MP2108DQ MPS [Monolithic Power Systems], MP2108DQ Datasheet - Page 3

• Manufacturer Part Number: MP2108DQ
• Description: 2A, 6V, 740KHz Synchronous Buck Converter
• Manufacturer: MPS [Monolithic Power Systems]

ELECTRICAL CHARACTERISTICS
V
PIN FUNCTIONS
MP2108 Rev 1.1
10/2/2006
Parameter
Oscillator
Switching Frequency
Maximum Duty Cycle
Minimum On Time
Error Amplifier
Voltage Gain
Transconductance
COMP Maximum Output Current
FB Regulation Voltage
FB Input Bias Current
Soft-Start
Soft-Start Current
Output Switch On-Resistance
Switch On Resistance
Synchronous Rectifier On Resistance
Switch Current Limit (Source)
Synchronous Rectifier Current Limit
(Sink)
Thermal Shutdown
IN
Pin #
= 5.0V, T
10
1
2
3
4
5
6
7
8
9
COMP
PGND
SGND
Name
VREF
A
RUN
BST
VIN
SS
LX
FB
= +25°C, unless otherwise noted.
Description
Power Switch Boost. BST powers the gate of the high-side N-Channel power MOSFET
switch. Connect a 10nF or greater capacitor between BST and LX.
Internal Power Input. VIN supplies the power to the MP2108 through the internal LDO
regulator. Bypass VIN to PGND with a 10µF or greater capacitor. Connect VIN to the input
source voltage.
Output Switching Node. LX is the source of the high-side N-Channel switch and the drain
of the low-side N-Channel switch. Connect the output LC filter between LX and the output.
Power Ground. PGND is the source of the N-Channel MOSFET synchronous rectifier.
Connect PGND to SGND as close to the MP2108 as possible.
Signal Ground.
Soft-Start Input. Place a capacitor from SS to SGND to set the soft-start period. The
MP2108 sources 2µA from SS to the soft-start capacitor at start-up. As the voltage at SS
rises, the feedback threshold voltage increases to limit inrush current at startup.
Feedback Input. FB is the inverting input of the internal error amplifier. Connect a resistive
voltage divider from the output voltage to FB to set the output voltage.
Compensation Node. COMP is the output of the error amplifier. Connect a series RC
network to compensate the regulation control loop.
Internal 2.4V Regulator Bypass. Connect a 10nF capacitor between VREF and SGND to
bypass the internal regulator. Do not apply any load to VREF.
On/Off Control Input. Drive RUN high to turn on the MP2108, drive RUN low to turn the
MP2108 off. For automatic startup, connect RUN to VIN via a 100kΩ pull-up resistor.
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
MP2108 – 2A, 6V, 740KHz SYNCHRONOUS BUCK CONVERTER
Symbol Condition
D
A
G
T
V
f
I
© 2006 MPS. All Rights Reserved.
I
SW
MAX
VEA
FB
SS
ON
FB
EA
www.MonolithicPower.com
V
V
V
V
V
V
FB
FB
IN
IN
IN
IN
(continued)
= 5V
= 3V
= 5V
= 3V
= 0.7V
= 0.9V
Min
620
875
2.5
85
–100
Typ
740
200
400
450
±40
895
190
280
160
230
350
160
3.5
2
Max
920
915
Units
µA/V
KHz
V/V
mV
mΩ
mΩ
mΩ
mΩ
mA
µA
nA
µA
ns
°C
%
A
3