Microchip MIC45116-1YMP Handleiding


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MIC45116 Evaluation Board
20V/6A/DC- - to DC Power Module
General Description
Micrel’s MIC45116 is a synchronous step down regulator -
module, featuring a unique adaptive ON time control -
architecture. The singular module package cludes in -a DC
to-DC controller, power MOSFETs, bootstrap diode,
bootstrap capacitor, and an inductor; simplifying the design
and layout process for the end user.
This highly integrated solution expedites system design
and improves product time- -to market. The internal
MOSFETs and inductor have been optimized to achieve
high efficiency at a low output voltage. The fully optimized
design can deliver up to a 6A current under a wide input
voltage range of 4.75V to 20V, without an additional
cooling requirement.
The MIC 1 uses Micrel’s HyperLight Load45116- ® . (HLL)
MIC45116-2 uses Micrel’s Hyper Speed Control™
architecture which enables ultra fast load transient -
response s and allow for a reduction of output capacitance.
The MIC45116 offers 1% output accuracy that can be
adjusted from 0.8V input voltage with two up ofto 85% the
external resistors. Note the output capacitor Cb is only
rated to 6.3V.
The basic parameters of th evaluation board include a is
4.75V to 20V input, a 0.8V to 5V at 6A output.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Requirements
The MIC45116 1 and MIC45116 2 evaluation board’s - -
minimum requirement is one power supply with at least 6A
current capability. No external linear regulator is required
to power the internal biasing of the IC because the
MIC45116 has an internal PVDD LDO. In the applications
with VIN < +5.5V, PVDD should be tied to VIN to bypass
the internal linear regulator. The output load can either be
a passive or an active load.
Precautions
The MIC45116 evaluation board does not have reverse
polarity protection. Applying a negative voltage to the VIN
and GND terminals may damage the device. The
maximum VIN of the board is rated at 20V. Exceeding 30V
on the VIN could damage the device. The voltage rating of
the output capacitor is 6.3V. The output capacitor should
be replaced with higher voltage rated one to set the output
voltage above 5V.
Getting Started
1. VIN Supply
Connect a supply to the VIN (TP6) (TP7) and GND
terminals, paying careful attention to the polarity and
the supply range (4.75V < VIN < 20V). Monitor IIN with
a current meter and monitor input voltage at VIN and
GND terminals with a voltmeter. Do not apply power
until Step 4.
2. Connect Load and Monitor Output
Connect a load to the VOUT (TP8) (TP9) and GND
terminals. The load can be either a passive (resistive)
or an active (as in an electronic load) type. A current
meter may be placed between the VOUT terminal and
load to monitor the output current. Ensure the output
voltage is monitored at the VOUT terminal.
3. Enable Input
The EN pin has an on board 100kΩ pull-up resistor
(R4) to VIN, which allows the output to be turned on
when PVDD exceeds its UVLO threshold. An EN
connector (TP3) is provided on the evaluation board
for users to easily access the enable feature. Applying
an external logic signal on the EN pin to pull it low or
using a jumper to short the EN pin to GND will shut off
the output of the MIC45116 evaluation board.
4. Turn Power
Turn on the VIN supply and verify that the output
voltage is regulated to 1.8V.
5. Loop Measurement
Control loop frequency response can be measured by
injecting AC sweep signal and measuring voltage
across test points A and B. R3 should change to a
small resistor value in the range of 10 to 20Ω Ω for the
loop measurement.
Ordering Information
Part Number Description
MIC45116 MIC45116- 1YMP EV -1 Evaluation Board
MIC45116 MIC45116- 2YMP EV -2 Evaluation Board
Hyper LightLoad is a registered trademark of Micrel, Inc.
Hyper Speed Control is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
March 12 , 2015 Revision 1.0
Micrel, Inc.
MIC45116 Evaluation Board
Features
Feedback Resistors
The output voltage on the MIC45116 evaluation board,
which is preset to 1.8V, is determined by the feedback
divider, as illustrated in Equation 1:







+×=
BOTTOM
REFOUT
R
R51
1VV
1 Eq.
where VREF = 0.8V, and RBOTTOM is the lower feedback
resistor.
Leaving the RBOTTOM open by removing all jumpers on the
feedback headers gives a 0.8V output voltage. All other
voltages not listed above can be set by modifying R BOTTOM
value according to Equation 2:
REFOUT
REF
BOTTOM VV
VR51
R−
×
=
2 Eq.
Note that the output voltage should not be set to exceed
5V unless the output capacitor is replaced with a (C6)
higher voltage rating.
Table 1. Typical Values of Some Components
VOUT VIN R51
(Top Feedback Resistor)
R
(Bottom Feedback Resistor)
C12
(Cff) COUT
1.0V 1.0nF 100µF/6.3V 5V to 20V 10kΩ 40.2kΩ
1.2V 1.0nF 100µF/6.3V 5V to 20V 10kΩ 20.0kΩ
1.5V 1.0nF 100µF/6.3V 5V to 20V 10kΩ 11.5kΩ
1.8V 1.0nF 100µF/6.3V 5V to 20V 10kΩ 8.06kΩ
2.5V 1.0nF 100µF/6.3V 5V to 20V 10kΩ 4.75kΩ
3.3V 1.0nF 100µF/6.3V 5V to 20V 10kΩ 3.24kΩ
5V 7V 1.0nF 100µF/6.3V to 20V 10kΩ 1.91kΩ
March 12 , 2015 2 Revision 1.0
Micrel, Inc.
MIC45116 Evaluation Board
SW Node
A test pad (SW) is placed close to the module for
monitoring the switching waveform is one of the most . It
critical waveforms for the converter.
Current Limit
The MIC45116 uses the RDS(ON) -of the low side MOSFET
and external resistor connected from the ILIM pin to the
SW node to decide the current limit.
VIN
SW
ILIM
PGND
C5
R26
C16
PVIN
MIC45116
Figure 1 - . MIC45116 Current Limiting Circuit
In each switching cycle of the MIC45116, the inductor
current is sensed by monitoring the low-side MOSFET in
the OFF period. The sensed voltage (V(ILIM)) is compared
with the power ground (PGND) after a blanking time of
150ns. In this way the drop voltage over the R26 resistor
(VCL) is compared with the drop over the bottom FET
generating the short current limit. The small capacitor
(C16) connected from ILIM pin to PGND filters the
switching node ringing during the off time allowing a better -
short-limit measurement. The time constant created by
R26 and C16 should be much less than the minimum off
time.
The VCL drop allows programming of short limit through the
value of the resistor (R26) if the absolute value of the
voltage drop on the bottom FET is greater than V CL. In that
case the V(ILIM) is lower than PGND and a short circuit
event is triggered. A hiccup cycle to treat the short event is
generated. The hiccup sequence including the soft-start
reduces the stress on the switching FETs and protects the
load and supply for severe short conditions.
The short-circuit current limit can be programmed by using
Equation 3:
3 Eq.
where:
ICLIM = Desired current limit
RDS(ON) = On resistance of low- -side power MOSFET, 16mΩ
typically
VCL -= Current limit threshold (typical absolute value is
14mV per Electrical Characteristics in the MIC45116 data
sheet)
ICL -= Current limit source current (typical value is 80µA,
per Electrical Characteristics in the MIC45116 data sheet).
ΔIL(PP) - -= Inductor current peak to peak, since the inductor
is integrated, use Equation 4 to calculate the inductor
ripple current.
The peak peak inductor current ripple is:- -to
L f V
)V(VV
I
swIN(MAX)
OUTIN(MAX)OUT
L(PP) ××
−×
=∆
4 Eq.
The MIC45116 has 1.0µH inductor integrated into the
module. In case of hard short, the short limit is folded
down to allow an indefinite hard short on the output without
any destructive effect. It is mandatory to make sure that
the inductor current used to charge the output capacitance
during soft start is under the folded short limit; otherwise
the supply will go in hiccup mode and may not be finishing
the soft start successfully.
The MOSFET RDS(ON) varies 30% to 40% with temperature.
Therefore, it is recommended to add a 50% margin to ICLIM
in the above equation to avoid false current limiting due to
increased MOSFET junction temperature rise. With R26 =
1.62kΩ and C16 = 15pF, the typical output current limit is
about 8.2A.
March 12 , 2015 3 Revision 1.0


Product specificaties

Merk: Microchip
Categorie: Niet gecategoriseerd
Model: MIC45116-1YMP

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