S8880A Datasheet, PDF (7/30 Pages) Seiko Instruments Inc – ENERGY HARVESTING POWERED BY ULTRA-LOW POWER AND ULTRA-LOW VOLTAGE OPERATION BOOST CHARGE PUMP FOR STEP-UP DC-DC CONVERTER STARTUP

ENERGY HARVESTING POWERED BY ULTRA-LOW POWER AND ULTRA-LOW VOLTAGE OPERATION BOOST CHARGE PUMP FOR STEP-UP DC-DC CONVERTER STARTUP
Rev.1.0_01
S-8880A 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 power-off voltage (V_OFF), the power-off status is entered. When this happens, the internal
oscillation circuit stops its operation, so that the charge pump circuit operation stops, and greatly reduces the current
consumption. Figure 4 shows the configuration of the VM pin.
VM pin
+
−
VM Pin
V_VM < V_OFF
V_VM ≥ V_OFF
Table 8
Internal Circuit
Operate
Stop
V_REF
Figure 4 VM Pin Configuration
Set V_VM during power-off as follows.
3.0 V ≥ V_VM ≥ V_IN + 1.0 V
3.0 V ≥ V_VM ≥ V_OUT
When V_VM < V_IN + 1.0 V occurs, the current consumption during power-off increases.
When V_VM < V_OUT occurs, the discharge control switch leakage current increases.
Caution 1. When not using the VM pin in actual use, be sure to connect it to the VSS pin. If the VM pin is
left open, it may cause malfunctions.
2. 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 status is
released. This operation restarts if V_CPOUT decreases to V_CPOUT2 or lower by discharge of the
startup capacitor (C_CPOUT).
3. Do not connect a high resistance to the VM pin. Note that the VM pin input current (I_VM) max.
may not flow if a high resistance is connected.
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