Microchip MIC23030-4YMT Bedienungsanleitung


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MIC23030 Evaluation Board
8MHz PWM 400mA Buck Regulator
with HyperLight Load™
HyperLight Load is a trademark of Micrel, Inc. MLF is a registered trademark of Amkor Technology.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
August 2008 M9999-072208-A
General Description
The MIC23030 is a 400mA 8MHz switching regulator
featuring HyperLight Load™ mode. The MIC23030 is
highly efficient throughout the entire output current range,
drawing just 21µA of quiescent current in operation. The
tiny 1.6 x 1.6mm MLF® package, in combination with the
8MHz switching frequency, enables a compact sub-1mm
height solution with only three external components. The
MIC23030 provides accurate output voltage regulation
under the most demanding conditions and responds
extremely quickly to a load transient with exceptionally
small output voltage ripple.
Factoring in the output current, the internal circuitry of the
MIC23030 automatically selects between two modes of
operation for optimum efficiency. Under light load
conditions, the MIC23030 goes into HyperLight Load
mode. HyperLight Load uses a Pulse-Frequency
Modulation (PFM) control scheme that controls the off time
at light load. This proprietary architecture reduces the
amount of switching needed at light loads, thereby
increasing operating efficiency. The MIC23030 attains up
to 83% efficiency at 1mA output load. As the load current
increases beyond approximately 100mA, the device
operates using the Pulse-Width Modulation (PWM) method
for up to 91% efficiency at higher loads. The two modes of
operation ensure the highest efficiency across the entire
load range.
The MIC23030 operates from an input voltage range of
2.7V to 5.5V and features internal power MOSFETs that
deliver up to 400mA of output current. This step-down
regulator provides an output voltage accuracy of +/-2.5%
across the junction temperature range of -40ºC to +125ºC.
The MIC23030 is available in fixed or adjustable versions
supporting an output voltage as low as 0.7V.
Requirements
The MIC23030 evaluation board requires an input power
source that is able to deliver greater than 500mA at 2.7V
to the MIC23030. The output load can either be an active
(electronic) or passive (resistive) load.
Getting Started
1. Connect an external supply to the V IN (J1)
terminal. Apply the desired input voltage to VIN
(J1) and ground (J2) terminals of the evaluation
board, paying careful attention to polarity and
supply voltage (2.7V VIN 5.5V). An ammeter
may be placed between the input supply and the
VIN (J1) terminal. Be sure to monitor the supply
voltage at the VIN (J1) terminal, since the ammeter
and/or power lead resistance can reduce the
voltage supplied to the device.
2. Connect a load to the VOUT (J3) and ground
terminal (J4). The load can be either passive
(resistive) or active (electronic load). An ammeter
may be placed between the load and the output
terminal. Ensure the output voltage is monitored at
the VOUT (J3) terminal.
3. Enable the MIC23030. The MIC23030 evaluation
board has a pull-up resistor to VIN. To disable the
device, apply a voltage below 0.5V to the EN (J5)
terminal or place a jumper on JP1 to ground the
enable. In the absence of the pull-up resistor, the
device is enabled by applying a voltage greater
than 1.2V to the EN (J5) terminal. The enable pin
must be either pulled high or low for proper
operation. Removing the pull-up resistor and
leaving the pin floating will cause the regulator to
operate in an indeterminable state.
Output Voltage
The MIC23030 evaluation board is available with the
following output voltage options listed below:
Ordering Information
Part Number Description
MIC23030-AYMT EV Adjustable Output Evaluation Board
MIC23030-CYMT EV 1.0V Fixed Output Evaluation Board
MIC23030-4YMT EV 1.2V Fixed Output Evaluation Board
MIC23030-FYMT EV 1.5V Fixed Output Evaluation Board
MIC23030-GYMT EV 1.8V Fixed Output Evaluation Board
Note: Other voltage options available on request
Micrel, Inc. MIC23030 Evaluation Board
August 2008 2 M9999-072208-A
Output Voltage (Adjustable Option Only)
The output voltage of the MIC23030-AYMT regulator is
determined by feedback resistors R1 and R2 whose
values are calculated as follows:
+×= 1
R2
R1
0.62VVOUT
The output on the evaluation board is by default set to
1.8V (R1=383k, R2=200k), but can easily be modified
by removing R1 and replacing it with the value that yields
the desired output voltage.
R21
0.62V
V
R1 OUT ×
=
For optimum transient response performance, R2 should
be in the range of 180kΩ Ω to 220k .
HyperLight Load™ Mode
MIC23030 uses a patented minimum on and off time
control loop at light loads. When the output voltage falls
below the lower regulation threshold, the error comparator
begins a switching cycle that turns the PMOS on and
keeps it on for the duration of the minimum-on-time. This
increases the output voltage. Once the output voltage rises
to the higher regulation threshold, the error comparator
turns the PMOS off for a minimum off time until the output
drops down to the lower threshold. The NMOS acts as an
ideal rectifier that conducts when the PMOS is off. Using a
NMOS switch instead of a diode, reduces power
dissipation as the current is sourced from ground. In
discontinuous mode, the MIC23030 works in pulse
frequency modulation (PFM) to regulate the output. As the
output current increases, the off-time decreases, more
energy is delivered to the output. This switching scheme
improves the efficiency of MIC23030 during light load
currents by activating the power FETs only as needed. As
the load current increases, the MIC23030 goes into
continuous conduction mode (CCM) and switches at a
frequency centered at 8MHz. The equation to calculate the
load where the MIC23030 goes into continuous conduction
mode is approximated by the following formula:
×
×
>fL
DVV
IOUTIN
LOAD 2
)(
As shown in the previous equation, the load at which
MIC23030 transitions from HyperLight Load™ mode to
PWM mode is a function of the input voltage (V IN), output
voltage (VOUT), duty cycle (D), inductance (L) and
frequency (f). This is illustrated in the graph below.
Suitable inductors for the MIC23030 range from 0.47µH to
2.2µH. The device may be tailored to enter HyperLight
Load™ mode or PWM mode at a specific load current by
selecting the appropriate inductor. For example, if a 2.2µH
inductor is selected in a 3.6VIN to 1.8VOUT application, the
MIC23030 will transition into PWM mode at a load of
approximately 30mA. If under the same condition a 0.47µH
inductor is chosen, the MIC23030 will transition into PWM
mode at approximately 120mA.
SW Frequency vs. Inductance
Micrel, Inc. MIC23030 Evaluation Board
August 2008 3 M9999-072208-A
MIC23030 Typical Application Circuit (Fixed)
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1, C2 C1608X5R0J475K TDK(1) 4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2
R1 CRCW06031003FT1 Vishay(2) 100k, 1%, Size 0603 1
LQM21PNR47M00 Murata(3) 0.47µH, 0.9A, 90m, L2mm x W1.25mm x H0.5mm
LQH32CNR47M33 Murata(3) 0.47µH, 1.1A, 42m, L3.2mm x W2.5mm x H2.0mm
LQM31PNR47M00 Murata(3) 0.47µH, 1.4A, 80m, L3.2mm x W1.6mm x H0.85mm
GLF251812T1R0M TDK(1) 1µH, 0.8A, 100m, L2.5mm x W1.8mm x H1.35mm
MIPF2520D1R5 FDK(4) 1.5µH, 1.5A, 70m, L2.5mm x W2mm x H1.0mm
L1
EPL2010-471 Coilcraft(5) 0.47µH, 1.6A, 40m, L2.0mm x W1.8mm x H1.0mm
1
U1 MIC23030-xYMT Micrel, Inc.(6) 8MHz 400mA Buck Regulator with HyperLight Load™ Mode 1
Notes:
1. TDK: www.tdk.com
2. Vishay: www.vishay.com
3. Murata: www.murata.com
4. FDK: www.fdk.co.jp
5. Coilcraft: www.coilcraft.com
6. Micrel, Inc.: www.micrel.com


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Marke: Microchip
Kategorie: Nicht kategorisiert
Modell: MIC23030-4YMT

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