Woodstock Low Power

[PANAMATIK]

Hello Max

According to the datasheet of the GPS voltage booster only input voltages above 1.2V would enable the booster. Even when battery voltage is as low as 2.0 volts, the /SHDN output should deliver >1.2V. I still cannot see why you have this problem. Perhaps the booster is defective, or the /SHDN wire has bad contact. I would offer to examine your calculator and test with low voltages if you sent it to me.

Bernhard

Excerpt from datasheet:

Quote:The SHDN can be driven low (typically under 0.4 V) to power down the regulator and turn off power to the load (unlike most boost regulators, the input power does not pass through to the output when the board is disabled). This pin is internally pulled up to VIN through an 100 kΩ resistor, so it can be left disconnected or connected directly to VIN if you do not need to use the disable feature. The disable threshold is a function of the input voltage as follows:

For VIN < 0.8 V, SHDN voltage must be below 0.1×VIN to disable the regulator and above 0.9×VIN to enable it.
For 0.8 V ≤ VIN ≤ 1.5 V, SHDN voltage must be below 0.2×VIN to disable the regulator and above 0.8×VIN to enable it.
For VIN > 1.5 V, SHDN voltage must be below 0.4 V to disable the regulator and above 1.2 V to enable it.

The input voltage, VIN, must be at least 0.5 V for the regulator to turn on. However, once the regulator is on, the input voltage can drop as low as 0.3 V and the 3.3 V output voltage will be maintained on VOUT.