Data Sheet

Rev 0 9
1 1 1.256V 1.256×(1＋10%)
Resistor divider network design example
Suppose you want to monitor a single lithium battery voltage, battery voltage drops, four in ascending
order of the voltage detection points were Vth1 = 3.19V, Vth2 = 3.47V, Vth3 = 3.69V and Vth4 = 3.99V.
Set R1 + R2 + R3 + R4 + R5 = 720KΩ, so the battery voltage is 3.6V, the resistor divider network
consumes battery current 5uA, general portable products can be tolerated.
R5＝(1.22／3.99)×720＝220KΩ
R4＝(1.22／3.69)×720－220＝18KΩ
R3＝(1.22／3.47)×720－220－18＝15KΩ
R2＝(1.22／3.19)×720－220－18－15＝22KΩ
R1＝720－220－18－15－22＝445KΩ
Monitoring the voltage greater than 6V
If the monitored voltage greater than 6V, you can be connected to monitor voltage resistor divider network
of high-end, but pay attention to any case through the resistor divider network after receiving the CN1185
partial pressure comparator input voltage is not higher than 6V. CN1185 need 2.7V to 6V power supply, the
power system can be 2.7V to 6V already have the power, or voltage to be monitored or regulated through
the step-down power.
About the filter capacitor
Generally, CN1185 does not require power supply filter capacitor. However, if the CN1185 work in a
relatively strong noise or electromagnetic interference environment, or be monitored power itself
superimposed clutter, then add a 0.1uF capacitor between VDD and GND can effectively filter out
interference. If the monitored power supply voltage transients are relatively strong, the filter capacitor
value should be larger. From the comparator's negative input to ground plus a 1nF capacitor can effectively
improve the noise immunity of CN1185.
CN1185 to achieve three-color LED indicates
Some applications require the use of CN1185 to achieve three-color LED indicates when the battery
voltage is higher than a certain threshold, the green light, the battery has enough energy. When the battery
voltage is between a higher threshold and lower threshold, the yellow light (actually a red light and green
light); when the battery voltage is below the lower threshold value, the red indicator light to alert the user
needs charging the battery. Shown in Figure 3.