The NCP1402 series are monolithic micropower step-up DC to DC
converter that are specially designed for powering portable equipment
from one or two cell battery packs.These devices are designed to
startup with a cell voltage of 0.8 V and operate down to less than
0.3V. With only three external components, this series allow a simple
means to implement highly efficient converters that are capable of up
to 200 mA of output current at Vin = 2.0 V, V
Each device consists of an on-chip PFM (Pulse Frequency
Modulation) oscillator, PFM controller, PFM comparator, soft-start,
voltage reference, feedback resistors, driver, and power MOSFET
switch with current limit protection. Additionally, a chip enable
feature is provided to power down the converter for extended battery
life.
The NCP1402 device series are available in the Thin SOT-23-5
package with five standard regulated output voltages. Additional
voltages that range from 1.8 V to 5.0 V in 100 mV steps can be
manufactured.
Features
•Extremely Low Startup Voltage of 0.8 V
•Operation Down to Less than 0.3 V
•High Efficiency 85% (V
•Low Operating Current of 30 A (V
= 2.0 V, V
in
OUT
OUT
•Output Voltage Accuracy ± 2.5%
•Low Converter Ripple with Typical 30 mV
•Only Three External Components Are Required
•Chip Enable Power Down Capability for Extended Battery Life
•Micro Miniature Thin SOT-23-5 Packages
•Pb-Free Packages are Available
Typical Applications
•Cellular Telephones
•Pagers
•Personal Digital Assistants (PDA)
•Electronic Games
•Portable Audio (MP3)
•Camcorders
•Digital Cameras
•Handheld Instruments
= 3.0 V.
OUT
= 3.0 V, 70 mA)
= 1.9 V)
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5
1
SOT23-5
(TSOP-5, SC59-5)
SN SUFFIX
CASE 483
PIN CONNECTIONS AND
MARKING DIAGRAM
1
CE
G
2
OUT
3
NC
(Top View)
xxx = Marking
A= Assembly Location
Y= Year
W= Work Week
G= Pb-Free Package
(Note: Microdot may be in either location)
ORDERING INFORMATION
See detailed ordering and shipping information in the ordering
information section on page 18 of this data sheet.
2OUTOutput voltage monitor pin, also the power supply pin of the device
3NCNo internal connection to this pin
4GNDGround pin
5LXExternal inductor connection pin to power switch drain
(1) The chip is enabled if a voltage which is equal to or greater than 0.9 V is applied
(2) The chip is disabled if a voltage which is less than 0.3 V is applied
(3) The chip will be enabled if it is left floating
LX
5
DRIVER
POWER
SWITCH
PFM
PFM
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2
NCP1402
ABSOLUTE MAXIMUM RATINGS
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Power Supply Voltage (Pin 2)V
Input/Output Pins
LX (Pin 5)
LX Peak Sink Current
CE (Pin 1)
Input Voltage Range
Input Current Range
Thermal Resistance, Junction-to-Air
Operating Ambient Temperature Range (Note 2)T
Operating Junction Temperature RangeT
Storage Temperature RangeT
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
NOTES:
1. This device series contains ESD protection and exceeds the following tests:
Human Body Model (HBM) ±2.0 kV per JEDEC standard: JESD22-A114.
Machine Model (MM) ±200 V per JEDEC standard: JESD22-A115.
2. The maximum package power dissipation limit must not be exceeded.
3. Latchup Current Maximum Rating: ±150 mA per JEDEC standard: JESD78.
4. Moisture Sensitivity Level: MSL 1 per IPC/JEDEC standard: J-STD-020A.
PD+
T
J(max)
R
JA
RatingSymbolValueUnit
6.0V
-0.3 to 6.0
400
-0.3 to 6.0
-150 to 150
250°C/W
-40 to +85°C
-40 to +125°C
-55 to +150°C
* T
OUT
V
LX
I
LX
V
CE
I
CE
R
JA
A
J
stg
A
V
mA
V
mA
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3
NCP1402
ELECTRICAL CHARACTERISTICS(For all values T
查询"NCP1402-D"供应商
= 25°C, unless otherwise noted.)
A
CharacteristicSymbolMinTypMaxUnit
OSCILLATOR
Switch On Time (current limit not asserted)t
Switch Minimum Off Timet
Maximum Duty CycleD
Minimum Startup Voltage (IO = 0 mA)V
Minimum Startup Voltage Temperature Coefficient (TA = -40°C to 85°C)
The NCP1402 series are monolithic power switching
regulators optimized for applications where power drain
must be minimized. These devices operate as variable
frequency, voltage mode boost regulators and designed to
operate in continuous conduction mode. Potential
Soft-Start
There is a Soft- Start circuit in NCP1402. When power is
applied to the device, the Soft- Start circuit pumps up the
output voltage to approximately 1.5 V at a fixed duty cycle, the
level at which the converter can operate normally. What is
more, the startup capability with heavy loads is also improved.
applications include low powered consumer products and
battery powered portable products.
The NCP1402 series are low noise variable frequency
voltage-mode DC-DC converters, and consist of Soft-Start
circuit, feedback resistor, reference voltage, oscillator, PFM
comparator, PFM control circuit, current limit circuit and
power switch. Due to the on-chip feedback resistor network,
the system designer can get the regulated output voltage
from 1.8 V to 5 V with a small number of external
components. The operating current is typically 30 A
(V
= 1.9 V), and can be further reduced to about 0.6 A
OUT
when the chip is disabled (VCE < 0.3 V).
The NCP1402 operation can be best understood by
examining the block diagram in Figure 2. PFM comparator
monitors the output voltage via the feedback resistor. When
the feedback voltage is higher than the reference voltage, the
power switch is turned off. As the feedback voltage is lower
than reference voltage and the power switch has been off for
at least a period of minimum off-time decided by PFM
Regulated Converter Voltage (V
The V
is set by an internal feedback resistor network.
OUT
This is trimmed to a selected voltage from 1.8 to 5.0 V range
in 100 mV steps with an accuracy of $2.5%.
Current Limit
The NCP1402 series utilizes cycle-by-cycle current
limiting as a means of protecting the output switch
MOSFET from overstress and preventing the small value
inductor from saturation. Current limiting is implemented
by monitoring the output MOSFET current build-up during
conduction, and upon sensing an overcurrent conduction
immediately turning off the switch for the duration of the
oscillator cycle.
The voltage across the output MOSFET is monitored and
compared against a reference by the VLX limiter. When the
threshold is reached, a signal is sent to the PFM controller
block to terminate the power switch conduction. The current
limit threshold is typically set at 350 mA.
OUT
)
oscillator, the power switch is then cycled on for a period of
on-time also decided by PFM oscillator, or until current
limit signal is asserted. When the power switch is on, current
ramps up in the inductor, storing energy in the magnetic
field. When the power switch is off, the energy in the
magnetic field is transferred to output filter capacitor and the
load. The output filter capacitor stores the charge while the
inductor current is high, then holds up the output voltage
until next switching cycle.
Enable / Disable Operation
The NCP1402 series offer IC shut-down mode by chip
enable pin (CE pin) to reduce current consumption. An
internal pullup resistor tied the CE pin to OUT pin by default
i.e. user can float the pin CE for permanent “On”. When
voltage at pin CE is equal or greater than 0.9 V, the chip will
be enabled, which means the regulator is in normal
operation. When voltage at pin CE is less than 0.3 V, the chip
is disabled, which means IC is shutdown.
Important: DO NOT apply a voltage between 0.3 V and 0.9 V to pin CE as this is the CE pin's hyteresis voltage
range. Clearly defined output states can only be obtained by applying voltage out of this range.
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NCP1402
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APPLICATIONS CIRCUIT INFORMATION
V
in
C1
10 F
CE
OUT
NC
47 H
1
NCP1402
2
3
Figure 59. Typical Application Circuit
Step-up Converter Design Equations
NCP1402 step-up DC-DC converter designed to operate
in continuous conduction mode can be defined by:
CalculationEquation
2
V
L
I
PK
I
min
t
off
Q
V
ripple
*NOTES:
I
- Peak inductor current
PK
I
- Minimum inductor current
min
I
- Desired dc output current
O
I
- Desired maximum dc output current
Omax
I
- Average inductor current
L
Vin- Nominal operating dc input voltage
V
- Desired dc output voltage
OUT
VF- Diode forward voltage
VS- Saturation voltage of the internal FET switch
Q- Charge stores in the C
V
- Output ripple voltage
ripple
ESR - Equivalent series resistance of the output capacitor
M- An empirical factor, when V
M = 8 x 10-6, otherwise M = 5.3 x 10-6.
v M
(Vin* Vs)t
(ton) t
t
[
C
off)IO
off
(V
OUT
(IL* IO)t
Q
OUT
OUT
in
ǒ
V
OUTIOmax
on
) I
L
*
(Vin* Vs)t
min
(Vin* VS)t
2L
on
) VF* Vin)
off
) (IL* IO)ESR
during charging up
≥ 3.0 V,
OUT
Ǔ
on
EXTERNAL COMPONENT SELECTION
Inductor
The NCP1402 is designed to work well with a 47 H
inductor in most applications. 47 H is a sufficiently low
value to allow the use of a small surface mount coil, but large
L1
LX
5
GND
4
D1
V
C2
68 F
OUT
enough to maintain low ripple. Low inductance values
supply higher output current, but also increase the ripple and
reduce efficiency. Note that values below 27 H is not
recommended due to NCP1402 switch limitations. Higher
inductor values reduce ripple and improve efficiency, but
also limit output current.
The inductor should have small DCR, usually less than 1
to minimize loss. It is necessary to choose an inductor with
saturation current greater than the peak current which the
inductor will encounter in the application.
Diode
The diode is the main source of loss in DC-DC converters.
The most importance parameters which affect their
efficiency are the forward voltage drop, VF, and the reverse
recovery time, trr. The forward voltage drop creates a loss
just by having a voltage across the device while a current
flowing through it. The reverse recovery time generates a
loss when the diode is reverse biased, and the current appears
to actually flow backwards through the diode due to the
minority carriers being swept from the P-N junction. A
Schottky diode with the following characteristics is
recommended:
Small forward voltage, VF < 0.3 V
Small reverse leakage current
Fast reverse recovery time/ switching speed
Rated current larger than peak inductor current,
I
> I
rated
PK
Reverse voltage larger than output voltage,
V
> V
reverse
OUT
Input Capacitor
The input capacitor can stabilize the input voltage and
minimize peak current ripple from the source. The value of
the capacitor depends on the impedance of the input source
used. Small Equivalent Series Resistance (ESR) Tantalum or
ceramic capacitor with value of 10 F should be suitable.
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NCP1402
Output Capacitor
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The output capacitor is used for sustaining the output
voltage when the internal MOSFET is switched on and
smoothing the ripple voltage. Low ESR capacitor should be
used to reduce output ripple voltage. In general, a 47 uF to
68 uF low ESR (0.15 to 0.30 ) Tantalum capacitor
should be appropriate. For applications where space is a
critical factor, two parallel 22 uF low profile SMD ceramic
capacitors can be used.
An evaluation board of NCP1402 has been made in the
size of 23 mm x 20 mm only, as shown in Figures 60 and 61.
Please contact your ON Semiconductor representative for
availability. The evaluation board schematic diagram, the
artwork and the silkscreen of the surface mount PCB are
shown below:
One point grounding should be used for the output power
return ground, the input power return ground, and the device
switch ground to reduce noise as shown in Figure 62, e.g.:
C2 GND, C1 GND, and U1 GND are connected at one point
in the evaluation board. The input ground and output ground
traces must be thick enough for current to flow through and
for reducing ground bounce.
Power Signal Traces
Low resistance conducting paths should be used for the
power carrying traces to reduce power loss so as to improve
TP1
V
in
CE
1
OUT
2
NC
3
10 F/16 V
TP4
GND
++
C1
JP1
Enable
On
Off
efficiency (short and thick traces for connecting the inductor
L can also reduce stray inductance), e.g.: short and thick
traces listed below are used in the evaluation board:
1. Trace from TP1 to L1
2. Trace from L1 to Lx pin of U1
3. Trace from L1 to anode pin of D1
4. Trace from cathode pin of D1 to TP2
Output Capacitor
The output capacitor should be placed close to the output
terminals to obtain better smoothing effect on the output
ripple.
*For additional information on our Pb-Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
The product described herein (NCP1402), may be covered by the following U.S. patents: 6,518,834. There may be other patents pending.
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.
“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All
operating parameters, including “Typicals” must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights
nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications
intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should
Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,
and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death
associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal
Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT:
Literature Distribution Center for ON Semiconductor
P.O. Box 5163, Denver, Colorado 80217 USA
Phone: 303-675-2175 or 800-344-3860 Toll Free USA/Canada
Fax: 303-675-2176 or 800-344-3867 Toll Free USA/Canada
Email: orderlit@onsemi.com
N. American Technical Support: 800-282-9855 Toll Free
USA/Canada
Europe, Middle East and Africa Technical Support:
Phone: 421 33 790 2910
Japan Customer Focus Center
Phone: 81-3-5773-3850
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ON Semiconductor Website: www.onsemi.com
Order Literature: http://www.onsemi.com/orderlit
For additional information, please contact your local
Sales Representative
NCP1402/D
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