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Teilenummer | MIC2076A |
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Beschreibung | Dual-Channel Power Distribution Switch | |
Hersteller | Micrel Semiconductor | |
Logo | ||
Gesamt 16 Seiten MIC2026/2076
Micrel
MIC2026/2026A/2076/2076A
Dual-Channel Power Distribution Switch
General Description
The MIC2026 and MIC2076 are high-side MOSFET switches
optimized for general-purpose power distribution requiring
circuit protection.
The MIC2026/76 are internally current limited and have
thermal shutdown that protects the device and load.
The MIC2076 offers “smart” thermal shutdown that reduces
current consumption in fault modes. When a thermal shut-
down fault occurs, the output is latched off until the faulty load
is removed. Removing the load or toggling the enable input
will reset the device output.
Both devices employ soft-start circuitry that minimizes inrush
current in applications where highly capacitive loads are
employed.
A fault status output flag is asserted during overcurrent and
thermal shutdown conditions. Transient faults are internally
filtered.
The MIC2026/76 are available in 8-pin DIP or 8-lead SOP.
Features
• 140mΩ maximum on-resistance per channel
• 2.7V to 5.5V operating range
• 500mA minimum continuous current per channel
• Shortcircuit protection with thermal shutdown
• Thermally isolated channels
• Fault status flag with 3ms filter eliminates false asser-
tions (MIC2026A/2076A with 10ms filter)
• Undervoltwww.sony.com/clieage lockout
• Reverse current flow blocking (no “body diode”)
• Circuit breaker mode (MIC2076)
• Logic-compatible inputs
• Soft-start circuit
• Low quiescent current
• Pin compatible with MIC2526
Applications
• USB peripherals
• General purpose power switching
• ACPI power distribution
• Notebook PCs
• PDAs
• PC card hot swap
Typical Application
VCONT.
10k
10k
Logic Controller
VIN ON/OFF
OVERCURRENT
OVERCURRENT
ON/OFF
VCC
2.7V to 5.5V
MIC2026-2
ENA
FLGA
FLGB
ENB
OUTA
IN
GND
OUTB
Load
0.1µF
Load
UL Recognized Component
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
February 1, 2001
1
MIC2026/2076
MIC2026/2076
Enable Threshold
vs. Temperature
2.5
2.0 VEN RISING
1.5
VEN FALLING
1.0
0.5
VIN = 5V
-040 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Enable Threshold
vs. Input Voltage
2.5
2.0 VEN RISING
1.5
1.0 VEN FALLING
0.5
02.5
TA = 25°C
3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
Flag Delay
vs. Temperature
5
VIN = 3.3V
4
VIN = 5V
3
2
1
0-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Flag Delay
vs. Input Voltage
5
+85°C
4
3 +25°C
2 -40°C
1
02.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
UVLO Threshold
vs. Temperature
3.0
2.5 VIN RISING
2.0
VIN FALLING
1.5
1.0
0.5
-040 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Micrel
Supply Off Current
vs. Temperature
0.16
0.14
0.12
5V
0.1
0.08
0.06
0.04
3.3V
0.02
-040 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Supply Off Current
vs. Input Voltage
0.18
0.16
0.14
+85°C
0.12
0.10
0.08
0.06 +25°C
0.04 -40°C
0.02
02.5 3.0 3.5 4.0 4.5 5.0 5.5
VOLTAGE (V)
MIC2026/2076
6 February 1, 2001
6 Page MIC2026/2076
Applications Information
Supply Filtering
A 0.1µF to 1µF bypass capacitor positioned close to VIN and
GND of the device is strongly recommended to control supply
transients. Without a bypass capacitor, an output short may
cause sufficient ringing on the input (from supply lead induc-
tance) to damage internal control circuitry.
Printed Circuit Board Hot-Plug
The MIC2026/76 are ideal inrush current-limiters for hot plug
applications. Due to the integrated charge pump, the
MIC2026/76 presents a high impedance when off and slowly
becomes a low impedance as it turns on. This “soft-start”
feature effectively isolates power supplies from highly ca-
pacitive loads by reducing inrush current. Figure 3 shows how
the MIC2076 may be used in a card hot-plug application.
In cases of extremely large capacitive loads (>400µF), the
length of the transient due to inrush current may exceed the
delay provided by the integrated filter. Since this inrush
current exceeds the current-limit delay specification, FLG will
be asserted during this time. To prevent the logic controller
from responding to FLG being asserted, an external RC filter,
as shown in Figure 4, can be used to filter out transient FLG
assertion. The value of the RC time constant should be
selected to match the length of the transient, less tD(min) of the
MIC2026/76.
Micrel
Universal Serial Bus (USB) Power Distribution
The MIC2026/76 is ideally suited for USB (Universal Serial
Bus) power distribution applications. The USB specification
defines power distribution for USB host systems such as PCs
and USB hubs. Hubs can either be self-powered or bus-
powered (that is, powered from the bus). Figure 5 shows a
typical USB Host application that may be suited for mobile PC
applications employing USB. The requirement for USB host
systems is that the port must supply a minimum of 500mA at
an output voltage of 5V ±5%. In addition, the output power
delivered must be limited to below 25VA. Upon an overcurrent
condition, the host must also be notified. To support hot-plug
events, the hub must have a minimum of 120µF of bulk
capacitance, preferably low ESR electrolytic or tantulum.
Please refer to Application Note 17 for more details on
designing compliant USB hub and host systems.
For bus-powered hubs, USB requires that each downstream
port be switched on or off under control by the host. Up to four
downstream ports each capable of supplying 100mA at 4.4V
minimum are allowed. In addition, to reduce voltage droop on
the upstream VBUS, soft-start is necessary. Although the hub
can consume up to 500mA from the upstream bus, the hub
must consume only 100mA max at start-up, until it enumer-
ates with the host prior to requesting more power. The same
requirements apply for bus-powered peripherals that have no
downstream ports. Figure 6 shows a bus-powered hub.
VBUS
to "Hot"
Receptacle
GND
Cable
MIC2026-2BM
1 ENA OUTA 8
4.7 2 FLGA
IN 7
µF 3 FLGB GND 6
4 ENB OUTB 5
USB Peripheral
USB
Controller
USB
Function
CBULK
USB
Function
CBULK
Figure 3. Hot-Plug Application
Logic Controller
OVERCURRENT
V+
10k
R
C
MIC2026
1 EN
OUTA 8
2 FLGA
IN 7
3 FLGB GND 6
4 ENB OUTB 5
Figure 4. Transient Filter
MIC2026/2076
12
February 1, 2001
12 Page | ||
Seiten | Gesamt 16 Seiten | |
PDF Download | [ MIC2076A Schematic.PDF ] |
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