Semiconductor Components Industries, LLC, 2004

March, 2004 - Rev. 7

Publication Order Number:

NCP1501/D

NCP1501

Dual Mode PWM/Linear
Buck Converter

The NCP1501 is a dual mode regulator that operates either as a

PWM Buck Converter or as a Low Drop Out Linear Regulator. If a
synchronization signal is present, the NCP1501 operates as a current
mode PWM converter with synchronous rectification. The
synchronization signal allows the user to control the location of the
spurious frequency noise generated by a PWM converter. Linear mode
is active when a synchronization signal is not present. The NCP1501
configuration allows an efficient high power operation and low noise
during system sleep modes.

Features

Synchronous Rectification for Higher Efficiency in PWM Mode

Linear Mode Operation for Low Noise Output at Low Loads

Integrated MOSFETs and Feedback Circuits

Cycle-by-Cycle Peak Current Limit of 800 mA (typ)

Automatic Switching Between PWM and Linear Mode

Operating Frequency Range of 500 to 1000 kHz

Optimized for Ceramic Capacitors and Low Profile Inductors

Thermal Limit Protection

Built-in Slope Compensation for Current Mode PWM Converter

Fixed Output Voltages of 1.05 V, 1.35 V, 1.57 V, 1.8 V

Shutdown Current Consumption of 0.2

Internal Soft Start

Transistor Count: 3500

Pb-Free Package is Available

Typical Applications

Cellular Phones

PDAs

Pagers

Supplies for DSP Cores

Portable Applications

Figure 1. Typical Applications Circuit

OUT

NCP1501

SHD

SYN

CB0

CB1

GND

bat

out

Micro8

(MSOP-8)

DM SUFFIX
CASE 846A

1501= Device Code
A

= Assembly Location

= Year

= Work Week

MARKING
DIAGRAM

PIN CONNECTIONS

SHD

SYN

CB0

CB1

GND

Device

Package

Shipping

ORDERING INFORMATION

NCP1501DMR2

Micro8

4000/Tape & Reel

(Top View)

1501
AYW

http://onsemi.com

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.

NCP1501DMR2G

Micro8

(Pb-Free)

4000/Tape & Reel

NCP1501

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PIN FUNCTION DESCRIPTIONS

Pin #

Symbol

Pin Description

SHD

Enable Pin for the NCP1501. This pin is active high. Internal pull down resistor forces the part off if the pin is
not connected on the board.

SYN

External Synchronization Signal Pin. The device will operate in PWM mode if a clock signal is present. The
pin must be pulled low to enter LDO mode. Internal pull down resistor on pin.

Feedback for the NCP1501. An internal MOSFET is connected across V

and LX for LDO mode.

Connection for the pass devices to the inductor.

Input voltage to the NCP1501.

GND

Ground Connection for the device.

CB1

Voltage Selection Bit. Internal pull up resistor on pin.

CB0

Voltage Selection Bit. Internal pull down resistor on pin.

MAXIMUM RATINGS

Rating

Symbol

Value

Unit

Maximum Voltage All Pins

max

5.5

Maximum operating Voltage All Pins

max

5.2

Thermal Resistance, Junction-to-Air

240

C/W

Operating Ambient Temperature Range

-30 to +85

ESD Withstand Voltage

Human Body Model (Note 1)

Machine Model (Note 2)

ESD

> 2500

> 100

Moisture Sensitivity

MSL

Level 1

Storage Temperature Range

stg

-55 to +150

Junction Operating Temperature Range

-30 to +125

Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit
values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied,
damage may occur and reliability may be affected.
1. Tested to EIA/JESD22-A114-A
2. Tested to EIA/JESD22-A115-A

ELECTRICAL CHARACTERISTICS (V

= 3.6 V, V

= 1.57 V, T

= 25

C, F

syn

= 600 kHz 50% Duty Cycle square wave for PWM mode;

= -30 to 85

C for Min/Max values, unless otherwise noted.)

Characteristic

Symbol

Min

Typ

Max

Unit

Pin

Quiescent Current of Switching Mode, I

out

= 0 mA

Iq PWM

124

500

Quiescent Current of LDO Mode, I

out

= 0 mA

Iq LDO

Quiescent Current, SHD Low

Iq Off

0.2

1.0

Input Voltage Range

2.7

5.2

Sync Pin

Input Voltage

sync

-0.3

+0.3

Frequency Operational Range

sync

500

1000

kHz

Minimum Synchronization Pulse Width

sync(min)

Maximum Synchronization Pulse Width

sync(max)

SYNC "H" Voltage Threshold

sync(H)

920

1200

SYNC "L" Voltage Threshold

sync(L)

400

830

SYNC "H" Input Current, V

sync

= 3.6 V

sync(H)

1.8

SYNC "L" Input Current, V

sync

= 0 V

sync(L)

-0.5

0.005

NCP1501

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ELECTRICAL CHARACTERISTICS (continued) (V

= 3.6 V, V

= 1.57 V, T

= 25

C, F

syn

= 600 kHz 50% Duty Cycle square wave for

PWM mode; T

= -30 to 85

C for Min/Max values, unless otherwise noted.)

Characteristic

Symbol

Min

Typ

Max

Unit

Output Level Selection Pins

Input Voltage

-0.3

+0.3

CB0,1 "H" Voltage Threshold

CB(H)

910

1200

CB0,1 "L" Voltage Threshold

CB(L)

400

850

CB0,1 "H" Input Current, CBx = 3.6 V

CB(H)

1.8

CB0,1 "L" Input Current, CBx = 0 V

CB(L)

-0.5

Shutdown Pin

Input Voltage

SHD

-0.3

+0.3

SHD "H" Voltage Threshold

SHD(H)

920

1200

SHD "L" Voltage Threshold

SHD(L)

400

850

SHD "H" Input Current, SHD = 3.6 V

SHD(H)

1.8

SHD "L" Input Current, SHD = 0 V

SHD(L)

-0.5

Feedback Pin

Input Voltage

-0.3

+0.3

Input Current, V

= 1.8 V

8.5

PWM Mode Characteristics

Switching P-FET Current Limit

lim

800

Duty Cycle

100

Minimum On Time

on(min)

100

nsec

DS(on)

Switching

N-FET
P-FET

DS(on)

-
-

0.7
0.6

-
-

Ohms

Switching P-FET and N-FET Leakage Current

leak

0.01

Output Over Voltage Threshold

3.0

Output Voltage Accuracy, Vout

(set)

= 1.05 V CB0 = L, CB1 = L

Output Voltage Accuracy,

Vout

(set)

= 1.35 V CB0 = L, CB1 = H

Output Voltage Accuracy,

Vout

(set)

= 1.57 V CB0 = H, CB1 = H

Output Voltage Accuracy,

Vout

(set)

= 1.80 V CB0 = H CB1 = L

out

1.018
1.309
1.523
1.740

1.050
1.350
1.570
1.800

1.082
1.391
1.617
1.860

Load Transient Response, 10 to 100 mA Load Step

out

Line Transient Response, I

out

= 100 mA, 3.0 to 3.6 V

Line Step

out

LDO Mode Characteristics

DS(on)

LDO FET (Inductor Switch), LX to V

out

DS(on)

7.0

Ohms

Dropout Voltage (Limited by V

in(min)

= 2.5 V and V

out(max)

= 1.8 V)

- V

out

0.7

Output Voltage Accuracy, Vout

(set)

= 1.05 V CB0 = L, CB1 = L

Output Voltage Accuracy,

Vout

(set)

= 1.35 V CB0 = L, CB1 = H

Output Voltage Accuracy,

Vout

(set)

= 1.57 V CB0 = H, CB1 = H

Output Voltage Accuracy,

Vout

(set)

= 1.80 V CB0 = H CB1 = L

out

1.018
1.309
1.523
1.740

1.050
1.350
1.570
1.800

1.082
1.391
1.617
1.860

Thermal Shutdown

Thermal Shutdown

TSD

160

Hysteresis

TSD

hys

NCP1501

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DETAILED OPERATING DESCRIPTION

The Buck regulator is a synchronous rectifier PWM

regulator with integrated MOSFETs. This regulator has an
LDO function for low power modes to conserve power and
lower ripple voltage associated with PFM mode. The
NCP1501 does not contain an internal oscillator for the
switching mode. The Dual PWM/LDO mode is an exclusive
Patent Pending circuit.

The PWM clock is generated via an external clock signal

on the Synchronization pin. The operating frequency range
for the PWM is 500 kHz to 1000 kHz. The output current of
the PWM is typically 100 mA with a guarantee of over
300 mA for the 2.7 to 5.2 input voltage range.

If a synchronization pulse is not present, the NCP1501

changes into the LDO mode. The LDO function assures the
user of an extremely low output ripple voltage and greatly
reduced quiescent current when the users system is in a sleep
mode. Internally to the NCP1501, the Synchronization pin

has a pull down resistor to force the part into LDO mode
when a clock signal is not present. To place the NCP1501 in
LDO mode, the user must set the Synchronization pin low.
The LDO mode guarantees an output in excess of 50 mA.

Pins CB0 and CB1 control the output voltage selection.

The four voltages are 1.05 V, 1.35 V, 1.57 V, 1.8 V. CB0
contains a pull down resistor and CB1 contains a pull up
resistor internal to the NCP1501. The resistors force the
output of the converter to 1.35 V if the pins are floating
connections to the external circuit.

The Shutdown Pin enables the operation of the device.

The Shutdown Pin has an internal pull down resistor to force
the NCP1501 into the off mode if this pin is floating due to
the external circuit. During Startup, the NCP1501 has a soft
start function to limit fast dV/dt and eliminate overshoot on
the output.

Figure 3. Block Diagram and Circuit Schematic of the NCP1501

bat

Sync

SHD

DC/DC

CONTROL

LDO

CONTROL

CB0
CB1

out

lim

The external components required are an input and an

output 10 0

mF ceramic capacitor and a 10 mH inductor.

PWM Mode

During normal operation, a synchronization pulse acts as

the clock for the DC/DC controller. The rising edge of the
clock pulls the gate of Q1 low allowing the inductor to
charge. When the current through Q1 reaches either the
current limit or feedback voltage reaches its limit, Q1 will
turn off and Q2 will turn on. Q2 replaces the free wheeling
diode typically associated with Buck Converters. Q2 will
turn off when either a rising edge sync pulse is present or all
the stored energy is depleted from the inductor. Q3 remains
off during this mode.

The output voltage accuracy in the PWM mode is well

within 3% of the nominal set value. An over voltage
protection circuit is present in the PWM mode to limit the
positive voltage spike due to fast load transient conditions.
The PWM also has the ability to go to 100% duty cycle for
transient conditions and low input to output voltage
differentials.

In PWM mode, each switching cycle has a guaranteed

on-time of 100 ns. The NCP1501 has two protection circuits
that can eliminate the cycle. When tripped, the over voltage
protection or the thermal shutdown overrides the gate drive
of the high side MOSFET.

NCP1501

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Figure 4. PWM Circuit Schematic

Sync

bat

C1
10

C2
10

ref

ERROR

AMP

Latch

OCP

ref

+ 5%

Load

I PFET

COMP

OVP

COMP

Set

Ramp

LDO Mode

When the synchronization pulse is not present, the

NCP1501 operates as an LDO. The DC/DC Control
Circuitry will relinquish control of Q1 and turn off Q2. The

LDO Control Circuitry will turn on Q3 as a bypass circuit to
the inductor. Q1 is the controlling pass device of the LDO
that regulates the input to output voltage dropout. The LDO
can source an output current in excess of 50 mA.

Figure 5. LDO Circuit Schematic

Sync

bat

C1
10

C2
10

ref

ERROR

AMP

Switch/Invert

Out

Load

Set

Ramp

NCP1501

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Voltage Output Selection

The output voltage selection is accomplished via two

external pins: CB0 and CB1. If CB0 and CB1 pins are left
floating by the external circuit, the output voltage will
default to 1.35 V. The corresponding voltages are as follows.

NCP1501

CB0

CB1

out

(V)

1.05

1.35

1.57

1.80

Figure 6. Transition Waveforms from

LDO to PWM Mode

3.0

External SYNC Signal

Internal CLK Signal

TIME

(m)

1.35 V

Figure 7. Power Up and Power Down Sequence

1.8 V

1.05 V

1.57 V

SHD

CB0

CB1

Thermal Shutdown

Internal Thermal Shutdown circuitry is provided to

protect the integrated circuit in the event that the maximum
junction temperature is exceeded. When activated, typically
at 160

C, the PWM latch is reset and the linear regulator

control circuitry is disabled. The thermal shutdown circuit
is designed with 25

C of hysteresis. This means that the

PWM latch and the regulator control circuitry cannot be
re-enabled until the die temperature drops by this amount.
This feature is provided to prevent catastrophic failures from
accidental device overheating. It is not intended as a
substitute for proper heatsinking. The NCP1501 is
contained in the Micro-8 package.

NCP1501

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APPLICATIONS INFORMATION

NCP1501 is a dual mode PWM or LDO step down

converter. This dual mode takes advantage of the best of
each mode. There are three required external components:
an input and output capacitor and an inductor.

The PWM mode allows high efficiency for larger loads.

A typical efficiency for an input of 3.6 V and an output of
1.8

V and 100 mA is over 90%. Low R

DSon

and

synchronous rectification contained within the device
contributes to the very high efficiency. As with other
synchronous rectification devices, the NCP1501 does not
require an external diode to supplement the NFET during
switching on or off. A synchronization pin allows the user
to define the frequency noise spikes of the PWM. The duty
cycle of the synchronization signal must be within the range

of 30% to 70%. The rising edge of the signal from the
synchronization pin acts as the oscillator signal to set the
latch and reset the ramp compensation signal. An Over
Voltage Protection circuit ensures the output will respond
properly to fast transients from large to small loads. The
NCP1501 allows the PWM mode to enter a 100% duty cycle
for fast load transient conditions and low input to output
voltage differentials.

The LDO mode is effective during low load conditions by

lowering the quiescent current and reducing the output
ripple voltage associated with PWM converters entering
PFM mode. NCP1501 enters the LDO mode when a
synchronization signal is not present. It is recommended to
pull the synchronization signal low for LDO mode.

Figure 9. Typical Operating Schematic

out

NCP1501

SHD

SYN

CB0

CB1

GND

bat

out

, C

out

: 10

F Ceramic,

C2012X5R0J106M (TDK)
L: 10

H, LLF4017-100 (TDK)

Figure 10. Input Current versus Voltage for the

Shutdown Pin

SHD

(V)

SHD

(

2.5

1.5

0.5

= 3.6 V

= 25

Figure 11. Input Current versus Voltage for the

Synchronization Pin

SYN

(V)

SYN

(

1.8

1.2

0.2

= 3.6 V

= 25

0.4

0.6

0.8

1.4

1.6

NCP1501

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Low

Figure 12. Input Current versus Voltage for the

CB Pins

(V)

(

2.5

1.5

0.5

= 3.6 V

= 25

Figure 13. Input Current versus Voltage for the

Feedback Pin

1.5

0.5

(V)

(

-1

= 3.6 V

= 25

PWM Mode

Figure 14. V

Input Voltage versus

CB Threshold

(V)

CB(threshold)

(V)

0.93

0.89

0.88

0.85

0.84

= 25

LDO Mode

Figure 15. Transition Level of CB Pins

1.4

0.6

0.4

0.2

(V)

out

(V)

1.55

1.5

1.4

= 3.6 V

= 25

LDO Mode

1.3

1.35

1.45

Figure 16. Input Voltage versus

Shutdown Voltage

Figure 17. Output Voltage versus Shutdown

Pin Voltage

0.87

0.86

0.92

0.91

0.90

High

1.2

1.0

0.8

(V)

CB(threshold)

(V)

0.93

0.89

0.88

0.85

0.84

= 25

LDO Mode

1.4

0.6

0.4

0.2

(V)

out

(V)

1.8

= 25

LDO Mode

0.87

0.86

0.92

0.91

0.90

SHD

High

1.2

1.0

0.8

SHD

Low

SHD

Decreasing

SHD

Increasing

1.6

NCP1501

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Figure 18. Output Voltage versus

PWM Input Voltage

(V)

out

(V)

2.0

1.8

1.4

0.6

Figure 19. Input Voltage versus Output Voltage

0.2

0.4

1.2

0.8

1.0

1.6

out

(V)

1.05 V

out

1.35 V

out

1.57 V

out

1.80 V

out

2.0

1.8

1.4

0.6

0.2

0.4

1.2

0.8

1.0

1.6

1.05 V

out

1.35 V

out

1.57 V

out

1.80 V

out

1.8 V

out

1.35

Figure 20. Efficiency versus Output Current

300

250

200

150

100

out

, OUTPUT CURRENT (mA)

EFFICIENCY (%)

1.05

1.57

= 3.6 V

Freq = 600 kHz
T

= 25

See Figure 9 for Circuit

Figure 21. Efficiency versus Frequency

1000

900

800

700

600

500

FREQUENCY (kHz)

EFFICIENCY (%)

PWM

Figure 22. Input Current versus Output Current

Comparison for PWM and LDO Mode

1000

800

600

400

200

out

, OUTPUT CURRENT (

, INPUT CURRENT (

1200

1000

800

400

200

Figure 23. Efficiency versus Input Voltage

5.2

4.2

3.7

3.2

2.7

, INPUT VOLTAGE (V)

EFFICIENCY (%)

LDO

600

4.7

out

= 100 mA

Freq = 600 kHz
T

= 25

= 3.6 V

out

= 1.8 V

PWM Freq = 600 kHz

= 3.6 V

out

= 100 mA

1.05 V

out

1.35 V

out

1.57 V

out

1.80 V

out

1.8 V

out

1.35

1.05

1.57

NCP1501

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160

140

120

100

200

180

2.0 n

= 3.6 V

out

= 1.57 V

Load = 15

F = 1.0 MHz

Start 0 Hz

1.0 MHz

Stop 10 MHz

800

700

600

500

400

1.0 m

900

300

200

100

10 n

= 3.6 V

out

= 1.57 V

Load = 15

F = 600 kHz

Start 0 Hz

1.0 MHz

Stop 10 MHz

800

700

600

500

400

1.0 m

900

300

200

100

10 n

= 3.6 V

out

= 1.57 V

Load = 15

F = 600 kHz

Start 0 Hz

1.0 MHz

Stop 10 MHz

Figure 30. V

rms

versus Frequency

Figure 31. V

rms

versus Frequency

Figure 32. Noise versus Frequency

160

140

120

100

200

180

2.0 n

= 3.6 V

out

= 1.57 V

Load = 15

F = 1.0 MHz

Start 0 Hz

1.0 MHz

Stop 10 MHz

Figure 33. V

RMS

versus Frequency

805.4

129.3

854.3 nV

130.3 nV

NCP1501

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PACKAGE DIMENSIONS

Micro8

(MSOP-8)

DM SUFFIX

CASE 846A-02

ISSUE F

0.08 (0.003)

DIM

MIN

MAX

MIN

MAX

INCHES

MILLIMETERS

2.90

3.10

0.114

0.122

2.90

3.10

0.114

0.122

---

1.10

---

0.043

0.25

0.40

0.010

0.016

0.65 BSC

0.026 BSC

0.05

0.15

0.002

0.006

0.13

0.23

0.005

0.009

4.75

5.05

0.187

0.199

0.40

0.70

0.016

0.028

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. 846A-01 OBSOLETE, NEW STANDARD 846A-02.

-B-

-A-

PIN 1 ID

8 PL

0.038 (0.0015)

-T-

SEATING

PLANE

Micro8

inches

SCALE 8:1

1.04

0.041

0.38

0.015

5.28

0.208

4.24

0.167

3.20

0.126

0.65

0.0256

*For additional information on our Pb-Free strategy and soldering

details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.

SOLDERING FOOTPRINT*

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

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USA/Canada

Japan: ON Semiconductor, Japan Customer Focus Center

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Phone: 81-3-5773-3850

NCP1501/D

Micro8 is a trademark of International Rectifier.

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