Datasheet MAX1614 (Analog Devices) - 7
| Hersteller | Analog Devices |
| Beschreibung | High-Side, n-Channel MOSFET Switch Driver |
| Seiten / Seite | 9 / 7 — Simple Low-Battery Disconnect/Fresh. Battery Reconnect Circuit. MAX1614. … |
| Dateiformat / Größe | PDF / 1.0 Mb |
| Dokumentensprache | Englisch |
Simple Low-Battery Disconnect/Fresh. Battery Reconnect Circuit. MAX1614. Using LBO to Generate Early Power-Fail. Interrupt
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MAX1614 High-Side, n-Channel MOSFET Switch Driver
Simple Low-Battery Disconnect/Fresh Battery Reconnect Circuit
A simple undervoltage disconnect circuit is often desirable
MAX1614
to prevent damage to secondary batteries due to repeated deep discharge or cell reversal. The Typical Operating SHUTDOWN Circuit turns off the MAX1614, disconnecting the battery OFF (CMOS OR TTL LOGIC) from the load when the battery voltage falls below the mini- mum battery voltage required, (VLOW BATT). VLOW BATT = (R1 + R2)/R2 x VTH where VTH is the LBI input threshold (1.20V typ). When fresh cells are installed or the batteries GND ON are recharged, a μC or pushbutton reconnects the load.
Using LBO to Generate Early Power-Fail Interrupt
Many applications require an early warning indicating Figure 2. Single-Line Shutdown Control that power is failing so that the microprocessor (μP) can take care of any “housekeeping” functions (storing current settings in memory, etc.) before the power fails. Connect LBI through a resistor divider across the battery, and N N LOAD connect LBO to the μP nonmaskable interrupt (NMI). Set the threshold so that LBO goes low when the battery decays to a point where regulation begins to degrade (Figure 4). VLOW BATT = (R1 + R2)/R2 x VTH, where VTH is the LBI input threshold (1.20V typ). Once housekeeping GATE SRC is complete, the μP can turn off the load by pulling OFF low. ON
MAX1614
BATT OFF TO µC R1 N N LOAD LBO LBI R2 GND GATE SRC ON
MAX1614
TO µC Figure 3. Single-Pushbutton On/Off Control BATT PORT PINS OFF
On/Off Control with a Single Pushbutton
R1
Switch
TO µC LBO NONMASKABLE The MAX1614’s separate on and off inputs allow maximum LBI INTERRUPT flexibility in controlling the external MOSFETs. Connect R2 a pushbutton switch to the ON pin and microcontroller GND (μC) I/O for single-button control. Connect the OFF pin to another μC I/O pin. On the first button depression, the MAX1614 turns on automatically; the signal is also detect- ed by the μC. When the button is depressed a second time, Figure 4. Using LBO to Generate Early Power-Fail Interrupt the μC wraps around and turns off the MAX1614 by pulling low on the OFF pin (Figure 3). www.maximintegrated.com Maxim Integrated │ 7
Simple Low-Battery Disconnect/Fresh Battery Reconnect Circuit
A simple undervoltage disconnect circuit is often desirable
MAX1614
to prevent damage to secondary batteries due to repeated deep discharge or cell reversal. The Typical Operating SHUTDOWN Circuit turns off the MAX1614, disconnecting the battery OFF (CMOS OR TTL LOGIC) from the load when the battery voltage falls below the mini- mum battery voltage required, (VLOW BATT). VLOW BATT = (R1 + R2)/R2 x VTH where VTH is the LBI input threshold (1.20V typ). When fresh cells are installed or the batteries GND ON are recharged, a μC or pushbutton reconnects the load.
Using LBO to Generate Early Power-Fail Interrupt
Many applications require an early warning indicating Figure 2. Single-Line Shutdown Control that power is failing so that the microprocessor (μP) can take care of any “housekeeping” functions (storing current settings in memory, etc.) before the power fails. Connect LBI through a resistor divider across the battery, and N N LOAD connect LBO to the μP nonmaskable interrupt (NMI). Set the threshold so that LBO goes low when the battery decays to a point where regulation begins to degrade (Figure 4). VLOW BATT = (R1 + R2)/R2 x VTH, where VTH is the LBI input threshold (1.20V typ). Once housekeeping GATE SRC is complete, the μP can turn off the load by pulling OFF low. ON
MAX1614
BATT OFF TO µC R1 N N LOAD LBO LBI R2 GND GATE SRC ON
MAX1614
TO µC Figure 3. Single-Pushbutton On/Off Control BATT PORT PINS OFF
On/Off Control with a Single Pushbutton
R1
Switch
TO µC LBO NONMASKABLE The MAX1614’s separate on and off inputs allow maximum LBI INTERRUPT flexibility in controlling the external MOSFETs. Connect R2 a pushbutton switch to the ON pin and microcontroller GND (μC) I/O for single-button control. Connect the OFF pin to another μC I/O pin. On the first button depression, the MAX1614 turns on automatically; the signal is also detect- ed by the μC. When the button is depressed a second time, Figure 4. Using LBO to Generate Early Power-Fail Interrupt the μC wraps around and turns off the MAX1614 by pulling low on the OFF pin (Figure 3). www.maximintegrated.com Maxim Integrated │ 7