CHAMP CM3718IS

CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
GENERAL DESCRIPTION
FEATURES
The CM3718 is a low-noise, pulse-width-modulated (PWM),
DC-DC step-down converter. It powers logic and transmitters
in small wireless systems such as cellular phones,
communicating PDAs, and handy-terminals. The device
features an internal synchronous rectifier for high efficiency; it
requires no external Schottky diode. Excellent noise
characteristics and fixed-frequency operation provide easy
post-filtering. The CM3718 is ideally suited for Li-lon battery
applications. It is also useful for +3V or +5V fixed input
applications.
‹
Patent Number #6,452,366
‹
1.2MHz switching and synchronization
‹
Dynamic output-voltage adjustment from VREF to VIN
‹
1.5A Guaranteed Output Current
‹
95% Efficiency
‹
No Schottky Diode Required
‹
External Soft Start
‹
8-pin PSOP power packages
The device operates in one of four modes. Forced PWM
mode operates at a fixed frequency regardless of the load.
Shutdown mode places the device in standby, reducing
quiescent supply current to under 0.1μA.
The CM3718 can deliver over 1.5A. The output voltage can be
adjusted from VREF to VIN. The input range is from 2.0V to
5.0V. Other features of the CM3718 include high efficiency,
low dropout voltage. It is available in a space-saving 8-pin
SOP package.
APPLICATIONS
‹
Cellular Phone
‹
Cordless Phone
‹
PDAs and Handy-Terminals
‹
CPU I/O Supplies
‹
Notebook Chipset Supplies
‹
Battery Operated Devices
2006/10/11 Rev. 1.6
PIN CONFIGURATION
PSOP-8 (PT-08)
Top View
1
VIN
2
GND
3
SD
4
VREF
Champion Microelectronic Corporation
PVIN
8
LX
7
PGND
6
VFB
5
Page 1
CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
PIN DESCRIPTION
Pin No.
CM3718
Symbol
Description
Min.
1
VIN
Voltage supply for internal circuits
2
GND
Ground for internal reference voltage divider
3
SD
2
Shutdown level
CMOS input level
Operating Rating
Typ.
Max.
Enable level
4
VREF
VOUT Set Voltage
5
VFB
Feedback node for the VOUT
6
PGND
Ground for output power transistors
7
LX
Inductor connection to the Drains of the internal power MOSFETs
8
PVIN
Voltage supply for output power transistors
2.5
5.5
V
0.75 x VIN
VIN + 0.3
V
0
2.0
1.1
VIN
VREF
2
2.5
5.5
V
5.5
V
Part Number
Temperature Range
Package
CM3718IS
-40℃ to 85℃
8-Pin PSOP (PS08)
CM3718GIS*
-40℃ to 85℃
8-Pin PSOP (PS08)
*Note: G : Suffix for Pb Free Product
BLOCK DIAGRAM
GND
SD
PVIN
1
3
8
2
Oscillator Ramp Generator
PW M Controller
VREF
4
2006/10/11 Rev. 1.6
Error Amp
MOS
7
LX
Thermal
Protection
5
6
VFB
PG ND
Champion Microelectronic Corporation
V
V
ORDERING INFORMATION
VIN1
Uni
t
Page 2
CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are those values beyond which the
Junction Temperature ...…………………… …………150°C
device could be permanently damaged.
Storage Temperature ……................……. -65°C to 125°C
PVIN/VIN ………….....................................….......-0.3V to 6.0V
Lead Temperature (Soldering, 5 sec)……………….. 260°C
Thermal Dissipation(θJC )….. ………………….. .50°C/W
Voltage on Any Other Pin ………... GND – 0.3V to VIN + 0.3V
Output Current, Source or Sink ……......…………........…...1.5A
OPERATING CONDITIONS
Temperature Range ............................. -40°C to 85°C
PVIN Operating Range .........................2.0V to 4.0V
ELECTRICAL CHARACTERISTICS
(Unless otherwise stated, these specifications apply TA=25°C;
VIN=+3.3V and PVIN=+3.3V) maximum ratings are stress ratings only and functional device operation is not implied.
(Note 1)
Symbol
Parameter
CM3718
Test Conditions
Min.
Typ.
Max.
Unit
SWITCHING REGULATOR
VREF
Adjustable Output Voltage
VREF
VIN
1.2
V
fsw
Switching Frequency
CM3718
IOUT(RMS)
Maximum Output RMS Current
CM3718
1.5
MHz
A
IOUT(PEAK)
Maximum Output Peak Current
CM3718
3
A
Drain to Source on-State Resistance
PVIN=5V
MOSFETs
RDS(ON)
250
mΩ
220
μA
500
μA
SUPPLY
IVIN
IPVIN
2006/10/11 Rev. 1.6
Quiescent Current
VFB = 1.4V
LC unconnected
VFB = 1.4V
LC unconnected
Champion Microelectronic Corporation
Page 3
CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
FUNCTIONAL DESCRIPTION
The CM3718 step-down, pulse-width-modulated (PWM),
INPUTS
DC-DC converter has an adjustable output range from VREF
The input voltage reference pin, VREF determine the output
to the input voltage (VIN). An internal synchronous rectifier
voltages (LX). If a specific voltage is forced at the VREF pin, the
improves efficiency and eliminates an external Schottky diode. output voltage follows the voltage at the VREF pin.
Fixed-frequency operation enables easy post-filtering, thereby
providing excellent noise characteristics. As a result, the
OTHER SUPPLY VOLTAGES
CM3718 is an ideal choice for many small wireless systems.
Several inputs are provided for the supply voltages: PVIN and
VIN.
VREF
The PVIN provide the power supply to the power MOSFETs.
The reference voltage could be ranged from 1.1V to VIN.
VIN provides the voltage supply to the logic section and internal
error amplifiers.
OUPUTS
The output voltage pins (LX) are tied to the RF power amp,
FEEDBACK
via an external inductor. Output voltage is determined by the
The VFB pin is an input that can be used for closed loop
VREF inputs.
compensation. This input is derived from the voltage output.
AGND pin is a contact node of internal resistor divider for
remote sense.
APPLICATION CIRCUIT
NOTE:
VDD
JP3---->USEING EXTERNAL
VOLTAGE SETING BOARD
(PIN 1,2 SHORT)
C1 100uf/6.3V
R4
470
2
5
6
R7
0
U3
VFB
PVIN
PGND
7
2
8
1
SK12
CM3718-8PIN
C6
47uf/6.3V
2
U2 CM-431
1
R5
0
R8
5.1
105 C4
1
2
3
CON3
JP2
C5 104P
JP4
2006/10/11 Rev. 1.6
JP3
2
JUMPER
VDD
4
1
1
2
3
2
VCC
3
VREF
J2
VTT
SD
1
VIN
C7
104
1
2
C3
470
1
D2
J3
VREF-OUT
R1
100k
C2 105
L1
3.3uH/2A
2
1
R2
1k
2
LX
3
J1
PWR/IN
JP1
JUMPER
GND
4
TP1
BNC
1
VCC
1
D1
SK12
2
5
2
1
on/off sw
2
1
R3
100k
Champion Microelectronic Corporation
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CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
LOAD REGULATION
Vin=5V, VREF input=1.09V
Vin=5V, VREF input=4.04V
CM3718
CM3718
5
Vout(V)
Vout(V)
2
1
4
8
0.
1
6
4
0.
0.
2
0.
05
0.
1
0.8
0.6
0.4
0.2
0.05
3
0
Iout(A)
Iout(A)
LOAD TRANSIENT RESPONSE
CM3718 Transient Response VREF=1V, (IOUT from 1.5A- 0A) CM3718 Transient Response VREF=1V, (IOUT from 0A- 1.5A)
CM3718 Transient Response VREF=4V,(IOUT from 1.5A- 0A) CM3718 Transient Response VREF=4V,(IOUT from 0A- 1.5A)
2006/10/11 Rev. 1.6
Champion Microelectronic Corporation
Page 5
CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
VOUT OUTOUT RIPPLE AND NOISE
CM3718 VREF=1V, Load=0.5A
CM3718 VREF=1V, Load=1.0A
CM3718 VREF=1V, Load=1.5A
CM3718 VREF=4V, Load=0.5A
CM3718 VREF=4V, Load=1.0A
CM3718 VREF=4V, Load=1.5A
VOLTAGE SETTING STEP RESPONSE
CM3718 (VREF from 1V- 4V), Load=0.5A
CM3718 VREF=1V-4V, Load=1.0A
CM3718 VREF=1V-4V, Load=1.5A
CM3718 VREF=4V-1V, Load=0.5A
CM3718 VREF=4V-1V, Load=1.0A
CM3718 VREF=4V-1V, Load=1.5A
2006/10/11 Rev. 1.6
Champion Microelectronic Corporation
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CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
IN-RUSH CURRENT
CM3718 Vin=5V, VREF=1V, Load=1.5A, Ip-p=1.81A
CM3718 Vin=5V, VREF=4V, Load=1.5A, Ip-p=1.81A
EFFICIENCY
CM3718 efficiency (VOUT=1V, load from 0.05A~1.5A)
CM3718 efficiency (VOUT =4V, load from 0.05A~1.5A)
CM3718
CM3718
100.0%
100.0%
98.0%
95.0%
96.0%
94.0%
85.0%
Efficiency
80.0%
75.0%
92.0%
90.0%
88.0%
86.0%
70.0%
1.5
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
Iout(A)
Iout(A)
2006/10/11 Rev. 1.6
0.2
1.5
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
80.0%
0.05
82.0%
60.0%
0.1
84.0%
65.0%
0.05
Efficiency
90.0%
Champion Microelectronic Corporation
Page 7
CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
PCB LAYOUT
Top layer
Bottom Layer
Silkscreen Top
Sold-mask
Top
Sold-mask Bottom
2006/10/11 Rev. 1.6
Champion Microelectronic Corporation
Page 8
CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
PACKAGE DIMENSION
8-PIN PSOP (PS08)
θ
θ
2006/10/11 Rev. 1.6
Champion Microelectronic Corporation
Page 9
CM3718
1.5A LOW-NOISE PWM STEP-DOWN REGULATOR
IMPORTANT NOTICE
Champion Microelectronic Corporation (CMC) reserves the right to make changes to its products or to discontinue
any integrated circuit product or service without notice, and advises its customers to obtain the latest version of
relevant information to verify, before placing orders, that the information being relied on is current.
A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe
property or environmental damage. CMC integrated circuit products are not designed, intended, authorized, or
warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of
CMC products in such applications is understood to be fully at the risk of the customer. In order to minimize risks
associated with the customer’s applications, the customer should provide adequate design and operating
safeguards.
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Sales & Marketing
5F, No. 11, Park Avenue II,
Science-Based Industrial Park,
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7F-6, No.32, Sec. 1, Chenggong Rd.,
Nangang District, Taipei City 115, Taiwan
T E L : +886-3-567 9979
F A X : +886-3-567 9909
http://www.champion-micro.com
T E L : +886-2-2788 0558
F A X : +886-2-2788 2985
2006/10/11 Rev. 1.6
Champion Microelectronic Corporation
Page 10