EVBUM2157/D - 495.0 KB

NCP102MBGEVB
NCP102 4 W Motherboard
Evaluation Board User's
Manual
Introduction
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The NCP102 low dropout linear regulator controller
contains all the control and protection features needed to
implement a low voltage regulator. The required external
N−Channel MOSFET allows the device to be used in
applications across a broad range of voltage and power levels.
The NCP102 is the ideal choice for new generation low
voltage supplies in computing motherboard and consumer
applications thanks to the following features:
• A dedicated enable input: allows the controller to be
remotely enabled or sequenced.
• An extremely accurate 0.8 V (+2.0%) reference:
allows the implementation of sub 1 V voltage supplies.
• Adjustable soft−start: allows the system to turn on in
a controlled manner eliminating output voltage
overshoot.
• Minimum drive capability of +5 mA: provides fast
transient response. The drive current is internally
limited to protect the controller in case of an external
MOSFET failure.
• Wide voltage supply operation: allows the controller
to be biased directly from existing voltage supplies
without the need of external voltage limiting circuits.
EVAL BOARD USER’S MANUAL
Figure 2. Evaluation Board Photo
Stability of linear regulators is very critical as with any
feedback system. The main contributors to the stability of a
linear regulator are the error amplifier, the external pass
transistor, the output capacitor(s) and load. Figure 3 shows
a model of a linear regulator used to evaluate the frequency
response of the regulator.
Linear Regulators
Linear regulators are a common topology for generating
a lower voltage supply from a higher voltage. A linear
regulator consists of a voltage reference (VREF), an error
amplifier and a pass transistor as shown in Figure 1.
Vin
VDRV
Vout
Pass Transistor
Rg
Cgs
Error Amplifier
Cout
VREF
Error Amplifier
R2
A fraction of the output voltage is compared to the internal
reference voltage by means of resistor divider R1 and R2.
The minimum output voltage is limited by the voltage
reference. The pass transistor is selected to achieve the
desired input voltage and output current.
November, 2012 − Rev. 1
EA(s)
VREF
Vgs
_
gmVgs
Vout
R1
−
+
Figure 1. Simplified Linear Regulator Model
© Semiconductor Components Industries, LLC, 2012
Cgd
+
R1
−
+
Vin
System
Cout1
Cout2
Rout
R2
Gdiv(s)
RESR1
RESR2
T(s)
Figure 3. Frequency Model of a Linear Regulator
1
Publication Order Number:
EVBUM2157/D
NCP102MBGEVB
The overall system response, H(s), is given by Equation 1.
H(s) + EA(s) @ G div(s) @ T(s)
The frequency response of the external components from
VDRV to Vout is a little more complicated. The response is
determined by the output capacitors and the external pass
transistor. If only one capacitor is considered the transfer
response can be simplified as described in
ON Semiconductor’s application note AND8037.
(eq. 1)
The error amplifier (EA(s)) usually has a dominant pole
at a low frequency with additional poles or zeros at higher
frequencies. Assuming its additional frequency components
are above the frequency range of interest, the frequency
response can be approximated to a single pole response as
given by Equation 2.
EA(s) +
K1
(s ) p1)
Each output capacitor contributes a zero due to its
equivalent series resistance (ESR). In the case of two types
of output capacitors (such as electrolytic and ceramic), zeros
at different frequencies are generated. The external pass
transistor contributes a zero and affects the poles of the
system. The frequency response from VDRV to Vout is given
by Equation 4.
(eq. 2)
where K1 is the dc gain and p1 is the dominant pole. The
resistor divider attenuates the system gain, Gdiv(s), and its
magnitude is given by Equation 3.
ǒR1 R2
Ǔ
) R2
G div(s) + 20 @ log
T(s) +
(eq. 3)
R out(sC gs ) 1) @ (sR ESR1C OUT1 ) 1) @ (sR ESR2C OUT2 ) 1)
D 4s 4 ) D 3s 3 ) D 2s 2 ) D 1s ) (1 ) g mR out)
(eq. 4)
where:
D4 = CgsRoutCgdRgRX
D3 = CgsRoutCgdRgRX + RgRXCX + CXRoutRgRESR2Cout2Cout1 + RoutRgRESR1Cout1Cout2CX + RoutRX(RggmCgd + Cgs)
D2 = CgsRoutCgdRg + RgRESR1Cout1CX + RX + RESR2Cout2RgCX + Cout1RoutRESR2Cout2 + Cout1RoutRgCX +
D2 = Cout2RoutRESR1Cout1 + Cout2RoutRgCX + gmRoutRX + gmRoutRgCgdRS + CgsRoutRS
D1 = RgCX + RS + Rout (Cout1 + Cout2 + Cgs) + gmRout(RS + CgdRg)
RX = RESR1Cout1RESR2Cout2
CX = Cgs + Cgd
RS = RESR1Cout1 + RESR2Cout2
and gm is the transconductance of the external transistor.
is available for the NCP102 allowing the user to evaluate the
It is obvious that the overall transfer response is too
system response. The design tool can be downloaded at
complex for hand calculations. Even with several
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simplifications the roots of the transfer function to
determine the poles of T(s) are too complex. A design tool
DESIGN EXAMPLE
The flexibility of the NCP102 is demonstrated by
designing a 1.2 V/3.0 A voltage regulator using the NCP102
design tool. The input and supply voltages selected are
typically found in computing mother board applications.
The regulator specifications are listed in Table 1.
Table 1. Design Specifications
Parameter
Symbol
Min
Max
Input Voltage
Vin (V)
1.8 (±2%)
Output Voltage
Vout (V)
1.2 (±2%)
Output Current
Iout (A)
0.3
3.0
Ambient Temperature
TA (°C)
−
50
Supply Voltage
VCC (V)
5 V (±5%)
Derating Factor
−
90 %
DESIGN PROCEDURE
External MOSFET:
V th v V CC * V out
The 1st step in the regulator design is to select the external
pass transistor. The output and supply voltages as well as
MOSFET gate−to−source threshold voltage, Vth, need to be
considered. The MOSFET threshold voltage, Vth, should be
less than VCC minus Vout as given by Equation 5.
(eq. 5)
Solving 5 using the design specifications, Vth should be
less than 3.8 V. The next step is to calculate the power
dissipation, PD, of the external MOSFET. The power
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NCP102MBGEVB
dissipation is calculated using Equation 6 and the maximum
junction temperature, TJ, using Equation 7.
(eq. 6)
T J + P D @ R qJA ) T A
(eq. 7)
where, RqJA is the junction to ambient thermal resistance (in
°C/W) of the external MOSFET. The NCP102 design tool
automatically calculates the power dissipation and junction
temperature.
Using RqJA doesn’t always result in accurate junction
temperature calculations as RqJA depends on the board
layout. Alternatively, TJ can be calculated using the junction
to case thermal resistance, RqJC, and measuring the case
temperature (TC). Equation 8 relates the TJ to RqJC.
T J + P D @ R qJC ) T C
Resistor Divider:
The output voltage is sampled by resistor divider R1 and
R2. The node between the resistors must equal the reference
voltage (0.8 V) at the desired output voltage. Using the
design tool, the user arbitrarily selects a value for R2 and the
tool suggests a value for R1. The user can override the
suggested R1 value. In this design, R2 is set at 20 kW and R1
at 10 kW.
(eq. 8)
ON Semiconductor’s NTD40N03 is used in this design. It
has a Vth of 2.0 V, an RqJA of 71.4°C/W and an RqJC of
3°C/W. Using RqJA and the maximum ambient temperature
a TJ of 178°C is calculated. That is slightly higher than the
maximum junction temperature of the device and exceeds
the derating factor. As RqJA provided in the NTD40N03
datasheet is for a specific layout, we will evaluate the board
at full load and use RqJC to calculate TJ. It will be shown that
the junction temperature meets the derating factor. This
board provides a place holder for a parallel MOSFET (Q2)
allowing the user to spread the power dissipation if needed.
Transconductance is the ratio of output current to the input
voltage. In a MOSFET, it is the ratio of drain current (ID) to
gate−to−source voltage (VGS) as given by Equation 9.
The NCP102 design tool simplifies the frequency response
analysis of the regulator. It is a good tool to evaluate the
interaction between the components and approximate the
cross over frequency. However, it does not take into account
2nd order effects such as transconductance variations with
load current. The simulated frequency response of the
regulator at minimum load is shown in Figure 4.
MAGNITUDE (dB)
DI D
gm +
DV GS
Frequency Response:
(eq. 9)
Referring to the NTD40N03R datasheet, the
transconductance is calculated using the On−Region
Characteristics Curve (Figure 1). Let’s calculate the
transconductance for a VDS of 0.5 V with a VGS variation
from 2.8 V to 3 V. The drain current at 2.8 V is ~1.8 A and
at 3 V it is approximately 3.8 A. Using these values a
transconductance of 10 is calculated.
The gate−to−source, CGS, and drain−to−source, CDS,
capacitances are needed for the frequency response analysis.
The capacitances are calculated from the Capacitance
Variation curve on the NTD40N03R datasheet. Crss is the
gate−to−drain capacitance. Ciss is the sum of CGS and CGD.
Coss is the sum of CDS and CGD. Referring to the
Capacitance Variation curve, Crss is approximately 150 pF,
Ciss is approximately 700 pF and Coss is approximately
600 pF at a VDS of 0.5 V, resulting in a CDS of 450 pF and
a CGS of 550 pF.
40
180
30
135
Simulated Phase
20
90
10
45
0
0
−45
−10
−90
−20
Simulated Gain
−30
−40
PHASE (°)
P D + (V in * V out) @ I out
An electrolytic capacitor has high capacitance and high
ESR resulting in a zero at a low frequency (typically below
1 kHz) and a dominant pole at a higher frequency. The
ceramic capacitor has very low ESR placing a zero at a high
frequency. If the ceramic capacitor capacitance is large
(above 4.7 mF) the resulting zero may be in the crossover
frequency range and thus affect the stability of the system.
This design uses a 1000 mF electrolytic capacitor with an
ESR of 212 mW and a 4.7 mF ceramic in parallel.
1
10
100
FREQUENCY (kHz)
−135
−180
1000
Figure 4. Simulated Frequency Response
The approximate crossover frequency is 50 kHz with a
phase margin of 85°.
Soft−Start:
Soft−start slowly increases the regulator output voltage
reducing stress during power up. The NCP102 implements
soft−start by slowly charging the soft−start capacitor
(CSOFT−S) with a fixed current source (ISOFT−S). The
soft−start voltage is then used to control the dv−dt of the
DRV pin. The soft−start period ends once the soft−start
voltage reaches 0.8 V. Equation 10 is used to calculate the
soft−start period.
Output Capacitor:
The next step is to select the output capacitor. It is very
common to use an electrolytic capacitor for bulk storage and
a ceramic capacitor for high frequency bypass. However, the
capacitors need to be carefully selected as they affect the
stability of the system.
t SOFT*S +
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C SOFT*S @ 0.8 V
I SOFT*S
(eq. 10)
NCP102MBGEVB
The design tool calculates the soft−start capacitor based
on the user provided soft−start period. The user can override
the suggested soft−start capacitor value and the tool
calculates the soft−start period based on the provided
capacitor value. This design uses a 0.1 mF soft−start
capacitor for a 16 ms period.
BOARD LAYOUT
The regulator is built to validate the design using a 2 layer
FR4 board having 1 oz copper plating. The board size is
3.5 in. x 3.2 in. Test points are provided for the Enable, DRV,
Soft−Start, FB, Vin, Vout signals.
During the layout process care was taken to:
1. Minimize trace length, especially for high current
loops.
2. Use wide traces for high current connections.
3. Use a single ground connection.
4. Place decoupling capacitors close to the NCP102
and board terminals.
5. Sense output voltage at the output connector to
improve load regulation.
The top layer is shown in Figure 5 and the bottom layer is
shown in Figure 6. The top layer shows the component
location.
The layout files may be available. Please contact your
sales representative for availability.
Figure 6. Layer 2 (Bottom)
Figure 5. Layer 1 (Top)
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NCP102MBGEVB
DESIGN VALIDATION
The circuit schematic is shown in Figure 7 and the bill of
materials is shown in Table 2.
Figure 7. Circuit Schematic
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NCP102MBGEVB
Table 2. BILL OF MATERIALS
Substitutions
Allowed
Lead
Free
VJ0603Y103KXXA
(C1608X7R1H103K)
Yes
Yes
Vishay
(TDK)
VJ0603Y101KXXA
(C1608C0G1H101J)
Yes
Yes
1206
TDK
C3216X5R1C475K
Yes
Yes
10%
1206
Vishay
(TDK)
VJ1206Y104KXXA
(C3216CH1E104J)
Yes
Yes
1000 uF, 25 V
20%
Radial
Lead
United-Chemic
on
ESMG250ELL102MJ20S
No
Yes
Capacitor,
Aluminum
Electrolytic
470 uF, 25 V
20%
Radial
Lead
United-Chemic
on
ESMG250ELL471MJC5S
Yes
Yes
1
Power MOSFET,
N-Channel
45 A, 25 V
n/a
D-Pack
ON
Semiconductor
NTD40N03R
No
Yes
n/a
D-Pack
Do Not Place
Yes
Q3
1
Transistor, Sm
Signal, NPN
200 mA, 40 V
n/a
SOT-23
ON
Semiconductor
MMBT3904LT1G
Yes
Yes
R1
1
Resistor, Thick Film
200 W, 0.25 W
1%
1206
Vishay
CRCW1206200RF
Yes
Yes
R2
1
Resistor, Thick Film
100 W, 0.25 W
1%
1206
Vishay
CRCW1206100RF
Yes
Yes
R3
1
Resistor, Thick Film
10 kW, 0.25 W
1%
1206
Vishay
CRCW12061002F
Yes
Yes
R4
1
Resistor, Thick Film
20 kW, 0.25 W
1%
1206
Vishay
CRCW12062002F
Yes
Yes
R5
1
Resistor, Thick Film
0 W, 0.1 W
0603
Vishay
CRCW06030R00F, or
CRCW06030000Z0
Yes
Yes
R6
1
Resistor, Thick Film
10 kW, 0.1 W
1%
0603
Vishay
CRCW06031002F
Yes
Yes
R7
1
Resistor, Thick Film
365 kW, 0.1 W
1%
0603
Vishay
CRCW06033653F
Yes
Yes
R8
1
Resistor, Thick Film
1000 W, 0.25 W
1%
1206
Vishay
CRCW12061001F
Yes
Yes
U1
1
Controller, Low
Dropout Linear
Regulator
TSOP-6
ON
Semiconductor
NCP102G
No
Yes
3.5” x 3.2”
x 0.062”
Circuit
Express, Inc.
NCP102_DEMOBD
Yes
Yes
Designator
Tolerance
Footprint
Manufacturer
Manufacturer Part
Number
Qty
Description
Value
C1, C3
2
Capacitor, Ceramic
.01 uF, 25 V
(.01 uF, 50 V)
10%
0603
Vishay
(TDK)
C4,
C11
2
Capacitor, Ceramic
100 pF, 25 V
(100 pF, 50 V)
5%
0603
C5, C8
2
Capacitor, Ceramic
4.7 uF, 16 V
10%
C6, C9
2
Capacitor, Ceramic
.1 uF, 25 V
C7
1
Capacitor,
Aluminum
Electrolytic
C10
1
Q1
Q2
Do Not Place
C2
Not Used
Hardware
H1
1
Printed Circuit
Board
J1
1
Banana Jack,
4 mm Socket,
Brown,
Horizontal Mt.
10 ADC
n/a
10.5mm x
23.5mm x
12.4mm;
15.3mm
lead pitch
Deltron Emcon
571-0300
Yes
Yes
J2
1
Banana Jack,
4 mm Socket,
Red,
Horizontal Mt.
10 ADC
n/a
10.5mm x
23.5mm x
12.4mm;
15.3mm
lead pitch
Deltron Emcon
571-0500
Yes
Yes
J3
1
Banana Jack,
4 mm Socket,
Yellow,
Horizontal Mt.
10 ADC
n/a
10.5mm x
23.5mm x
12.4mm;
15.3mm
lead pitch
Deltron Emcon
571-0700
Yes
Yes
J4, J6
2
Banana Jack,
4 mm Socket,
Black,
Horizontal Mt.
10 ADC
n/a
10.5mm x
23.5mm x
12.4mm;
15.3mm
lead pitch
Deltron Emcon
571-0100
Yes
Yes
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NCP102MBGEVB
Table 2. BILL OF MATERIALS
Substitutions
Allowed
Lead
Free
DigiKey ED1930-ND,
or equiv
Yes
Yes
Components
Corporation
TP-015-01-01
Yes
Yes
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-02
Yes
Yes
Test Point, Orange
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-03
Yes
Yes
1
Test Point, Yellow
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-04
Yes
Yes
TP5
1
Test Point, Green
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-05
Yes
Yes
TP6
1
Test Point, Blue
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-06
Yes
Yes
TP7
1
Test Point, Violet
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-07
Yes
Yes
TP8,
TP9,
TP10,
TP11
4
Test Point, Black
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-00
Yes
Yes
TP12
1
Test Point, Gray
.18”ht x
.05”dia
eyelet
Components
Corporation
TP-015-01-08
Yes
Yes
TP6a,
TP2a
2
3.5 mm dia Probe
Adapter
Tektronix
131-5031-00
(pkg of 25)
Yes
Yes
Designator
Qty
Description
Value
Tolerance
J5
1
Terminal Block,
2 Pole, Side Entry
300 V, 16 A
n/a
TP1
1
Test Point, Brown
.18”ht x
.05”dia
eyelet
TP2
1
Test Point, Red
TP3
1
TP4
Footprint
Manufacturer
10mm x
10mm x
13.5mm;
5mm lead
pitch
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Manufacturer Part
Number
NCP102MBGEVB
Startup:
The final step is to verify the board performance. The
evaluation criteria include step load and power up responses,
load regulation, stability and power dissipation.
The startup behavior of the regulator is evaluated at
minimum and maximum load enabling the controller using
the enable pin while Vin and VCC are already high. The
startup waveforms at minimum and maximum load are
shown in Figure 9 and 10, respectively.
Dynamic Response:
The dynamic response of the regulator is evaluated
stepping the load current from 10% to 100% and from 100%
to 10% of the rated output current. The step load responses
are shown in Figure 8.
Vout
Enable
Vin
Soft−start
Figure 10. Output Voltage During Power Up at
Maximum Load
Figure 8. Output Voltage Response to a Step Load
from 0.3 A to 3.0 A to 0.3 A
Line and Load Regulation:
Line and load regulation are calculated using Equations 11
and 12, respectively. Line regulation is measured at 0.1%
and load regulation is measured at 0.067%. The output
voltage vs. input voltage and output load is shown in
Figure 11.
The output voltage stays within the 2% tolerance limit.
The initial drop on the output voltage as a higher load is
applied is mostly dependent on the output capacitor and not
on the loop response of the system. No ringing is observed,
indicating an adequate phase margin.
Reg (line) +
Vout
Reg (load) +
Enable
DV out
DV in
(eq.
11)
V out(no load) * V out(full load)
V out(no load)
(eq. 12)
1.224
Vout, OUTPUT VOLTAGE (V)
Vin
1.216
1.208
Soft−start
Iout = 3.0 A
1.200
Iout = 0.3 A
1.192
1.184
Figure 9. Output Voltage During Power Up at
Minimum Load
1.176
1.55
1.65
1.75
1.85
Vin, INPUT VOLTAGE (V)
1.95
Figure 11. Output Voltage Response to Input
Voltage and Output Load Variations
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2.05
NCP102MBGEVB
Frequency Response:
evaluated using an infrared camera. Figure 13 shows the
thermal image of the board at maximum output load.
The open loop response is measured by injecting an AC
signal across R2 using a network analyzer and an isolation
transformer. The measured and calculated open loop
responses at minimum load are shown in Figure 12. The
measured crossover frequency is 58 kHz with a phase
margin of 70°. A good correlation is observed between
simulated and calculated responses up to around 200 kHz.
40
180
135
Simulated Phase
20
90
10
45
0
0
Measured Phase
−10
Figure 13. Thermal Image of the Board at
Maximum Load
−45
−90
−20
Simulated Gain
−30
−40
PHASE (°)
MAGNITUDE (dB)
30
Measured Gain
1
10
100
FREQUENCY (kHz)
As expected, the hottest component on the board is the
external pass transistor. The case temperature is measured at
78.4°C at room temperature. Using Equation 8, the junction
temperature is calculated at 84°C. The maximum junction
temperature is calculated at 109°C assuming a 25°C
temperature delta between room and maximum ambient
temperatures. A junction temperature of 109°C meets our
derating guidelines.
The thermal performance of the board can be optimized
by using a heatsink, increasing the number of external pass
transistors (Q1 & Q2) pad area, increasing the copper weight
of the board or using an additional pass transistor.
−135
−180
1000
Figure 12. Measured and Calculated Open
Loop Frequency Responses
Power Dissipation:
This demo board is designed to operate with no airflow.
However, in most desktop computing applications airflow
will be present. The thermal performance of the board is
SUMMARY
A 1.2 V regulator is designed and built using the NCP102.
The regulator has excellent line and load regulation with
better than ±2% output voltage regulation.
The regulator provides excellent transient response.
Phase margin and crossover frequency are measured at 70°
and 58 kHz, respectively.
REFERENCES
1. Tod Schiff, “Stability in High Speed Linear LDO
Regulator,” AND8037/D, www.onsemi.com.
2. Low Dropout Linear Regulator Controller Datasheet
NCP102, www.onsemi.com.
3. Power MOSFET 45 A, 25 V Datasheet NTD40N03R,
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TEST PROCEDURE FOR THE NCP102 EVALUATION BOARD
Required Equipment
• 3 DC Power Supplies:
♦
♦
♦
•
“Vin supply” possessing a minimum voltage rating
of 5 VDC and minimum current rating of 4 ADC;
for example, HP 6282A.
“Vcc supply” possessing a minimum voltage rating
of 15 VDC and minimum current rating of 1 ADC;
for example, 1/2 Agilent e3649A dual supply.
“N_Enable supply” possessing a minimum voltage
rating of 5.5 VDC and minimum current rating of
•
0.1 ADC; for example, 1/2 Agilent e3649A dual
supply.
3 Auto-ranging Digital Multimeters (DMMs): each
possessing a minimum voltage rating of 20 VDC and
minimum current rating of 2ADC; for example,
Keithley 175.
1 Electronic Load: possessing a current display and
minimum current capability of 4 ADC; for example,
Kikusui PLZ303W.
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NCP102MBGEVB
HP6282A
DC Supply
Agilent e3649
Dual DC Supply
5.0−12.0VDC 0−5.5VDC
+ −
+ −
1.8V/ 4ADC
+ −
+ −
Keithley 175 DMM
DMM 2
NCP102 Evaluation Board
GND
Vin
GND
N_Enable
Vcc
+ −
Keithley 175 DMM
Vout
DMM 1
DMM 3
+ −
Keithley 175 DMM
Kikusui
PLZ 303W DC Load
+ −
Figure 14. Test Setup
Test Procedure
5. Verify that Vout (DMM 3) equals 1.200 VDC,
±2% (1.176 VDC to 1.224 VDC).
6. Reconnect the banana cable to “N_Enable”, or
adjust the “N_Enable” supply output to 4.5 VDC.
7. If Vcc= 12.0 VDC (DMM 1), go to Full-Load
Regulation and Enable Function, below.
8. Adjust the Vcc supply to 12.0 VDC, as indicated
on DMM 1.
9. Repeat steps 1 through 7 of this section.
• Establish Setup
1. Connect the NCP102 Evaluation Board as shown
in Figure 14.
2. Adjust the N_Enable supply to 4.5 VDC while
observing the indicator on the supply.
NOTE: for measurement accuracy, the DMMs must be
connected to the Evaluation Board terminals and
not the DC supply or load terminals. This is
particularly true for DMM 2 and DMM 3.
3. Connect DMM 1 to Vcc and configure as a
voltmeter. Set DMM 1for auto-range.
4. Connect DMM 2 to Vin and configure as a
voltmeter. Set DMM 2 for auto-range.
5. Connect DMM 3 to Vout and configure as a
voltmeter. Set DMM 3 for auto-range.
6. Adjust the Vcc supply to 5.0 VDC while observing
DMM 1 (not the indicator on the DC supply).
7. Adjust the Vin supply to 1.800 VDC while
observing DMM 2 (not the indicator on the DC
supply).
8. Disable the electronic load so that it is neither
sinking nor sourcing current.
• Full-Load Regulation and Enable Function
1. While observing the front panel indicator on the
electronic load, adjust it to sink 3.5 ADC from the
demonstration board Vout terminal.
2. Enable the electronic load.
3. Verify that Vout (DMM 3) equals zero VDC.
4. Temporarily disconnect the banana cable
connected to “N_Enable”, or reduce the
“N_Enable” supply to zero Volts.
5. Verify that Vin (DMM 2) equals 1.800 VDC, ±2%
(1.764 VDC to 1.836 VDC).
6. Readjust the Vin supply if necessary.
7. Verify that Vout (DMM 3) equals 1.200VDC, ±2%
(1.176 VDC to 1.224 VDC).
8. Reconnect the banana cable to “N_Enable”, or
adjust the “N_Enable” supply output to 4.5 VDC.
9. If Vcc= 5.0 VDC (DMM 1), go to Step 12.
10. Adjust the Vcc supply to 5.0VDC, as indicated on
DMM 1.
11. Repeat steps 1 through 9 of this section.
12. Verify that Vout (DMM 3) equals zero VDC.
13. Test complete.
• No-Load Regulation and Enable Function
1. Verify that Vout (DMM 3) equals zero VDC.
2. Temporarily disconnect the banana cable
connected to “N_Enable”, or reduce the
“N_Enable” supply to zero Volts.
3. Verify that Vin (DMM 2) equals 1.800 VDC, ±2%
(1.764 VDC to 1.836 VDC).
4. Readjust the Vin supply if necessary.
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NCP102MBGEVB
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