DS2711K Maxim Integrated, DS2711K Datasheet - Page 4

• Manufacturer Part Number: DS2711K
• Description: Power Management IC Development Tools
• Manufacturer: Maxim Integrated
• Series: DS2711, DS2712r

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Charge Rate – Resistors R14 and R15
Resistor R14 sets the charge rate for all AA sockets and the combined resistance of R14+R15 sets the charge rate for all AAA
sockets. The formulas are as follows:
The default values of 0.200 Ohms for R14 and 0.100 Ohms for R15 give set a AA charge rate of .625 amps and a AAA charge
rate of .417 amps for the DS2711 or a AA charge rate of .565 amps and a AAA charge rate of .377 amps for the DS2712.
Charge Time – Resistor R21
Resistor R21 sets the time limit for fast charge and top-off charge as follows:
The default value for R21 is 200K Ohms giving a fast charge duration of 5 hours and a top-off charge of 2.5 hours. The
minimum allowable value for R21 is 20K Ohms giving a fast charge time of 30 minutes and the maximum allowable value is
360K Ohms giving a fast charge time of 9 hours.
Impedance Test – Resistor R20
Resistor R20 sets the voltage level threshold used to prohibit charging of non-NiMH cells using the following formula:
The default value for R20 is 68K Ohms, which sets the Impedance threshold at 200mOhms for AA cells and 300mOhms for
AAA size cells. The maximum allowable value for R20 is 250K Ohms and the minimum value is 20K ohms. R20 cannot be
selected until after the charge rate has been set.
DS2711 AA Charge Rate (A) = 0.125 (V) / R14
DS2711 AAA Charge Rate (A) = 0.125 (V) / (R14 + R15)
DS2712 AA Charge Rate (A) = 0.113 (V) / R14
DS2712 AAA Charge Rate (A) = 0.113 (V) / (R14 + R15)
Fast Charge Time (minutes) = 1.5 * R21 / 1000
Top Off Charge Time (minutes) = ½ Fast Charge Time (minutes)
Impedance threshold (mΩ) = (8000 / R20) * (1 / Charge Rate (A))
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