MPS MP2109 Dual 1.2mhz, 800ma synchronous step-down converter Datasheet

MP2109
Dual 1.2MHz, 800mA Synchronous
Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP2109 contains two independent 1.2MHz
constant frequency, current mode, PWM
step-down
converters.
Each
converter
integrates a main switch and a synchronous
rectifier for high efficiency without an external
Schottky diode. The MP2109 is ideal for
powering portable equipment that runs from a
single cell Lithium-Ion (Li+) battery. Each
converter can supply 800mA of load current
from a 2.5V to 6V input voltage. The output
voltage can be regulated as low as 0.6V. The
MP2109 can also run at 100% duty cycle for
low dropout applications.
•
•
•
•
•
•
•
•
•
•
•
•
EVALUATION BOARD REFERENCE
APPLICATIONS
Board Number
Dimensions
EV2109DQ-00A
1.5”X x 1.0”Y x 0.5”Z
•
•
•
•
•
•
Up to 95% Efficiency
1.2MHz Constant Switching Frequency
800mA Load Current on Each Channel
2.5V to 6V Input Voltage Range
Output Voltage as Low as 0.6V
100% Duty Cycle in Dropout
Current Mode Control
Short Circuit Protection
Thermal Fault Protection
<0.1µA Shutdown Current
Internally Compensated
Space Saving 10-Pin QFN Package
Cellular and Smart Phones
Microprocessors and DSP Core Supplies
PDAs
MP3 Players
Digital Still and Video Cameras
Portable Instruments
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
VIN1/IN2
2.5V to 6V
VOUT1
1.8V
800mA
1
10
2
3
IN2
EN1
SW1
100
EN2
MP2109
FB1
SW2
FB2
GND1
9
6
5
95
OFF ON
VOUT2
1.2V
800mA
7
90
EFFICIENCY (%)
OFF ON
8
IN1
VOUT=3.3V
85
80
75
70
65
60
GND2
55
4
50
MP2109_S01
0
500
LOAD CURRENT (mA)
1000
MP2109_EC01
MP2109 Rev.1.4
10/16/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
1
MP2109 – DUAL 1.2MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER
ABSOLUTE MAXIMUM RATINGS (1)
PACKAGE REFERENCE
TOP VIEW
EN1
1
10
SW1
FB1
2
9
GND1
IN2
3
8
IN1
GND2
4
7
FB2
SW2
5
6
EN2
EXPOSED PAD
ON BACKSIDE
MP2109_PD02_QFN10
Recommended Operating Conditions
Package
Temperature
MP2109DQ
QFN10
(3mm x 3mm)
–40°C to +85°C
For Tape & Reel, add suffix –Z (eg. MP2109DQ–Z)
For Lead Free, add suffix –LF (eg. MP2109DQ–LF–Z)
(2)
Supply Voltage VIN1/IN2 ....................... 2.5V to 6V
Output Voltage VOUT1/OUT2 .................. 0.6V to 6V
Operating Temperature .............–40°C to +85°C
Thermal Resistance
Part Number*
*
VIN1/IN2 to GND ............................ –0.3V to +6.5V
VSW1/SW2 to GND................... –0.3V to VIN + 0.3V
VFB1/FB2, VEN1/EN2 to GND ............. –0.3V to +6.5V
Junction Temperature.............................+150°C
Lead Temperature ..................................+260°C
Storage Temperature .............–65°C to +150°C
(3)
θJA
θJC
QFN10 (3mm x 3mm)............. 50 ...... 12... °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
3) Measured on approximately 1” square of 1 oz copper.
ELECTRICAL CHARACTERISTICS (4)
VIN1/IN2 = VEN1/EN2 = 3.6V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Each Converter Supply Current
VEN1/EN2 = VIN1/IN2, VFB1/FB2 = 0.65V
Each Converter Shutdown
VEN1/EN2 = 0V, VIN1/IN2 = 6V
Current
IN Under Voltage Lockout
Rising Edge
Threshold
IN Under Voltage Lockout
Hysteresis
TA = +25°C
Regulated FB Voltage
VFB
–40°C ≤ TA ≤ +85°C
FB Input Bias Current
IFB
VFB1/FB2 = 0.65V
PFET On Resistance
ISW1/SW2 = 100mA
NFET On Resistance
ISW1/SW2 = –100mA
VEN1/EN2 = 0V, VIN1/IN2 = 6V
SW Leakage Current
VSW1/SW2 = 0V or 6V
Duty Cycle = 100%,
PFET Current Limit
Current Pulse Width < 1ms
Oscillator Frequency
fOSC
Thermal Shutdown Trip
Threshold
EN Enable Threshold
–40°C ≤ TA ≤ +85°C
EN Input Current
VEN1/EN2 = 0V to 6V
Min
2.15
Typ
440
Max
600
Units
µA
0.10
1
µA
2.30
2.40
V
55
0.588
0.582
–50
0.600
0.600
0.5
0.42
0.26
–2
mV
0.612
0.618
+50
V
nA
Ω
Ω
+2
µA
0.9
1.3
1.8
A
0.99
1.24
1.49
MHz
°C
150
0.3
–1
0.96
1.5
+1
V
µA
Notes:
4) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.
MP2109 Rev.1.4
10/16/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
2
MP2109 – DUAL 1.2MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN1/IN2 = 3.3V, VOUT1 = 1.8V, VOUT2 = 1.2V, L1/2 = 4.7µH, CIN1/IN2 = 4.7µF, COUT1/OUT2 = 10µF, TA = +25°C,
unless otherwise noted.
Efficiency vs
Load Current
100
0.606
FEEDBACK VOLTAGE (V)
VOUT1=1.8V
EFFICIENCY (%)
90
VOUT2=1.2V
80
70
60
50
0.0
0.2
0.4
0.6
LOAD CURRENT (A)
Feedback Voltage vs
Temperature
0.604
0.602
0.600
0.598
0.596
0.594
-40 -20
0.8
0 +20 +40 +60 +80 +100
TEMPERATURE (°C)
MP2109-TPC01
MP2109-TPC02
Load Transient
Medium Load Operation
Heavy Load Operation
(IOUT=0mA to 500mA Step)
(IOUT=400mA)
(IOUT=800mA)
VOUT AC
100mV/div.
IL
0.5A/div.
VSW
2V/div.
VSW
2V/div.
VOUT AC
20mV/div.
VOUT AC
20mV/div.
IL
200mA/div.
ILOAD
0.5A/div.
IL
500mA/div.
400ns/div
MP2109-TPC03
400ns/div
MP2109-TPC04
Startup from Shutdown
Short Circuit Protection
Short Circuit Recovery
(No Load)
(No Load)
VEN
2V/div
VOUT
1V/div
IL
0.5A/div
MP2109-TPC06
MP2109 Rev.1.4
10/16/2006
MP2109-TPC05
VOUT
1V/div
VOUT
1V/div
IL
0.5A/div
IL
0.5A/div
MP2109-TPC07
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
MP2109-TPC08
3
MP2109 – DUAL 1.2MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS
Pin #
1
2
3
4
5
6
7
8
9
10
Name Description
Channel 1 Enable Control Input. Drive EN1 above 1.5V to turn on the Channel 1. Drive EN1
below 0.3V to turn it off (shutdown current < 0.1µA).
Channel 1 Feedback Input. Connect FB1 to the center point of the external resistor divider. The
FB1
feedback voltage is 0.6V.
IN2 Channel 2 Supply Input. Bypass to GND with a 2.2µF or greater ceramic capacitor.
GND2 Ground 2.
Channel 2 Power Switch Output. Inductor connection to drains of the internal PFET and NFET
SW2
switches.
Channel 2 Enable Control Input. Drive EN2 above 1.5V to turn on the Channel 2. Drive EN2
EN2
below 0.3V to turn it off (shutdown current < 0.1µA).
Channel 2 Feedback Input. Connect FB2 to the center point of the external resistor divider. The
FB2
feedback voltage is 0.6V.
IN1 Channel 1 Supply Input. Bypass to GND with a 2.2µF or greater ceramic capacitor.
GND1 Ground 1.
Channel 1 Power Switch Output. Inductor connection to drains of the internal PFET and NFET
SW1
switches.
EN1
MP2109 Rev.1.4
10/16/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
4
MP2109 – DUAL 1.2MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER
OPERATION
IN1/
IN2
EN1/
EN2
ICS
0.6V
SLOPE COMP
+
FB1/
FB2
+
IAMP
10X
-CURRENT
SENSE
AMP
BIAS
&
VOLTAGE
REFERENCE
FEEDBACK
ERROR\ EAMP
AMP
--
CC
17pF
EAO
+
+ PWMCMP
PWM
DH
MAIN
SWITCH
(PCH)
--
1.0MHz
OSCILLATOR
OSC
SW1/
SW2
PWM
CONTROL
LOGIC
SYNCHRONOUS
RECTIFIER
(NCH)
DL
GND1/
GND2
MP2109_BD02
Figure 1—Functional Block Diagram (Diagram represents ½ of the MP2109)
The MP2109 has dual independent constant
frequency current mode PWM step-down
converters. The MP2109 is optimized for low
voltage, Li-Ion battery powered applications
where high efficiency and small size are critical.
The MP2109 uses external resistor dividers to
set two output voltages independently from
0.6V to 6V. The device integrates both main
switches and synchronous rectifiers, which
provides high efficiency and eliminates the
need for an external Schottky diode. The
MP2109 can achieve 100% duty cycle. The
duty cycle D of each step-down converter is
defined as:
D = TON × f OSC × 100% =
VOUT
× 100%
VIN
Where TON is the main switch on time, fOSC is
the oscillator frequency (1.2MHz), VOUT is the
output voltage and VIN is the input voltage.
MP2109 Rev.1.4
10/16/2006
Current Mode PWM Control
Slope compensated current mode PWM control
provides stable switching and cycle-by-cycle
current limit for superior load and line response
and protection of the internal main switch and
synchronous rectifier. Each channel switches at
a constant frequency (1.2MHz) and regulates
the output voltage. During each cycle the PWM
comparator modulates the power transferred to
the load by changing the inductor peak current
based on the feedback error voltage. During
normal operation, the main switch is turned on
for a certain time to ramp the inductor current at
each rising edge of the internal oscillator, and
switched off when the peak inductor current is
above the error voltage. When the main switch
is off, the synchronous rectifier will be turned on
immediately and stay on until the next cycle
starts.
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
5
MP2109 – DUAL 1.2MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER
Dropout Operation
Each channel of the MP2109 allows the main
switch to remain on for more than one switching
cycle and increases the duty cycle while the
input voltage is dropping close to the output
voltage. When the duty cycle reaches 100%,
the main switch is held on continuously to
deliver current to the output up to the PFET
current limit. The output voltage then is the
input voltage minus the voltage drop across the
main switch and the inductor.
Maximum Load Current
The MP2109 can operate down to 2.5V input
voltage, however the maximum load current
decreases at lower input due to large IR drop
on the main switch and synchronous rectifier.
The slope compensation signal reduces the
peak inductor current as a function of the duty
cycle to prevent sub-harmonic oscillations at
duty cycles greater than 50%. Conversely the
current limit increases as the duty cycle
decreases.
Short Circuit Protection
The MP2109 has short circuit protection. When
any output is shorted to ground, the oscillator
frequency is reduced to prevent the inductor
current from increasing beyond the PFET
current limit. The PFET current limit is also
reduced to lower the short circuit current. The
frequency and current limit will return to the
normal values once the short circuit condition is
removed and the feedback voltage reaches
0.6V.
APPLICATION INFORMATION
Output Voltage Setting
The external resistor divider sets the output
voltage. The feedback resistor R1 also sets the
feedback loop bandwidth with the internal
compensation capacitor (see Figure 1).
Choose R1 around 300kΩ for optimal transient
response. R2 is then given by:
R2 =
R1
VOUT
−1
0 .6 V
L=
Table 1—Resistor Selection vs. Output
Voltage Setting
VOUT
R1
R2
1.2V
300kΩ (1%)
300kΩ (1%)
1.5V
300kΩ (1%)
200kΩ (1%)
1.8V
300kΩ (1%)
150kΩ (1%)
2.5V
300kΩ (1%)
95.3kΩ (1%)
MP2109 Rev.1.4
10/16/2006
Inductor Selection
A 1µH to 10µH inductor with DC current rating
at least 25% higher than the maximum load
current is recommended for most applications.
For best efficiency, the inductor DC resistance
shall be <200mΩ. See Table 2 for
recommended inductors and manufacturers.
For most designs, the inductance value can be
derived from the following equation:
VOUT × (VIN − VOUT )
VIN × ∆IL × fOSC
Where ∆IL is inductor ripple current. Choose
inductor ripple current approximately 30% of the
maximum load current, 800mA.
The maximum inductor peak current is:
IL(MAX ) = ILOAD +
∆IL
2
Under light load conditions below 100mA, larger
inductance is recommended for improved
efficiency. Table 3 lists inductors recommended
for this purpose.
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
6
MP2109 – DUAL 1.2MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER
Table 2—Suggested Surface Mount Inductors
Manufacturer
Part Number
Inductance (µH)
Max DCR (Ω)
Saturation
Current (A)
Dimensions
LxWxH (mm3)
Coilcraft
Toko
Sumida
LP03310-222ML
1002AS
CDRH3D16
2.2
2.2
2.2
0.15
0.11
0.072
1.1
1.14
1.20
3.3 x 3.3 x 1
4.6 x 4.6 x 1.2
4 x 4 x 1.8
Table 3—Inductors for Improved Efficiency at 25mA, 50mA, under 100mA Load.
Manufacturer
Part Number
Inductance (µH)
Max DCR (Ω)
Saturation
Current (A)
IRMS (A)
Coilcraft
Murata
Sumida
Sumida
DO1605T-103MX
LQH4C100K04
CR32-100
CR54-100
10
10
10
10
0.3
0.2
0.2
0.1
1.0
1.2
1.0
1.2
0.9
0.8
0.7
1.4
Input Capacitor Selection
The input capacitor reduces the surge current
drawn from the input and switching noise from
the device. The input capacitor impedance at
the switching frequency shall be less than input
source impedance to prevent high frequency
switching current passing to the input. Ceramic
capacitors with X5R or X7R dielectrics are
highly recommended because of their low ESR
and small temperature coefficients. For most
applications, a 4.7µF capacitor is sufficient.
Output Capacitor Selection
The output capacitor keeps output voltage
ripple small and ensures regulation loop stable.
The output capacitor impedance shall be low at
the switching frequency. Ceramic capacitors
with X5R or X7R dielectrics are recommended.
The output ripple ∆VOUT is approximately:
∆VOUT ≤
⎞
VOUT × (VIN − VOUT ) ⎛
1
⎟
× ⎜⎜ ESR +
VIN × f OSC × L
8 × f OSC × C3 ⎟⎠
⎝
MP2109 Rev.1.4
10/16/2006
Thermal Dissipation
Power dissipation shall be considered when
both channels of the MP2109 provide maximum
800mA output current to the loads at high
ambient temperature with low input supply
voltage. If the junction temperature rises above
150°C, the MP2109 two channels will be shut
down.
The junction-to-ambient thermal resistance of
the 10-pin QFN (3mm x 3mm) RΘJA is 50°C/W.
The maximum power dissipation is about 1.6W
when the MP2109 is operating in a 70°C
ambient temperature environment.
PD MAX =
150 o C − 70 o C
50 o C / W
= 1 .6 W
PC Board Layout
The high current paths (GND1/GND2, IN1/IN2
and SW1/SW2) should be placed very close to
the device with short, direct and wide traces.
Input capacitors should be placed as close as
possible to the respective IN and GND pins.
The external feedback resistors shall be placed
next to the FB pins. Keep the switching nodes
SW1/SW2 short and away from the feedback
network.
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
7
MP2109 – DUAL 1.2MHz 800mA SYNCHRONOUS STEP-DOWN CONVERTER
PACKAGE INFORMATION
QFN10 (3mm x 3mm)
2.90
3.10
0.30
0.50
PIN 1 ID
MARKING
0.18
0.30
2.90
3.10
PIN 1 ID
INDEX AREA
1.45
1.75
PIN 1 ID
SEE DETAIL A
10
1
2.25
2.55
0.50
BSC
5
6
TOP VIEW
BOTTOM VIEW
PIN 1 ID OPTION A
R0.20 TYP.
PIN 1 ID OPTION B
R0.20 TYP.
0.80
1.00
0.20 REF
0.00
0.05
SIDE VIEW
DETAIL A
NOTE:
2.90
0.70
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.
4) DRAWING CONFORMS TO JEDEC MO-229, VARIATION VEED-5.
5) DRAWING IS NOT TO SCALE.
1.70
0.25
2.50
0.50
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not
assume any legal responsibility for any said applications.
MP2109 Rev. 1.4
10/16/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
8