NCP1423, SCV1423
Boost Converter Sync-Rect,
PFM, DC-DC, True-Cutoff,
Ring-Killer 400 mA
NCP1423 is a monolithic micropower high frequency step−up
switching converter IC specially designed for battery operated hand
−held electronic products. It integrates Synchronous Rectifier for
improving efficiency as well as eliminating the external Schottky
Diode. High switching frequency (up to 600 kHz) allows low profile
inductor and output capacitor being used. When the IC is disabled,
internal conduction path from LX or BAT to OUT is blocked, OUT pin
is isolated from the battery. This achieves True−Cutoff. Ring−Killer is
also integrated to eliminate the high frequency ringing in discontinuous
conduction mode. Low−Battery Detector, Cycle−by−Cycle Current
Limit, Overvoltage Protection and Thermal Shutdown provide value
−added features for various battery operated application. With all of
these functions ON, the quiescent supply current is only 9.0 mA. This
device is available in compact Micro10 package.
Features
• High Efficiency: 92% for 3.3 V Output@ 400 mA from 2.5 V Input
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
87% for 1.8 V Output@ 70 mA from 1.2 V Input
High Switching Frequency, up to 600 kHz (not hitting current limit)
Low Quiescent Current of 9.0 mA
Low Battery Detector
0.8 V Startup
External Adjustable Output Voltage
±1.5% Output Voltage Accuracy
Ring−Killer for Discontinuous Conduction Mode
Thermal Shutdown
1.2 A Cycle−by−Cycle Current Limit
Output Current up to 400 mA @ VOUT = 3.3 V,
200 mA @ VOUT = 1.8 V
Overvoltage Protection
Low Profile and Minimum External Part
Open Drain Low−Battery Detector Output
Compact Micro10 Package
SCV Prefix for Automotive and Other Applications Requiring
Unique Site and Control Change Requirements; AEC−Q100
Qualified and PPAP Capable
These Devices are Pb−Free and are RoHS Compliant
Typical Applications
•
•
•
•
•
•
Wireless Optical Mouse
Wireless Headsets
Internet Audio Players
Personal Digital Assistants (PDAs)
Hand−held Instruments
Conversion from one/two NiMH or NiCd cells to 1.8 V / 3.3 V
© Semiconductor Components Industries, LLC, 2014
August, 2019 − Rev. 8
1
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MARKING
DIAGRAM
Micro10
DM SUFFIX
CASE 846B
XXX
AYWG
G
XXX
= DAR (NCP1423)
= GEN (SCV1423)
A
= Assembly Location
Y
= Year
W
= Work Week
G
= Pb−Free Package
(Note: Microdot may be in either location)
PIN CONNECTIONS
EN
1
REF
2
10 LBO
Micro10
9
LBI
8
ADEN
FB
3
GND
4
7
LX
OUT
5
6
BAT
(Top View)
ORDERING INFORMATION
Device
Package
Shipping†
NCP1423DMR2G
Micro10
(Pb−Free)
4000 Tape & Reel
SCV1423DMR2G
Micro10
(Pb−Free)
4000 Tape & Reel
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specifications
Brochure, BRD8011/D.
Publication Order Number:
NCP1423/D
NCP1423, SCV1423
ON
OFF
C1
100k
EN
*
LBO
REF
R1
0.2 mF
22 mF
COUT
R3
LBI
FB
R2
Low battery
open drain output
ON
OFF
ADEN
GND
LX
OUT
BAT
R4
Low battery
sense input
5.6 mH
10 mF
CIN
NCP1423, SCV1423
* Optional
Figure 1. Typical Operation Circuit
PIN DESCRIPTION
Pin No.
Symbol
Description
1
EN
Low−Battery Detector Input and Enable. With this pin pulled down below 0.5 V, the device will be disabled
and will enter shutdown mode
2
REF
1.195 V Reference Voltage Output, bypass with 0.1 mF capacitor if this pin is not loaded, with a 1.0 mF
bypassing capacitor, this pin can be loaded up to 2.5 mA @ VOUT = 3.3 V.
3
FB
4
GND
Output Voltage Feedback Input
Ground
5
OUT
Power Output. OUT provides bootstrap power to the IC
6
BAT
Battery supply input pin and connection for internal Ring−Killer
7
LX
8
ADEN
9
LBI
Low−Battery Detector Input
10
LBO
Open−Drain Low−Battery Detector Output. Output is Low when VLBI is < 500 mV.
LBO is high impedance shutdown
N−Channel and P−Channel Power MOSFET Drain
Auto Discharge Input
MAXIMUM RATINGS
Rating
Symbol
Value
Unit
VOUT
−0.3, 6.0
V
Input / Output Pins (Pins 1−3,5,7−10)
VIO
−0.3, 6.0
V
Thermal Characteristics
Micro10 Plastic Package, Case 846B, TA = 25°C
Thermal Resistance Junction−to−Air
PD
RqJA
480
250
mW
°C/W
Operating Junction Temperature Range
TJ
− 40 to + 150
°C
Operating Ambient Temperature Range
TA
− 40 to + 85
°C
Storage Temperature Range
Tstg
− 55 to +150
°C
Power Supply (Pin 6)
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
NOTE: ESD data available upon request.
1. This device 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.
TJ(max) * TA
PD +
RqJA
3. Latchup Current Maximum Rating: ±150 mA per JEDEC standard: JESD78.
4. Moisture Sensitivity Level: MSL 1 per IPC/JEDEC standard: J−STD−020A.
5. Measured on approximately 1 in sq of 1 oz Cu.
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2
NCP1423, SCV1423
ELECTRICAL CHARACTERISTICS
(VOUT = 3.3 V, TA = 25°C for typical value, −40°C v TA v 85°C for min/max values unless otherwise noted.)
Characteristic
Operating Voltage
Output Voltage Range
Symbol
Min
Typ
Max
Unit
VIN
0.8
−
VOUT
V
VOUT
1.8
−
3.3
V
VIN_MIN
−
0.85
0.90
V
Reference Voltage
(ILOAD = 0 mA, Cref = 100 nF, TA = 25°C)
VREF
1.177
1.195
1.213
V
Reference Voltage Temperature Coefficient
TCVREF
−
0.05
−
mV/°C
FB Input Threshold (ILOAD = 0 mA, TA = −40°C to 85°C)
VFB
0.489
0.500
0.512
V
FB Input Threshold (ILOAD = 0 mA, TA = 25°C)
VFB
0.493
0.500
0.508
V
FB Input Current
IFB
−
1.0
−
nA
Internal NFET ON−Resistance (ILX=100 mA, TA = 25°C) (Note 7)
RDS(ON)_N
−
0.3
0.45
W
Internal PFET ON−Resistance (ILX=100 mA, TA = 25°C) (Note 7)
RDS(ON)_P
−
0.6
0.8
W
ILIM
−
1.2
−
A
Operating Current into OUT (VFB = 0.7 V, TA = 25°C)
IQ
−
9.0
12
mA
Operating Current into BAT
(VBAT = 1.2 V, VFB = 0.7 V, VLX = 1.2 V, TA = 25°C)
IQBAT
−
2.0
3.0
mA
IBAT_SD
−
0.5
1.5
mA
LX Switch MAX. ON−Time (VFB = 0 V)
tON
1.15
1.4
2.8
ms
LX Switch MIN. OFF−Time (VFB = 0 V)
tOFF
80
200
350
ns
RBAT_LX
−
100
−
W
LBI Input Threshold
VLBI
0.475
0.500
0.525
V
LBI Input Hysteresis
VLBI_HYS
−
15
−
mV
Minimum Input Voltage for Startup
LX Switch Current Limit (NFET) (Note 7)
Shutdown Current into BAT
(LBI/EN = 0 V, VBAT = 3.3 V, TA = 25°C)
BAT to LX Resistance (VFB = 0.7 V)
LBI Input Current
ILBI
−
1.5
−
nA
VLBO_L
−
−
0.2
V
Maximum Continuous Output Current (VIN = 2.5 V, VOUT = 3.3 V) (Note 7)
IOUT
200
−
−
mA
Maximum Continuous Output Current (VIN = 0.8 V, VOUT = 3.3 V) (Note 7)
IOUT
100
−
−
mA
Soft Start Time
(VIN = 1.2 V, TA = 25°C, CREF = 100 nF, VOUT = 3.3 V) (Note 6)
TSS
−
2.0
8.0
ms
VSHDN
0.34
0.50
0.68
V
IEN
−
150
−
nA
LBO Low Output Voltage (VLBI = 0 V, ISINK = 1.0 mA)
EN Shutdown Threshold (VBAT = 1.2 V)
EN Input Current
ADEN Threshold (VBAT = 0.9 V to 3.3 V)
VADEN
ADEN Input Current
IADEN
ADEN Switch Resistance
RADEN
0.5*VBAT
−
100
V
−
100
nA
W
Thermal Shutdown Temperature (Note 7)
TSHDN
−
−
145
°C
Thermal Shutdown Hysteresis (Note 7)
TSDHYS
−
30
−
°C
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
6. Value depends on voltage at VOUT.
7. Values are guaranteed by design.
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3
NCP1423, SCV1423
VBAT
M3
ZLC
EN
1
0.5 V
+
-
Chip
Enable
+
VDD
20 mV
TRUE CUTOFF
CONTROL
CONTROL LOGIC
_ZCUR
_TSDON
LX
7
VOUT
OUT
5
M2
VDD
BAT
6
SENSEFET™
_MSON
_MAINSW2ON
M1
GND
FB
+
-
3
REF
4
GND
_CEN
GND
VDD
_PFM
_MAINSWOFD
PFM
_SYNSW2ON
1.2 V
2
GND
_SYNSWOFD
Voltage
Reference
ADEN
_VREFOK
8
_ILIM
0.5 V
+
-
LBI
9
RSENSE
+
LBO
10
GND
+
-
GND
Figure 2. Detailed Block Diagram
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4
NCP1423, SCV1423
TYPICAL OPERATING CHARACTERISTICS
1.25
CREF = 0.1 mF
VIN = 1.2 V
VOUT = 3.3 V
TA = 25°C
1.25
1.23
VREF, REFERENCE VOLTAGE (V)
VREF, REFERENCE VOLTAGE (V)
1.27
1.21
1.19
1.17
1.15
1
10
100
1.23
1.21
1.19
1.17
1.13
1.5
1000
2
2.5
3
3.5
4
4.5
5
ILOAD, OUTPUT CURRENT (mA)
VOUT, VOLTAGE AT OUT PIN, (V)
Figure 3. Reference Voltage vs. Output Current
Figure 4. Reference Voltage vs. Voltage at OUT Pin
RDS(ON), SWITCH ON RESISTANCE (W)
VREF, REFERENCE VOLTAGE (V)
1.210
1.205
1.200
1.195
1.190
VOUT = 3.3 V
CREF = 0.1 mF
IREF = 0 mA
1.185
1.180
−50
−25
0
25
50
75
100
1.0
VOUT = 3.3 V
0.8
P−FET (M2)
0.6
0.4
N−FET (M1)
0.2
0.0
−40
TA, AMBIENT TEMPERATURE (°C)
0
20
40
60
80
100
Figure 6. Switch ON Resistance vs. Temperature
0.56
IQ, OPERATION CURRENT (mA)
18
0.54
0.52
0.50
0.48
0.46
TA = 25°C
0.44
−50
−20
TA, AMBIENT TEMPERATURE, (°C)
Figure 5. Reference Voltage vs. Temperature
VLBI, LOW BATTERY DETECT VOLTAGE (V)
CREF = 0.1 mF
IREF = 0 mA
TA = 25°C
1.15
−25
0
25
50
75
15
12
9
6
3
0
−50
100
VOUT = 3.3 V
TA, AMBIENT TEMPERATURE (°C)
−25
0
25
50
75
TA, AMBIENT TEMPERATURE (°C)
Figure 7. Low Battery Detect Voltage vs.
Temperature
Figure 8. Operation Current vs. Temperature
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5
100
NCP1423, SCV1423
TYPICAL OPERATING CHARACTERISTICS
5
4
3
2
1
0
−50
IADEN, ADEN PIN INPUT CURRENT (nA)
IBAT_SD, SHUTDOWN CURRENT (mA)
15.0
VOUT = 3.3 V
−25
0
25
50
75
100
10.0
7.5
5.0
2.5
0.0
−50
25
50
75
100
Figure 10. Shutdown Current vs. Temperature
125
100
75
50
−25
0
25
50
75
100
0.53
0.52
0.50
0.49
0.48
0.47
−50
1.6
1.4
1.2
1.0
25
50
75
100
tOFF, LX SWITCH MINIMUM OFF TIME (ms)
VOUT = 3.3 V
0
0
25
50
75
100
Figure 12. Feedback Threshold Voltage vs.
Temperature
2.0
−25
−25
TA, AMBIENT TEMPERATURE (°C)
Figure 11. ADEN Pin Input Current vs.
Temperature
1.8
VOUT = 3.3 V
0.51
TA, AMBIENT TEMPERATURE (°C)
tON, LX SWITCH MAXIMUM ON TIME (ms)
0
Figure 9. LBI Input Current vs. Temperature
150
0.8
−50
−25
TA, AMBIENT TEMPERATURE (°C)
175
25
−50
VOUT = 3.3 V
12.5
TA, AMBIENT TEMPERATURE (°C)
VFB, FEEDBACK THRESHOLD VOLTAGE (V)
ILBI, LBI INPUT CURRENT (nA)
6
0.26
VOUT = 3.3 V
0.24
0.22
0.20
0.18
0.16
0.14
−50
TA, AMBIENT TEMPERATURE (°C)
−25
0
25
50
75
TA, AMBIENT TEMPERATURE (°C)
Figure 13. LX Switch Maximum ON Time vs.
Temperature
Figure 14. LX Switch Minimum OFF Time vs.
Temperature
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100
NCP1423, SCV1423
TYPICAL OPERATING CHARACTERISTICS
250
1.6
VBATT, MINIMUM STARTUP BATTERY
VOLTAGE (V)
IEN, EN PIN INPUT CURRENT (nA)
300
VOUT = 3.3 V
1.4
1.2
200
150
1.0
0.6
50
0
−50
−25
0
25
50
75
0.4
100
OUTPUT VOLTAGE CHANGE (%)
OUTPUT VOLTAGE CHANGE (%)
200
250
6
0
−2
1.5 V
VOUT = 3.3 V, L = 5.6 mH
CIN = 10 mF, COUT = 22 mF
TA = 25°C
1.0 V
10
100
4
2
1.0 V
−2
−4
−6
1
1000
VIN = 1.5 V
0
ILOAD, OUTPUT LOADING CURRENT (mA)
1.2 V
VOUT = 1.8 V, L = 5.6 mH
CIN = 10 mF, COUT = 22 mF
TA = 25°C
10
100
1000
ILOAD, OUTPUT LOADING CURRENT (mA)
Figure 17. Output Voltage Change vs.
Load Current
Figure 18. Output Voltage Change vs.
Load Current
100
100
VIN = 2.5 V
90
EFFICIENCY (%)
90
EFFICIENCY (%)
150
Figure 16. Minimum Startup Battery Voltage vs.
Loading Current
2
2.0 V
80
1.5 V
VIN = 1.2 V
70
50
1
100
Figure 15. EN Input Current vs. Temperature
VIN = 2.5 V
60
50
ILOAD, OUTPUT LOADING CURRENT (mA)
4
−6
1
0
TA, AMBIENT TEMPERATURE (°C)
6
−4
TA = 25°C
VOUT = 3.3 V
L = 5.6 mH
CIN = 10 mF
COUT = 22 mF
VOUT > 0.9 x VSET
0.8
100
VOUT = 3.3 V
CIN = 10 mF, COUT = 22 mF
L = 5.6 mH, TA = 25°C
VIN = 1.2 V, 1.5 V, 2.0 V, 2.5 V
10
VIN = 1.5 V
80
1.0 V
70
1.2 V
60
VOUT = 1.8 V
CIN = 10 mF, COUT = 22 mF
L = 5.6 mH, TA = 25°C
VIN = 1.0 V, 1.2 V, 1.5 V
50
100
40
1000
1
10
100
ILOAD, OUTPUT LOADING CURRENT (mA)
ILOAD, OUTPUT LOADING CURRENT (mA)
Figure 19. Efficiency vs. Load Current
Figure 20. Efficiency vs. Load Current
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1000
NCP1423, SCV1423
250
VOUT = 3.3 V, L = 5.6 mH
CIN = 10 mF, COUT = 22 mF
TA = 25°C
200
IBATT, NO LOAD OPERATING CURRENT (mA)
VRIPPLE, OUTPUT RIPPLE VOLTAGE (mVp−p)
TYPICAL OPERATING CHARACTERISTICS
50 mA
150
100 mA
100
50
0
1.3
1.5
1.7
1.9
2.1
2.3
2.5
VBATT, BATTERY INPUT VOLTAGE (V)
15
12.5
10
7.5
5.0
2.5
1.8
L = 5.6 mH, CIN = 10 mF,
COUT = 22 mF, TA = 25°C
2.1
2.4
2.7
3.0
3.3
VOUT, INPUT VOLTAGE AT OUT PIN (V)
Figure 22. No Load Operating Current vs. Input
Voltage at OUT Pin
Figure 21. Output Ripple Voltage vs. Battery Input
Voltage
Upper Trace: Output Voltage Waveform, 2.0 V/Division
Middle Trace: Input Voltage Waveform, 1.0 V/Division
Lower Trace: Inductor Current Waveform, 500 mA/Division
Upper Trace: Voltage at LBI Pin, 0.5 V/Division
Lower Trace: Voltage at LBO Pin, 1.0 V/Division
(VIN = 1.8 V, VOUT = 3.3 V, L = 5.6 mH, ILOAD = 60 mA)
Figure 23. Low Battery Detect
Figure 24. Startup Transient Response
Upper Trace: Output Voltage Ripple, 100 mV/Division
Middle Trace: Voltage at Lx pin, 2.0 V/Division
Lower Trace: Inductor Current, 500 mA/Division
(VIN = 1.5 V, VOUT = 3.3 V, ILOAD = 50 mA; L = 5.6 mH, COUT = 22 mF)
Upper Trace: Output Voltage Ripple, 100 mV/Division
Middle Trace: Voltage at LX pin, 2.0 V/Division
Lower Trace: Inductor Current, 500 mA/Division
(VIN = 1.5 V, VOUT = 3.3 V, ILOAD = 200 mA; L = 5.6 mH, COUT = 22 mF)
Figure 25. Discontinuous Conduction Mode
Switching Waveform
Figure 26. Continuous Conduction Mode
Switching Waveform
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8
NCP1423, SCV1423
TYPICAL OPERATING CHARACTERISTICS
Upper Trace: Output Voltage Ripple, 50 mV/Division
Lower Trace: Battery Voltage, VIN, 1.0 V/Division
(VIN = 1.2 V to 2.0 V; L = 5.6 mH, COUT = 22 mF, ILOAD = 50 mA)
Upper Trace: Output Voltage Ripple, 50 mV/Division
Lower Trace: Battery Voltage, VIN, 1.0 V/Division
(VIN = 1.0 V to 1.6 V; L = 5.6 mH, COUT = 22mF, ILOAD = 50 mA)
Figure 27. Line Transient Response for VOUT = 3.3 V
Figure 28. Line Transient Response For VOUT = 1.8 V
Upper Trace: Output Voltage Ripple, 100 mV/Division
Lower Trace: Load Current, ILOAD, 100 mA/Division
(VOUT = 3.3 V, ILOAD = 10 mA to 200 mA; L = 5.6 mH, COUT = 22 mF)
Upper Trace: Output Voltage Ripple, 100 mV/Division
Lower Trace: Load Current, ILOAD, 100 mA/Division
(VOUT = 1.8 V, ILOAD = 10 mA to 100 mA; L = 5.6 mH, COUT = 22 mF)
Figure 29. Load Transient Response For VIN = 1.5 V
Figure 30. Load Transient Response For VIN = 1.0 V
Upper Trace: Output Voltage, 2.0 V/Division
Lower Trace: Output Current, 50 mA/Division
Middle Trace: Enable Pin Waveform, 1.0 V/Division
(VIN = 1.5 V, VOUT = 3.3 V, L = 5.6 mH, CIN = 10 mF, COUT = 22 mF)
Upper Trace: Output Voltage, 2.0 V/Division
Lower Trace: Output Current, 50 mA/Division
Middle Trace: Enable Pin Waveform, 1.0 V/Division
(VIN = 1.5 V, VOUT = 3.3 V, L = 5.6 mH, CIN = 10 mF, COUT = 22 mF)
Figure 31. Startup Waveform (ADEN Disabled)
Figure 32. Startup Waveform (ADEN Enabled)
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NCP1423, SCV1423
DETAILED OPERATION DESCRIPTION
introduced to make sure M1 is completely turned OFF
before M2 is being turned ON.
The previously mentioned situation occurs when the
regulator is operating in CCM, M2 is being turned OFF, M1
is just turned ON, and M2 is not being completely turned
OFF, A dead time is also needed to make sure M2 is
completely turned OFF before M1 is being turned ON.
As coil current is dropped to zero when the regulator is
operating in DCM, M2 should be OFF. If this does not occur,
the reverse current flows from the output bulk capacitor
through M2 and the inductor to the battery input, causing
damage to the battery. The ZLC comparator comes with
fixed offset voltage to switch M2 OFF before any reverse
current builds up. However, if M2 switch OFF too early,
large residue coil current flows through the body diode of
M2 and increases conduction loss. Therefore, determination
on the offset voltage is essential for optimum performance.
With the implementation of synchronous rectification
scheme, efficiency can be as high as 90% with this device.
NCP1423 is a monolithic micropower high−frequency
step−up voltage switching converter IC specially designed
for battery operated hand−held electronic products up to
200 mA loading. It integrates a Synchronous Rectifier to
improving efficiency as well as to eliminate the external
Schottky diode. High switching frequency (up to 600 kHz)
allows for a low profile inductor and output capacitor to be
used. Low−Battery Detector, Logic−Controlled Shutdown
and Cycle−by−Cycle Current Limit provide value−added
features for various battery−operated applications. With all
these functions ON, the quiescent supply current is typical
only 9 mA typical. This device is available in compact
Micro10 package.
PFM Regulation Scheme
From the detailed block diagram (Figure 2), the output
voltage is divided down and fed back to Pin 3 (FB). This
voltage goes to the non−inverting input of the PFM
comparator whereas the comparator’s inverting input is
connected to the internal voltage reference, REF. A
switching cycle is initiated by the falling edge of the
comparator, at the moment the main switch (M1) is turned
ON. After the maximum ON−time (typical 1.4 mS) elapses
or the current limit is reached, M1 is turned OFF, and the
synchronous switch (M2) is turned ON. The M1 OFF time
is not less than the minimum OFF−time (typically 0.20 mS),
which ensure complete energy transfer from the inductor to
the output capacitor. If the regulator is operating in
continuous conduction mode (CCM), M2 is turned OFF just
before M1 is supposed to be ON again. If the regulator is
operating in discontinuous conduction mode (DCM), which
means the coil current will decrease to zero before the new
cycle start, M1 is turned OFF as the coil current is almost
reaching zero. The comparator (ZLC) with fixed offset is
dedicated to sense the voltage drop across M2 as it is
conducting, when the voltage drop is below the offset, the
ZLC comparator output goes HIGH, and M2 is turned OFF.
Negative feedback of closed loop operation regulates
voltage at Pin 3 (FB) equal to the internal divide down
reference voltage times (0.5 V).
Cycle−by−Cycle Current Limit
In Figure 2, SENSEFET is used to sample the coil current
as M1 is ON. With that sample current flowing through a
sense resistor, a sense−voltage is developed. Threshold
detector (ILIM) detects whether the sense−voltage is higher
than the preset level. If the sense voltage is higher than the
present level, the detector output notifies the Control Logic
to switch OFF M1, and M1 can only be switched ON when
the next cycle starts after the minimum OFF−time (typically
0.20 mS). With proper sizing of SENSEFET and sense
resistor, the peak coil current limit is typically set at 1.2 A.
Voltage Reference
The voltage at REF is typically set at 1.2 V and can output
up to 2.5 mA with load regulation ±2.0%, at VOUT equal to
3.3 V. If VOUT is increased, the REF load capability can also
be increased. A bypass capacitor of 200 nF is required for
proper operation when REF is not loaded. If REF is loaded,
1.0 mF capacitor at REF pin is needed.
True−Cutoff
The NCP1423 has a True−Cutoff function controlled by
the EN pin (Pin 1). Internal circuitry can isolate the current
through the body diode of switch M2 to load. Thus, it can
eliminate leakage current from the battery to load in
shutdown mode and significantly reduces battery current
consumption during shutdown. The shutdown function is
controlled by the voltage at Pin 1 (EN). When Pin 1 is pulled
to lower than 0.5 V, the controller enters shutdown mode. In
shutdown mode, when the switches M1 and M2 are both
switched OFF, the internal reference voltage of the
controller is disable and the controller typically consumes
only 600 nA of current. If the Pin 1 voltage is raised to higher
than 0.5 V, for example, by a resistor connected to VIN, the
Synchronous Rectification
The Synchronous Rectifier is used to replace the Schottky
Diode to reduce the conduction loss contributed by the
forward voltage of the Schottky Diode. The Synchronous
Rectifier is normally realized by PowerFET with gate
control circuitry that incorporates relatively complicated
timing concerns.
As the main switch (M1) is being turned OFF and the
synchronous switch M2 is just turned ON with M1 not being
completely turned OFF, current is shunt from the output bulk
capacitor through M2 and M1 to ground. This power loss
lowers overall efficiency and possibly damage the switching
FETs. As a general practice, certain amount of dead time is
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10
NCP1423, SCV1423
IC is enabled again, and the internal circuit typically
consumes 9 mA of current from the OUT pin during normal
operation.
comparator output turns off the 50 W low side switch. When
this occurs, Pin 10 becomes high impedance and its voltage
is pulled high again.
Low−Battery Detection
Auto Discharge
A comparator with 15 mV hysteresis is applied to perform
the low−battery detection function. When Pin 9 (LBI) is at
a voltage (defined by a resistor divider from the battery
voltage) lower than the internal reference voltage of 0.5 V,
the comparator output turns on a 50 W low side switch. It
pulls down the voltage at Pin 10 (LBO) which requires a
hundred to a thousand kW of external pull−high resistance.
If the Pin 9 voltage is higher than 0.5 V+15 mV, the
Auto discharge function is using for ensure the output
voltage status after the power down occur. This function is
using for communication with a digital signal. When auto
discharge function is enabled, the ADEN is set high; the
output capacitor will be discharged after the device is
shutdown. The capacitors connected to the output are
discharged by an integrated switch of 100 W. The residual
voltage on VOUT will be less than 0.4 V after auto discharge.
APPLICATIONS INFORMATION
Output Voltage Setting
Capacitors Selection
A typical application circuit is shown in Figure 1, The
output voltage of the converter is determined by the external
feedback network comprised of R1 and R2 and the
relationship is given by:
In all switching mode boost converter applications, both
the input and output terminals see impulsive voltage /
current waveforms. The currents flowing into and out of the
capacitors multiply with the Equivalent Series Resistance
(ESR) of the capacitor to produce ripple voltage at the
terminals. During the Syn−Rect switch−off cycle, the
charges stored in the output capacitor are used to sustain the
output load current. Load current at this period and the ESR
combined and reflect as ripple at the output terminals. For all
cases, the lower the capacitor ESR, the lower the ripple
voltage at output. As a general guideline, low ESR
capacitors should be used.
VOUT + 0.5 V
ǒ1 ) R1
Ǔ
R2
where R1 and R2 are the upper and lower feedback resistors,
respectively.
Low Battery Detect Level Setting
The Low Battery Detect Voltage of the converter is
determined by the external divider network comprised of R3
and R4 and the relationship is given by:
VLBI + 0.5 V
PCB Layout Recommendations
ǒ1 ) R3
Ǔ
R4
Good PCB layout plays an important role in switching
mode power conversion. Careful PCB layout can help to
minimize ground bounce, EMI noise, and unwanted
feedback that can affect the performance of the converter.
Hints suggested below can be used as a guideline in most
situations.
where R3 and R4 are the upper and lower divider resistors
respectively.
Inductor Selection
The NCP1423 is tested to produce optimum performance
with a 5.6 mH inductor at VIN = 1.3 V, VOUT = 3.3 V,
supplying an output current up to 200 mA. For other input
/ output requirements, inductance in the range 3 mH to 10 mH
can be used according to end application specifications.
Selecting an inductor is a compromise between output
current capability, inductor saturation limit and tolerable
output voltage ripple. Low inductance values can supply
higher output current but also increase the ripple at output
and decrease efficiency. On the other hand, high inductance
values can improve output ripple and efficiency; however,
it also limited the output current capability at the same time.
Another parameter of the inductor is its DC resistance.
This resistance can introduce unwanted power loss and
reduce overall efficiency. The basic rule is to select an
inductor with lowest DC resistance within the board space
limitation of the end application.
Grounding
A star−ground connection should be used to connect the
output power return ground, the input power return ground,
and the device power ground together at one point. All
high−current paths must be as short as possible and thick
enough to allow current to flow through and produce
insignificant voltage drop along the path. The feedback
signal path must be separated from the main current path and
sense directly at the anode of the output capacitor.
Components Placement
Power components (i.e. input capacitor, inductor and
output capacitor) must be placed as close together as
possible. All connecting traces must be short, direct and
thick. High current flowing and switching paths must be
kept away from the feedback (FB, Pin 3) terminal to avoid
unwanted injection of noise into the feedback path.
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11
NCP1423, SCV1423
LAYOUT GUIDELINES
Figure 33. Layout Guidelines
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12
NCP1423, SCV1423
General Design Procedures
Assume the efficiency h = 85%
Determine the peak inductor ripple current, IRIPPLE−P and
calculate the inductor value:
Assume IRIPPLE−P is 40% of ILAVG, the inductance of the
power inductor can be calculated as in below:
Switching mode converter design is important. Suitable
choice an inductor and capacitor value can make the
converter has an optimum performance. Below a simple
method base on the most basic first order equations to
estimate the inductor and capacitor values for NCP1423
operate in Continuous Conduction Mode (CCM) is
introduced. The component value set can be used as a
starting point to fine−tune the circuit operation. By all
means, detail bench testing is needed to get the best
performance out of the circuit.
IRIPPLE−P = 0.40 x 381 mA / h = 179 mA
L+
A standard value of 5.6 mH is selected for initial trial.
Determine the output voltage ripple, VOUT−RIPPLE and
calculate the output capacitor value:
VOUT−RIPPLE = 30 mVP−P at IOUT = 150 mA
Design Parameters:
For one cells supply application
VIN = 1.1 V to 1.5 V, Typical 1.3 V
VOUT = 3.3 V
IOUT = 150 mA (200 mA max)
VLB = 1.0 V
VOUT−RIPPLE = 30 mVp−p at IOUT = 150 mA
Calculate the feedback network:
Select R2 = 100 k
R1 + R2
COUT u
V
ǒ3.3
* 1Ǔ + 560 k
0.5 V
Calculate the Low Battery Detect divider:
VLB0 = 1.0 V
Select R4 = 100 k
R3 + R4
ESRCOUT
Feedforward Capacitor (C1) Selection
A feedforward capacitor might be required to be added in
parallel to the upper feedback resistor to avoid double
pulsing or group pulsing at the switching node which causes
larger inductor ripple current and higher output voltage
ripple. With adequate feedforward capacitor, evenly
distributed single pulses at the switching node can be
achieved. For NCP1423, the lower the switching frequency
is, the larger the feedforward capacitor value should be. For
initial trial value, the following equation can be used, but
actual value may need fine tuning:
ǒVVLB0
* 1Ǔ
LB1
R3 + 100 k
IOUT tON
VOUT*RIPPLE * IOUT
where tON = 1.4 mS and ESRCOUT = 0.1 W,
From above calculation, you need at least 14 mF in order
to achieve the specified ripple level at conditions stated.
Practically, a one level larger capacitor will be used to
accommodate factors not taken into account in the
calculations. Therefore, a capacitor value of 22 mF is
selected. The NCP1423 is internal compensated for most
applications. But in case additional compensation is
required, the capacitor C1 can be used as external
compensation adjustment to improve system dynamics.
ǒVVOUT
* 1Ǔ
FB
R1 + 100 k
1.3 V 1.4 mS
VIN tON
+
+ 5.0 mH
2 IRIPPLE*P
2 (179 mA)
V
ǒ1.0
* 1Ǔ + 100 k
0.5 V
Determine the steady state duty ratio, D for typical VIN,
operation will be optimized around this point:
VOUT
+ 1
1*D
VIN
C FF [
1.3 V
V
D + 1 * IN + 1 *
+ 0.606
VOUT
3.3 V
1
2
p
F
SW
20
R1
FSW is the switching frequency measured for nominal
load. If a feedforward capacitor is used, the equation
provides an initial starting value. Some trimming of the
feedback capacitor may be required depending on the
desired output value.
Determine the average inductor current, ILAVG at
maximum IOUT:
150 mA
I
ILAVG + OUT +
+ 381 mA
1 * 0.606
1*D
SENSEFET is a trademark of Semiconductor Components Industries, LLC.
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13
MECHANICAL CASE OUTLINE
PACKAGE DIMENSIONS
Micro10
CASE 846B−03
ISSUE D
DATE 07 DEC 2004
SCALE 2:1
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION “A” DOES NOT INCLUDE MOLD
FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE
BURRS SHALL NOT EXCEED 0.15 (0.006)
PER SIDE.
4. DIMENSION “B” DOES NOT INCLUDE
INTERLEAD FLASH OR PROTRUSION.
INTERLEAD FLASH OR PROTRUSION
SHALL NOT EXCEED 0.25 (0.010) PER SIDE.
5. 846B−01 OBSOLETE. NEW STANDARD
846B−02
−A−
−B−
K
D 8 PL
0.08 (0.003)
PIN 1 ID
G
0.038 (0.0015)
−T−
M
T B
S
A
C
SEATING
PLANE
H
MILLIMETERS
MIN
MAX
2.90
3.10
2.90
3.10
0.95
1.10
0.20
0.30
0.50 BSC
0.05
0.15
0.10
0.21
4.75
5.05
0.40
0.70
DIM
A
B
C
D
G
H
J
K
L
S
L
J
GENERIC
MARKING DIAGRAM*
SOLDERING FOOTPRINT
10X
1.04
0.041
0.32
0.0126
3.20
0.126
8X
xxxx
AYW
10X
4.24
0.167
0.50
0.0196
INCHES
MIN
MAX
0.114
0.122
0.114
0.122
0.037
0.043
0.008
0.012
0.020 BSC
0.002
0.006
0.004
0.008
0.187
0.199
0.016
0.028
SCALE 8:1
5.28
0.208
xxxx
A
Y
W
= Device Code
= Assembly Location
= Year
= Work Week
= Pb−Free Package
*This information is generic. Please refer to
device data sheet for actual part marking.
Pb−Free indicator, “G” or microdot “ ”,
may or may not be present.
mm
inches
Micro10
DOCUMENT NUMBER:
98AON03799D
Electronic versions are uncontrolled except when
accessed directly from the Document Repository. Printed
STATUS: ON SEMICONDUCTOR STANDARD
versions are uncontrolled except when stamped
“CONTROLLED COPY” in red.
NEW STANDARD:
Semiconductor Components Industries, LLC, 2002
Case Outline Number:
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Micro10
DESCRIPTION:
October, 2002
− Rev. 0
PAGE 1 OFXXX
2
1
DOCUMENT NUMBER:
98AON03799D
PAGE 2 OF 2
ISSUE
REVISION
DATE
O
RELEASED FOR PRODUCTION. REQ BY J. HOSKINS.
09 NOV 2000
A
DIM “D” WAS 0.25−0.4MM/0.10−0.016IN. ADDED NOTE 5.
USED ON: WAS 10 LEAD TSSOP, PITCH 0.65 REQ BY J. HOSKINS.
13 NOV 2000
B
CHANGED “USED ON” WAS: 10 LEAD TSSOP, PITCH 0.50MM. REQ BY A. HAMID.
11 JUL 2001
C
CHANGED “D” DIMENSION MAX FROM 0.35 TO 0.30MM AND 0.014 TO 0.012IN.
REQ BY D. TRUHITTE.
31 JUL 2003
D
ADDED FOOTPRINT INFORMATION. REQ. BY K. OPPEN.
07 DEC 2004
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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
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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.
Semiconductor Components Industries, LLC, 2004
December, 2004 − Rev. 03D
Case Outline Number:
846B
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