MIC4103 Datasheet, PDF (9/17 Pages) Micrel Semiconductor – 100V Half Bridge MOSFET Drivers 3/2A Sinking/Sourcing Current

Micrel
Functional Characteristics
MIC4103/4104
Figure 1. MIC4103/4 Functional Block Diagram
Functional Description
The MIC4103 is a high voltage, non-inverting, dual
MOSFET driver that is designed to independently drive
both high-side and low-side N-Channel MOSFETs. The
block diagram of the MIC4103 is shown in Figure 1.
Both drivers contain an input buffer with hysteresis, a
UVLO circuit and an output buffer. The high-side output
buffer includes a high speed level-shifting circuit that is
referenced to the HS pin. An internal diode is used as part
of a bootstrap circuit to provide the drive voltage for the
high-side output.
Startup and UVLO
The UVLO circuit forces the driver output low until the
supply voltage exceeds the UVLO threshold. The low-side
UVLO circuit, monitors the voltage between the VDD and
VSS pins. The high-side UVLO circuit monitors the voltage
between the HB and HS pins. Hysteresis in the UVLO
circuit prevents noise and finite circuit impedance from
causing chatter during turn-on.
where the input signal is noisy or where the input signal
swings the full range of voltage (from V_DD to GND). There
is typically 400mV of hysteresis on the input pins
throughout the VDD range. The hysteresis improves noise
immunity and prevents input signals with slow rise times
from falsely triggering the output. The threshold voltage of
the MIC4103 varies proportionally with the VDD supply
voltage.
The amplitude of the input signal affects the VDD supply
current. Vin voltages that are a diode drop less than the
VDD supply voltage will cause an increase in the VDD pin
current. The graph in Figure 2 shows the typical
dependence between I_VDD and Vin for Vdd=12V.
Input Stage
The MIC4103 and MIC4104 have different input stages,
which lets these parts cover a wide range of driver
applications. Both the HI and LI pins are referenced to the
VSS pin.
The MIC4103 has a high impedance, CMOS compatible
input threshold and is recommended for applications
October 2007
9
M9999-100107-B