W83L784R_05 Datasheet, PDF (15/52 Pages) Winbond – Monitoring IC

W83L784R/ W83L784G
6.3.1 Monitor over 4.096V voltage:
The input voltage VIN3 can be expressed as following equation.
VIN 3 = V_{BAT −DC}
×
R₂
R₁ + R₂
The value of R1 and R2 can be selected to 232K Ohms and 99K Ohms, respectively, when the input
voltage V_BAT-DC is 10V. The node voltage of VIN3 can be subject to less than 4.096V for the maximum
input range of the 8-bit ADC. The pin 24 is connected to the power supply VCC with +5V. There are
two functions in this pin with 5V. The first function is to supply internal analog power in the W83L784R
and the second function is that this voltage with 5V is connected to internal serial resistors to monitor
the +5V voltage. The values of two serial resistors are 34K ohms and 50K ohms so that input voltage
to ADC is 2.98V which is less than 4.096V of ADC maximum input voltage. The express equation can
represent as follows.
50KΩ
V_in = VCC × _{50KΩ + 34KΩ} ≅ 2.98V
where VCC is set to 5V
6.3.2 Power good for 3V and 5V
On power up, once VCC (5V) reaches 1V, RESET# will be logic low. As 3V and VCC (5V) rise,
RESET# remains asserted. If 3V and VCC (5V) both exceed the reset threshold, RESET becomes
logic high after a time equal to the reset pulse width (tRST, typically 200ms). (Figure 11) If a power fail
or a brownout happens (i.e. 3V or VCC (5V) drops below the threshold), RESET# output is asserted.
As long as the 3V and VCC (5V) remain below the reset threshold, RESET# output remains asserted.
Therefore, a brownout condition that interrupts a previously initiated reset pulse causes an additional
200ms delay from the time the latest interruption occurred. On power-on, once 3Vor VCC (5V) drops
below the reset threshold, RESET# are guaranteed to be asserted for VCC ≥ 1V.
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Publication Release Date: Jan. 2005
Revision 1.1