Datasheet MAX16126, MAX16127 (Analog Devices) - 8

MAX16126/MAX16127
Load-Dump/Reverse-Voltage Protection Circuits
Pin Description PIN NAME FUNCTION
1 SHDN Shutdown Input. Drive SHDN low to force GATE and FLAG low and turn off the external n-channel MOSFETs. Connect a 100kΩ resistor from SHDN to IN for normal operation. 2 TERM Voltage-Divider Termination Output. TERM is internally connected to IN. TERM is high impedance when SHDN is low, forcing the current to zero in the resistive-divider connected to TERM. 3 N.C. No Connection. Not internally connected. 4 UVSET Undervoltage Threshold Adjustment Input. Connect UVSET to the external resistive voltage-divider network to adjust the desired input undervoltage threshold. Connect the resistive divider to TERM. Overvoltage Threshold Adjustment Input. Connect OVSET to an external resistive voltage-divider network 5 OVSET to adjust the desired overvoltage disable or overvoltage limit threshold. Connect the resistive divider to TERM for overvoltage switch-mode applications or to OUT for overvoltage limiting applications. 6 GND Ground 7 I.C. Internally Connected. Connect to GND. FLAG Output. During startup, FLAG is low as long as VOUT is lower than 90% of VIN and after that 8 FLAG it is high impedance. It asserts low during shutdown mode, an overvoltage, thermal shutdown, or undervoltage fault or when VOUT falls below 90% of VIN. 9 OUT Output Voltage-Sense Input. Connect OUT to the load with a 100Ω series resistor. Bypass the load with a minimum 10µF capacitor to GND. Source Input. Connect SRC to the common source connection of the external MOSFETs. When the 10 SRC MOSFETs are turned off, this connection is clamped to GND. An external zener diode between SRC and GATE protects the gates of the external MOSFETs. Gate-Driver Output. Connect GATE to the gates of the external n-channel MOSFETs. GATE is the 11 GATE charge-pump output during normal operation. GATE is quickly pulled low during a fault condition or when SHDN is pulled low. 12 IN Positive Supply Input Voltage. Connect IN to the positive side of the input voltage. Bypass IN with a 0.1µF ceramic capacitor to GND. — EP Exposed Pad. Can be connected to GND or left unconnected.
Detailed Description
dissipation and voltage drop, and allows the circuit to The MAX16126/MAX16127 transient protection circuits are operate at very low cold-crank voltages (3V minimum). suitable for automotive and industrial applications where The MAX16127 provides a limiter-mode fault manage- high-voltage transients are commonly present on supply ment for overvoltage and thermal shutdown conditions, voltage inputs. The devices monitor the input voltage and whereas the MAX16126 provides switch-mode fault control two external common-source n-channel MOSFETs management for overvoltage and thermal shutdown con- to protect downstream voltage regulators during load-dump ditions. In the limiter mode, the MOSFETs cycle on and events or other automotive pulse conditions. off so the output voltage is limited. In the switch mode, The devices feature an overvoltage and an undervoltage the external MOSFETs are switched off, disconnecting comparator for voltage window detection. A flag output the load from the input. In both cases, FLAG asserts to (FLAG) asserts when a fault event occurs. indicate a fault. Two external back-to-back n-channel MOSFETs provide
Gate Charge Pump
reverse-voltage protection and also prevent reverse cur- The MAX16126/MAX16127 use a charge pump to gener- rent during a fault condition. Compared to a traditional ate the GATE to SRC voltage and enhance the external reverse-battery diode, this approach minimizes power MOSFETs. After the input voltage exceeds the input www.analog.com Analog Devices │ 8