MIC2507 Datasheet, PDF (7/8 Pages) Micrel Semiconductor – Quad Integrated High-Side Switch Not Recommended for New Designs

MIC2507
Functional Description
The MIC2507 is a noninverting device. A TTL high applied to
a CTL (control) input turns on the respective output transistor.
A TTL low turns off the output transistor. Overcurrent and
overtemperature fault conditions inhibit MOSFET turn on.
Supply Inputs
IN1 (supply input #1) is the supply side of switch #1 but also
powers the common oscillator, thermal shutdown, and flag.
Power must be applied to IN1 to use switch #2, #3, or #4. IN1
powers the charge pump for switch #1.
IN2, IN3, and IN4 are the supplies for switches #2, #3, and #4,
respectively. Each supply input powers its respective charge
pump and control input circuitry.
Control Input
Applying a TTL high signal to any CTL input activates the
oscillator and the CTL input’s respective charge pump and
gate control circuit. If there are no fault conditions, the output
MOSFET turns ON.
Oscillator/Charge Pump
The oscillator produces a 100kHz square wave output which
drives each charge pump. The oscillator is disabled when all
CTL inputs are low or die temperature is greater than 135°C.
Each charge pump is a voltage quintupler (5×). Its output
voltage is clamped to prevent the output switch gate oxide
damage. The charge pump capacitors are self contained.
Gate Control
Each gate control circuit charges the output MOSFET’s gate
from its charge pump or discharges the MOSFET gate to
ground as determined by the control input and thermal
shutdown.
Micrel
Thermal Shutdown
Thermal shutdown shuts off all output MOSFETs and signals
the fault flag if the die temperature exceeds approximately
135°C. 10°C of hysteresis prevents the switch from turning
on until the die temperature drops to approximately 125°C.
Thermal shutdown is indicated by the fault flag only when
CTL is high (MOSFET on).
Overcurrent Limit
The overcurrent limit level is preset internally. The preset
level prevents damage to the output MOSFET but allows a
minimum current of 1A through the output MOSFET. Output
current is monitored across an internal shunt resistor.
Overcurrent detection functions only when CTL is logic high
(output is on).
Open-Load Detection
Open-load detection indicates the absence of an output load
by signaling the fault flag. Open-load detection is optional
and is enabled by connecting a high-value pull-up resistor
between IN and OUT. If there is no load, the circuit detects
a high OUT voltage and signals the fault flag. Under normal
conditions, the low resistance of a typical load pulls OUT low.
Open-load detection functions only when CTL is low (output
is off).
Fault Flag
FLG (fault flag) is an N-channel open-drain MOSFET output.
The fault-flag MOSFET is active (low) for one or more of the
following conditions on any one or more outputs: open load,
current limit, or thermal shutdown.
August 1999
7
MIC2507