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PDF NCP1530DM30R2G Data sheet ( Hoja de datos )
| Número de pieza | NCP1530DM30R2G | |
| Descripción | 600 mA PWM/PFM Step-Down Converter with External Synchronization Pin | |
| Fabricantes | ON | |
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NCP1530
600 mA PWM/PFM
Step−Down Converter with
External Synchronization Pin
The NCP1530 is a PWM/PFM non−synchronous step−down
(Buck) DC−DC converter for usage in systems supplied from 1−cell
Li−ion, or 2 or more cells Alkaline/NiCd/NiMH batteries. It can
operate in Constant−Frequency PWM mode or PWM/PFM mode in
which the controller will automatically switch to PFM mode
operation at low output loads to maintain high efficiency. The
switching frequency can also be synchronized to external clock
between 600 kHz and 1.2 MHz. The maximum output current is up
to 600 mA. Applying an external synchronizing signal to SYN pin
can supersede the PFM operation.
The NCP1530 consumes only 47 mA (typ) of supply current
(VOUT = 3.0 V, no switching) and can be forced to shutdown mode by
bringing the enable input (EN) low. In shutdown mode, the regulator
is disabled and the shutdown supply current is reduced to
0.5 mA (typ). Other features include built−in undervoltage lockout,
internal thermal shutdown, an externally programmable soft−start
time and output current limit protection. The NCP1530 operates
from a maximum input voltage of 5.0 V and is available in a space
saving, low profile Micro8™ package.
Features
• Pb−Free Package is Available
• High Conversion Efficiency, up to 92% at VIN = 4.3 V,
VOUT = 3.3 V, IOUT = 300 mA
• Current−Mode PWM Control
• Automatic PWM/PFM Mode for Current Saving at Low Output Loads
• Internal Switching Transistor Support 600 mA Output Current
(VIN = 5.0 V, VOUT = 3.3 V)
• High Switching Frequency (600 kHz), Support Small Size Inductor
and Capacitor, Ceramic Capacitors Can be Used
• Synchronize to External Clock Signal up to 1.2 MHz
• 100% Duty Cycle for Maximum Utilization of the Supply Source
• Programmable Soft−Start Time through External Chip Capacitor
• Externally Accessible Voltage Reference
• Built−In Input Undervoltage Lockout
• Built−In Output Overvoltage Protection
• Power Saving Shutdown Mode
• Space Saving, Low Profile Micro8 Package
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8
1
MARKING
DIAGRAM
Micro8]
DM SUFFIX
CASE 846A
xxxx
ALYW
xxxx = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
PIN CONNECTIONS
VIN
SYN
SS
GND
1
2
3
4
(Top View)
8 LX
7 VREF
6 VOUT
5 EN
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 14 of this data sheet.
Typical Applications
• PDAs
• Digital Still Camera
• Cellular Phone and Radios
• Portable Test Equipment
• Portable Scanners
• Portable Audio Systems
© Semiconductor Components Industries, LLC, 2004
November, 2004 − Rev. 3
1
Publication Order Number:
NCP1530/D
1 page  
NCP1530
TYPICAL OPERATING CHARACTERISTICS (VIN = VR + 1.0 V, test circuit, refer to Figure 1, CSS = NC and CVREF = 1.0 mF, TA =
25°C for typical value, 0°C ≤ TA ≤ 85°C for min/max values unless otherwise noted.) *VR is the factory−programmed output voltage setting.
2.60
2.55
2.50
VIN = 3.5 V
ILoad = 150 mA
2.80
2.75
2.70
VIN = 3.7 V
ILoad = 150 mA
2.45
VIN = 5.0 V
2.65
VIN = 5.0 V
2.40
0
17 34 51 68
TA, AMBIENT TEMPERATURE (°C)
85
Figure 3. Output Voltage vs. Ambient Temperature
(VOUT = 2.5 V)
3.10
3.05
ILoad = 150 mA
3.00
VIN = 4.0 V
2.95
VIN = 5.0 V
2.60
0
17 34 51 68
TA, AMBIENT TEMPERATURE (°C)
85
Figure 4. Output Voltage vs. Ambient Temperature
(VOUT = 2.7 V)
3.40
3.35
ILoad = 150 mA
3.30
VIN = 4.3 V
3.25
VIN = 5.0 V
2.90
0
17 34
51 68 85
TA, AMBIENT TEMPERATURE (°C)
Figure 5. Output Voltage vs. Ambient Temperature
(VOUT = 3.0 V)
3.20
0
17 34
51 68 85
TA, AMBIENT TEMPERATURE (°C)
Figure 6. Output Voltage vs. Ambient Temperature
(VOUT = 3.3 V)
90
VIN = VR + 1.0 V
ILoad = 0 mA
75
500
VIN = 5.0 V
400 ILoad = 0 mA
60
3.3 V
33.0.0VV
45
30
0
2.5 V 2.7 V
17 34 51 68
TA, AMBIENT TEMPERATURE (°C)
85
Figure 7. Supply Current vs. Ambient Temperature
300
3.3 V
200
100
2.5 V
0
0 17 34 51 68 85
TA, AMBIENT TEMPERATURE (°C)
Figure 8. Shutdown Current vs. Ambient Temperature
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5
5 Page 
NCP1530
DETAILED OPERATING DESCRIPTION
Introduction
The NCP1530 series are step−down converters with a
smart control scheme that operates with 600 kHz fixed
Pulse Width Modulation (PWM) at moderate to heavy load
currents, so that high efficiency, noise free output voltage
can be generated. In order to improve the system efficiency
at light loads, this device can be configured to work in
auto−mode. In auto−mode operation, the control unit will
detect the loading condition and switch to power saving
Pulse Frequency Modulation (PFM) control scheme at
light load. With these enhanced features, the converter can
achieve high operating efficiency for all loading
conditions. Additionally, the switching frequency can also
be synchronized to external clock signal in between
600 kHz to 1.2 MHz range. The converter uses peak
current mode PWM control as a core, with the high
switching frequency incorporated. Good line and load
regulation can be achieved easily with small value ceramic
input and output capacitors. Internal integrated
compensation voltage ramp ensures stable operation at all
operating modes. NCP1530 series are designed to support
up to 600 mA output current with cycle−by−cycle current
limit protection.
The Internal Oscillator
The oscillator that governs the switching of the PWM
control cycle is self contained and no external timing
component is required to setup the switching frequency.
For PWM mode and auto−mode operation, all timing
signals required for proper operation are derived from the
internal oscillator. The internal fix frequency oscillator is
trimmed to run at 600 kHz " 20% over full temperature
range. In case the device is forced to operate at
Synchronization mode by applying an external clock signal
to SYN pin (pin 2), the external clock signal will supersede
the internal oscillator and take charge of the switching
operation.
Voltage Reference and Soft−Start
An internal high accuracy voltage reference is included
in NCP1530. This reference voltage governs all internal
reference levels in various functional blocks required for
proper operation. This reference voltage is precisely
trimmed to 1.2 V " 1.5% over full temperature range. The
reference voltage can be accessed externally at VREF pin
(pin 7), with an external capacitor, CREF of 1.0 mF, privding
up to 5.0 mA of loading. Additionally, NCP1530 has a
Soft−Start circuit built around the voltage reference block
that provide limits to the inrush current during start−up by
controlling the ramp up of the internal voltage reference.
The soft−start time can be user adjusted by an external
capacitor, CSS, connecting to the SS pin (pin 3). During
converter powerup, a 50 nA current flowing out from the
SS pin will charge−up the timing capacitor. The voltage
across the SS pin controls the ramp up of the internal
reference voltage by slowly releasing it until the nominal
value is reached. For an external timing capacitor of value
CSS = 100 pF, the soft−start time is about 5.0 ms including
the small logic delay time, Figure 33 and 34. In the case
where the SS pin is left floating, a small built−in capacitor
together with other parasitic capacitance will provide a
minimum intrinsic soft−start time of 500 ms. As the
soft−start function is implemented by simple circuitry, the
final timing depends on non−linear functions, where
accurate deterination of the soft−start timing is impossible.
However, for simplicity, the empirical formula below can
be used to estimate the soft−start time with respect to the
value of the external capacitor.
tSS in ms [ 50 CSS in pF ) 500 ms
Current Mode Pulse−Width Modulation (PWM)
Control Scheme
With the SYN pin (pin 2) connected to VIN, the converter
will set to operate at constant switching frequency PWM
mode. NCP1530 uses peak current mode control scheme to
achieve good line and load regulation. The high switching
frequency, 600 kHz, and a carefully compensated internal
control loop, allows the use of low profile small value
ceramic type input and output capacitor for stable
operation. In current mode operation, the required ramp
function is generated by sensing the inductor current
(ISEN) and comparing with the voltage loop error
amplifier (OTA) output. The OTA output is derived from
feedback from the output voltage pin (VOUT − Pin 6) and
the internal reference voltage (VREF − Pin 7). See Figure 2.
On a cycle−by−cycle basis, the duty cycle is controlled to
keep the output voltage within regulation. The current
mode approach has outstanding line regulation
performance and good overall system stability.
Additionally, by monitoring the inductor current, a
cycle−by−cycle current limit protection is implemented.
Constant Frequency PWM scheme reduces output ripple
and noise, which is one of the important characteristics for
noise sensitive communication applications. The high
switching frequency allows the use of small size surface
mount components that saves significant PC board area and
improves layout compactness and EMI performance.
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11
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| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet NCP1530DM30R2G.PDF ] | |
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