-

ically, while SCL also toggles from HIGH to LOW (this is

a start bit) followed by a stop condition prior to the expira-

tion of the watchdog time out period to prevent a WDO

signal going active. The state of two nonvolatile control

bits in the Status Register determines the watchdog timer

period. The microprocessor can change these watchdog

bits by writing to the X40410/11/14/15 control register

(also refer to page 19).

Figure 3. Watchdog Restart

.6Âµs

1.3Âµs

SCL

SDA

Timer Start

V1 AND V2 THRESHOLD PROGRAM PROCEDURE

(OPTIONAL)

The X40410/11/14/15is shipped with standard V1 and

V2 threshold (VTRIP1, VTRIP2) voltages. These values

will not change over normal operating and storage

conditions. However, in applications where the stan-

dard thresholds are not exactly right, or if higher preci-

sion is needed in the threshold value, the

X40410/11/14/15 trip points may be adjusted. The pro-

cedure is described below, and uses the application of

a high voltage control signal.

00h

tWC

Setting a VTRIPx Voltage (x = 1, 2)

There are two procedures used to set the threshold

voltages (VTRIPx), depending if the threshold voltage

to be stored is higher or lower than the present value.

For example, if the present VTRIPx is 2.9 V and the

new VTRIPx is 3.2 V, the new voltage can be stored

directly into the VTRIPx cell. If however, the new setting

is to be lower than the present setting, then it is neces-

sary to âresetâ the VTRIPx voltage before setting the

new value.

Setting a Higher VTRIPx Voltage (x = 1, 2)

To set a VTRIPx threshold to a new voltage which is

higher than the present threshold, the user must apply

the desired VTRIPx threshold voltage to the corre-

sponding input pin Vcc(V1MON), or V2MON. The

Vcc(V1MON) and V2MON must be tied together dur-

ing this sequence. Then, a programming voltage (Vp)

must be applied to the WDO pin before a START con-

dition is set up on SDA. Next, issue on the SDA pin the

Slave Address A0h, followed by the Byte Address 01h

for VTRIP1 and 09h for VTRIP2, and a 00h Data Byte in

order to program VTRIPx. The STOP bit following a

valid write operation initiates the programming

sequence. Pin WDO must then be brought LOW to

complete the operation.

Note: This operation does not corrupt the memory

array.

Setting a Lower VTRIPx Voltage (x = 1, 2)

In order to set VTRIPx to a lower voltage than the

present value, then VTRIPx must first be âresetâ accord-

ing to the procedure described below. Once VTRIPx

has been âresetâ, then VTRIPx can be set to the desired

voltage using the procedure described in âSetting a

Higher VTRIPx Voltageâ.

FN8116.0

March 28, 2005

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