S-882Z Datasheet, PDF (9/24 Pages) Seiko Instruments Inc – ULTRA-LOW VOLTAGE OPERATION CHARGE PUMP IC FOR STEP-UP DC-DC CONVERTER STARTUP

ULTRA-LOW VOLTAGE OPERATION CHARGE PUMP IC FOR STEP-UP DC-DC CONVERTER STARTUP
Rev.1.2_00
S-882Z Series
2. Step-up DC-DC Converter Output Voltage Monitor Pin (VM Pin)
When the output voltage of the step-up DC-DC converter to be monitored rises and the VM pin voltage (V_VM)
reaches or exceeds the shutdown voltage (V_OFF), the shutdown state is entered. When this happens, the internal
oscillation circuit stops its operation, so that the charge pump circuit operation stops, and greatly reduces the
power consumption. Figure 13 shows the configuration of the VM pin.
VM pin
+
−
VM Pin
V_VM < V_OFF
V_VM ≥ V_OFF
Table 5
Internal Circuit
Operating
Shutdown
VREF
Figure 13 VM Pin Configuration
Set V_VM during shutdown as follows.
V_VM ≥ V_IN + 1.0 V
V_VM ≥ V_OUT
When V_VM < V_IN + 1.0 V occurs, the shutdown current consumption increases.
When V_VM < V_OUT occurs, the discharge control switch leak current increases.
Caution1.
2.
When not using the VM pin, be sure to connect it to the VSS pin. If the VM pin is left open, it
may cause malfunctions.
Note that the operation to restart a step-up DC-DC converter does not start when CPOUT pin
voltage (V_CPOUT) exceeds the discharge stop voltage (V_CPOUT2) even if the power-off state is
released. This operation restarts if V_CPOUT is lowered than V_CPOUT2 by discharge of a start-up
capacitor (C_CPOUT).
Seiko Instruments Inc.
9