NCP6361
Buck Converter with
Bypass Mode for RF Power
Amplifiers
The NCP6361, a PWM synchronous step−down DC−to−DC
converter, is optimized for supplying RF Power Amplifiers (PAs) used
in 3G/4G wireless systems (Mobile / Smart Phones, Tablets,…)
powered by single−cell Lithium−Ion batteries. The device is able to
deliver up to 2 A current in bypass mode and 800 mA in buck mode.
The output voltage is monitorable from 0.4 V to 3.5 V by an analog
control pin VCON. The analog control allows dynamically optimizing
the RF Power Amplifier’s efficiency through the monitoring of the PA
output power. With an improved overall system efficiency the
communication time and phone autonomy can be consequently
increased. At light load for optimizing the DC−to−DC converter
efficiency, the NCP6361 enters automatically in PFM mode and
operates in a slower switching frequency. The NCP6361 enters in
bypass mode when the desired output voltage becomes close to the
input voltage (e.g.: low battery conditions). The device operates at
3.429 MHz or 6 MHz switching frequency. This way the system
tuning can focus respectively either on a better efficiency (3.249 MHz)
or on employing smaller value inductor and capacitors (6 MHz).
Synchronous rectification and automatic PFM / PWM / By−Pass
operating mode transitions improve overall solution efficiency. The
NCP6361 has two versions: NCP6361A and NCP6361B. Version B
has a spread spectrum function for low EMI operation. The NCP6361
is available in a space saving, low profile 1.36 x 1.22 mm CSP−9
package.
Features
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MARKING
DIAGRAM
6361x
ALYWW
G
WLCSP9
CASE 567GM
6361x = Specific Device Code
x = A or B
A
= Assembly Location
L
= Wafer Lot
Y
= Year
WW = Work Week
G
= Pb−Free Package
ORDERING INFORMATION
See detailed ordering, marking and shipping information on
page 19 of this data sheet.
•
Input Voltage from 2.5 V to 5.5 V for Battery Powered
•
•
•
•
Applications
Adjustable Output Voltage (0.4 V to 3.50 V)
3.429 / 6 MHz Selectable Switching Frequency
Uses 470 nH Inductor and 4.7
mF
Capacitor for
Optimized Footprint and Solution Thickness
PFM /PWM/Bypass Automatic Mode Change for High
Efficiency
VBATT
•
•
•
•
Low 45
mA
Quiescent Current
Thermal Protections to Avoid Damage of the IC
Small 1.36 x 1.22 mm / 0.4 mm Pitch CSP Package
This is a Pb−Free Device
Typical Applications
•
3G / 4G Wireless Systems, Smart−Phones and Webtablets
NCP6361
Bypass
Enable
BPEN
Bypass Control
Vout Control
Bypass
PVIN
FB
Battery or
System
Supply
VCON
10uF
AGND
Thermal
Protection
FSEL
EN
Enabling
PGND
4.7uF
DCDC
SW
1.0A
3.43/6.00 MHz
0.47uH
V
OUT
Figure 1. NCP6361 Block Diagram
©
Semiconductor Components Industries, LLC, 2014
1
April, 2014 − Rev. 5
Publication Order Number:
NCP6361/D
NCP6361
VBATT
NCP6361
FB
GPI/O
BPEN
Bypass Control
Bypass
PVIN
DAC
VCON
Vout Control
Battery or
System
Supply
10uF
AGND
Thermal
Protection
GPI/O
FSEL
4.7uF
GPI/O
EN
Enabling
Rev 0.00
DCDC
SW
1.0A
3.43/6.00 MHz
0.47uH
DCDC Out
RF Transceiver
PGND
RF IN
RF TX
RF OUT
3G/4G PAs
Coupler
Antenna
Switch
Power
Envelop
Detection
Figure 2. Typical Application
PVIN
C3
C2
FB
Cin
Bypass
Control
LX
BPEN
C1
B3
SW
Logic
Block
VOUT
FSEL
B2
EN
B1
Cout
AGND
A2
PFM / PWM
Contoller
A 3
PGND
Thermal
Shutdown
Error
Amp
VCON
A1
Ramp
Generator
3.43 / 6 MHz
Figure 3. NCP6361 Internal Block Diagram
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2
NCP6361
1.36 mm
A1
VCON
B1
EN
A2
AGND
B2
FSEL
C2
FB
A3
PGND
1.22 mm
B3
SW
C3
PVIN
C1
BPEN
Figure 4. Pin Out (Top View)
PIN FUNCTION DESCRIPTION
Pin
A1
A2
A3
Name
VCON
AGND
PGND
Type
Input
Ground
Ground
Description
Voltage Control Analog Input. This pin controls the output voltage. It must be shielded to protect
against noise. V
OUT
= 2.5 x VCON
Analog Ground. Analog and digital modules ground. Must be connected to the system ground.
DC−DC Power Ground. This pin is the power ground and carries high switching current. High
quality ground must be provided to prevent noise spikes. To avoid high−density current flow in a
limited PCB track, a local large ground plane is recommended.
Enable Control. Active high will enable the part. There is an internal pull down resistor on this pin.
Frequency selection pin. Active low will select 6 MHz switching frequency. Active high will select
3.429 MHz switching frequency. Internal pull−down resistor connected to this pin.
DC−DC Switch Power. This pin connects the power transistors to one end of the inductor. Typical
application (6 MHz) uses 0.470
mH
inductor; refer to application section for more information.
Bypass Enable Pin. Set a high level to force bypass mode. Set a low level for auto−bypass mode.
Internal pull−down resistor connected to this pin.
DCDC Feedback Voltage. Must be connected to the output capacitor positive terminal. This is the
input to the error amplifier.
DCDC Power Supply. This pin must be decoupled to ground by a 10
mF
and 1
mF
ceramic
capacitor. These capacitors should be placed as close as possible to this pin.
B1
B2
B3
C1
C2
C3
EN
FSEL
SW
BPEN
FB
PV
IN
Input
Input
Power
Output
Input
Power
Input
Power
Input
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3
NCP6361
MAXIMUM RATINGS
Rating
Analog and power pins: PV
IN
, SW, FB
VCON pin
Digital pins: EN, BPEN & FSEL:
Input Voltage
Input Current
Operating Ambient Temperature Range
Operating Junction Temperature Range (Note 1)
Storage Temperature Range
Maximum Junction Temperature
Thermal Resistance Junction−to−Ambient (Note 2)
Moisture Sensitivity (Note 3)
Symbol
V
A
V
VCON
V
DG
I
DG
T
A
T
J
T
STG
T
JMAX
R
qJA
MSL
Value
−0.3 to + 7.0
−0.3 to + 2.5
−0.3 to V
A
+0.3
≤
7.0
10
−40 to +85
−40 to +125
−65 to + 150
−40 to +150
85
Level 1
Unit
V
V
V
mA
°C
°C
°C
°C
°C/W
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.
1. The thermal shutdown set to 165°C (typical) avoids potential irreversible damage on the device due to power dissipation.
2. The Junction−to−Ambient thermal resistance is a function of Printed Circuit Board (PCB) layout and application. This data is measured using
4−layer PCBs (2s2p). For a given ambient temperature T
A
it has to be pay attention to not exceed the max junction temperature T
JMAX
.
3. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A.
OPERATING CONDITIONS
Symbol
PV
IN
L
Co
Co
L
Co
Co
Cin
Parameter
Power Supply (Note 4)
Inductor for DCDC converter (Note 5)
Output Capacitor for DCDC Converter
(Note 5)
Output Capacitor for DCDC Converter
(Note 5)
Inductor for DCDC converter (Note 5)
Output Capacitor for DCDC Converter
(Note 5)
Output Capacitor for DCDC Converter
(Note 5)
Input Capacitor for DCDC Converter
(Note 5)
F = 6 MHz
F = 6 MHz, L = 0.47
mH
F = 6 MHz, L = 0.33
mH
F = 3.429 MHz
F = 3.429 MHz, L = 1
mH
F = 3.429 MHz, L = 0.47
mH
4.7
33
4.7
4.7
33
Conditions
Min
2.5
0.47
−
−
1
−
−
10
33
220
33
220
Typ
Max
5.5
Unit
V
mH
mF
mF
mH
mF
mF
mF
Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond
the Recommended Operating Ranges limits may affect device reliability.
4. Operation above 5.5 V input voltage for extended period may affect device reliability.
5. Including de−ratings (refer to application information section of this document for further details)
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4
NCP6361
ELECTRICAL CHARACTERISTICS
Min and Max Limits apply for T
A
up to +85°C unless otherwise specified. PV
IN
= 3.6 V (Unless otherwise noted). Typical values are
referenced to T
A
= + 25°C and default configuration
Symbol
SUPPLY CURRENT: PIN PV
IN
I
Q
Operating quiescent current
DCDC on – no load – no
switching, EN = High
T
A
= up to +85°C
PV
IN
= 2.5 V to 5.5 V
V
CON
< 0.1 V, EN = High
T
A
= up to +85°C
EN = Low
PV
IN
= 2.3 V to 5.5 V
T
A
= up to +85°C
−
45
60
mA
Parameter
Conditions
Min
Typ
Max
Unit
I
SLEEP
Product sleep mode current
−
55
70
mA
I
OFF
Product off current
−
0.9
3
mA
DCDC CONVERTER
PV
IN
V
OUT_MIN
V
OUT_MAX
Gain
V
OUT_ACC
F
SW1
F
SW2
R
ONHS
R
ONLS
R
ONBP
I
PKHS
I
PKLS
DC
MAX
h
Input Voltage Range
Minimum Output Voltage
Maximum Output Voltage
V
CON
to V
OUT
Gain
V
OUT
Accuracy
Switching Frequency
Switching Frequency
P−Channel MOSFET On Resistance
N−Channel MOSFET On Resistance
BP MOSFET On Resistance
Peak Inductor Current PMOS
Peak Inductor Current NMOS
Maximum Duty Cycle
Efficiency
PV
IN
= 3.6 V, V
OUT
= 0.8 V
I
OUT
= 10 mA, PFM mode
PV
IN
= 3.6 V, V
OUT
= 1.8 V
I
OUT
= 200 mA, PWM mode
PV
IN
= 3.9 V, V
OUT
= 3.3 V
I
OUT
= 500 mA, PWM mode
LINE
TR
Line Transient Response
PV
IN
= 3.6 V to 4.2 V
I
OUT
= 100 mA, V
OUT
= 0.8 V
T
R
= T
F
= 10
ms
PV
IN
= 3.1 V / 3.6 V / 4.5 V
I
OUT
= 50 to 150 mA
T
R
= T
F
= 0.1
ms
1.6
1.4
50
Ideal = 2.5 x V
CON
FSEL = 0
FSEL = 1
From PV
IN
to SW
T
J
up to +85°C, PV
IN
= 3.6 V
From SW1 to PGND
T
J
up to 85°C, PV
IN
= 3.6 V
From PV
IN
to FB
T
J
up to 85°C, PV
IN
= 3.6 V
−50
−3
5.4
3.085
−
−
−
−
−
−
6
3.429
177
100
217
1.4
1.0
100
75
90
95
%
mV
pk
V
CON
= 0.16 V (Note 8)
V
CON
= 1.40 V (Note 8)
2.5
0.35
3.45
−
0.40
3.50
2.5
+50
+3
6.6
3.772
−
−
−
−
−
−
5.5
0.45
3.55
V
V
V
V/V
mV
%
MHz
MHz
mW
mW
mW
A
A
%
%
%
LOAD
TR
Load Transient Response
50
mV
pk
V
CON_BP_EN
V
CON_BP_EX
Vcon Forced Bypass Mode Enter
Vcon Forced Bypass Mode Exit
V
V
6. Guaranteed by design and characterized.
7. Operation above 5.5 V input voltage for extended periods may affect device reliability.
8. Tested and guaranteed by correlation.
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