MIC4421ZM Micrel Inc, MIC4421ZM Datasheet - Page 7

• Manufacturer Part Number: MIC4421ZM
• Description: IC DRIVER MOSFET 9A LS 8-SOIC
• Manufacturer: Micrel Inc

Specifications of MIC4421ZM

• Lead Free Status: Lead free
• Configuration: Low-Side
• Input Type: Inverting
• Delay Time: 15ns
• Current - Peak: 9A
• Number Of Configurations: 1
• Number Of Outputs: 1
• Voltage - Supply: 4.5 V ~ 18 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• High Side Voltage - Max (bootstrap): -
• Other names: 576-1792-5; MIC4421ZM

MIC4421/4422
August 2005
Applications Information
Supply Bypassing
Charging and discharging large capacitive loads quickly
requires large currents. For example, charging a 10,000pF
load to 18V in 50ns requires 3.6A.
The MIC4421/4422 has double bonding on the supply pins,
the ground pins and output pins. This reduces parasitic
lead inductance. Low inductance enables large currents to
be switched rapidly. It also reduces internal ringing that can
cause voltage breakdown when the driver is operated at or
near the maximum rated voltage.
Internal ringing can also cause output oscillation due to
feedback. This feedback is added to the input signal since it
is referenced to the same ground.
CONTROL 180° TO 360°
CONDUCTION ANGLE
CONDUCTION ANGLE
CONT ROL 0° TO 180°
Ø 1 DRIV E S IGNA L
0.1µF
50V
0.1µF
WIMA
MKS2
2
+15
MIC4421
1
4
Figure 3. Direct Motor Drive
8
5
D R I V E
L OGIC
+
(x2) 1N4448
6, 7
1µF
50V
MKS2
UNIT E D CHE MCON S X E
MIC4452
MIC4451
5.6 kΩ
560 Ω
V S
V S
560µF 50V
1µF
1µF
DRIVER USING MIC4420/4429
PHASE 1 of 3 PHASE MOTOR
Ø 1
Figure 4. Self Contained Voltage Doubler
+
100µF 50V
Ø 2
M
BYV 10 (x 2)
V S
V S
Ø 3
+
7
To guarantee low supply impedance over a wide frequency
range, a parallel capacitor combination is recommended for
supply bypassing. Low inductance ceramic disk capacitors
with short lead lengths (< 0.5 inch) should be used. A 1µF low
ESR film capacitor in parallel with two 0.1µF low ESR ceramic
capacitors, (such as AVX RAM Guard
bypassing. Connect one ceramic capacitor directly between
pins 1 and 4. Connect the second ceramic capacitor directly
between pins 8 and 5.
Grounding
The high current capability of the MIC4421/4422 demands
careful PC board layout for best performance. Since the
MIC4421 is an inverting driver, any ground lead impedance
will appear as negative feedback which can degrade switching
speed. Feedback is especially noticeable with slow-rise time
inputs. The MIC4421 input structure includes about 200mV
of hysteresis to ensure clean transitions and freedom from
oscillation, but attention to layout is still recommended.
Figure 5 shows the feedback effect in detail. As the MIC4421
input begins to go positive, the output goes negative and
several amperes of current flow in the ground lead. As little
as 0.05Ω of PC trace resistance can produce hundreds of
millivolts at the MIC4421 ground pins. If the driving logic is
referenced to power ground, the effective logic input level is
reduced and oscillation may result.
To insure optimum performance, separate ground traces
should be provided for the logic and power connections. Con-
necting the logic ground directly to the MIC4421 GND pins
will ensure full logic drive to the input and ensure fast output
switching. Both of the MIC4421 GND pins should, however,
still be connected to power ground.
30
29
28
27
26
25
0
OUTPUT VOLTAGE vs LOAD CURRENT
50
100 150 200 250 300 350
mA
12 Ω LIN E
®
), provides adequate
M9999-081005
Micrel, Inc.