MPS MP2101 1.6mhz synchronous step-down plus 200ma ldo Datasheet

TM
MP2101
1.6MHz Synchronous Step-Down
plus 200mA LDO
The Future of Analog IC Technology
TM
DESCRIPTION
FEATURES
The MP2101 is an internally compensated
1.6MHz fixed-frequency PWM step-down
switcher with a 200mA low dropout (LDO) linear
regulator. It is ideal for portable equipment
powered by a single cell Lithium-Ion (Li+)
Battery. The MP2101 can provide 800mA and
200mA of load current from a 2.5V to 6V input
voltage. Both output voltages can be regulated
as low as 0.6V.
•
•
•
•
•
The 800mA output channel features an
integrated high-side switch and synchronous
rectifier for high efficiency without an external
Schottky diode. With peak current mode control
and internal compensation, the MP2101 can be
stabilized with ceramic capacitors and small
inductors. The high-side switch can maintain
100% duty cycle in dropout condition.
The 200mA LDO output is used to power noise
sensitive circuitry. It has a separate input supply
to reduce power dissipation and noise from the
main switcher. Dropout voltage is 280mV under
a 150mA load. Fault condition protection
includes cycle-by-cycle current limiting and
thermal shutdown.
•
•
•
•
•
•
•
•
•
0.8A Switcher Output and 0.2A LDO Output
VIN1 Range for Switcher: 2.5V to 6V
VIN2 Range for LDO: 1.2V to VIN1
Internal Power MOSFET Switches
Stable with Low ESR Output Ceramic
Capacitors
Up to 93% Efficiency
0.01µA Shutdown Current
1.6MHz Fixed Switching Frequency
Up to 100% Switcher Duty Cycle
Thermal Shutdown
Cycle-by-Cycle Over Current Protection
Short Circuit Protection
Power On Reset Output
Available in 3x3 10-Pin QFN Packages
APPLICATIONS
•
•
•
•
•
DVD+/-RW Drives
Smart Phones
PDAs
Digital Cameras
Portable Instruments
“MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic
Power Systems, Inc.
The MP2101 is available in small 3mm x 3mm
10-pin QFN packages.
TYPICAL APPLICATION
Efficiency vs
Load Current
100
OUT1
1.8V @ 600mA
2
3
L1
4
6
1
EN1
IN1
EN2
PWROK
SW1 MP2101 OUT2
IN2
FB2
FB1
GND
9
POWER OK
8
7
10
5
OUT2
1.2V @ 200mA
VIN=3.3V
90
EFFICIENCY (%)
OFF ON
VIN
2.5V - 6V
80
VIN=4.2V
70
60
VIN=5.0V
50
40
10
MP2101 Rev. 1.0
8/18/2006
100
LOAD CURRENT (mA)
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1000
1
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
ABSOLUTE MAXIMUM RATINGS (1)
PACKAGE REFERENCE
TOP VIEW
FB1
1
10
FB2
EN1
2
9
EN2
IN1
3
8
PWROK
SW1
4
7
OUT2
GND
5
6
IN2
IN1, OUT1/2 to GND ................. –0.3V to + 6.5V
IN2 to GND ......................... –0.3V to VIN1 + 0.3V
SW1 to GND....................... –0.3V to VIN1 + 0.3V
PWROK to GND ......................... –0.3V to +6.5V
FB1/2, EN1/2 to GND ................. –0.3V to +6.5V
Operating Temperature .............–40°C to +85°C
Junction Temperature...............................150°C
Lead Temperature ....................................260°C
Storage Temperature .............–65°C to +150°C
Recommended Operating Conditions
Supply Voltage VIN1 ........................... 2.5V to 6V
Supply Voltage VIN2 ..........................1.2V to VIN1
Output Voltage VOUT1/2 ....................... 0.6V to 6V
Operating Temperature .............–40°C to +85°C
EXPOSED PAD
ON BACKSIDE
Thermal Resistance
Part Number*
MP2101DQ
*
Package
QFN10
(3mm x 3mm)
(2)
Temperature
–40°C to +85°C
For Tape & Reel, add suffix –Z (eg. MP2101DQ–Z)
For RoHS compliant packaging, add suffix –LF (eg.
MP2101DQ–LF–Z)
(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)
VIN1/2 = VEN1/2 = 3.6V, TA = +25°C, unless otherwise noted.
Parameters
Condition
No Load Supply Current
VFB1/2 = 0.62V
VEN1 = 0V, VEN2 = 3.6V
VEN1 = 3.6V, VEN2 = 0V
VEN1/2 = 0V, VIN1/2 = 6V
Hysteresis = 20°C
FB1/2 with respect to the Nominal Value
FB1/2 with respect to the Nominal Value
ISINK = 5mA
Switching Regulator
LDO
–40°C ≤ TA ≤ +85°C
Shutdown Current
Thermal Shutdown Trip Threshold
PWROK Upper-Trip Threshold
PWROK Lower-Trip Threshold
PWROK Output Lower Voltage
PWROK Deglitch Timer (FB1)
PWROK Deglitch Timer (FB2)
EN1/2 Trip Threshold
EN1/2 Pull-Down Resistor
Switching Regulator
IN1 Under Voltage Lockout Threshold Rising Edge
IN1 Under Voltage Lockout Hysteresis
TA = +25°C
Regulated FB1Voltage
–40°C ≤ TA ≤ +85°C
FB1 Input Bias Current
VFB1 = 0.62V
MP2101 Rev. 1.0
8/18/2006
Min
Typ
Max
Units
400
80
300
0.01
150
10
–10
550
100
400
1
µA
µA
µA
µA
°C
%
%
V
0.3
0.3
1.5
0.588
0.582
–50
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50
150
0.96
900
2.0
100
0.600
–2
µs
1.5
V
kΩ
2.5
V
mV
0.612
0.618
+50
V
nA
2
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
ELECTRICAL CHARACTERISTICS (4) (continued)
VIN1/2 = VEN1/2 = 3.6V, TA = +25°C, unless otherwise noted.
Parameters
SW1 PFET On Resistance
SW1 NFET On Resistance
SW1 Leakage Current
SW1 PFET Peak Current Limit
Oscillator Frequency
Linear Regulator LDO
IN2 Input Range
Regulated FB2 Voltage
FB2 Input Bias Current
OUT2 Short Circuit Foldback
OUT2 Output Current
Dropout Voltage (5)
Condition
ISW1 = 100mA
ISW1 = –100mA
VEN1 = 0V, VIN = 6V
VSW1 = 0V or 6V
Duty Cycle = 100%,
Current Pulse Width < 1ms
ILOAD = 10mA, VOUT2=VFB2
TA = +25°C
–40°C ≤ TA ≤ +85°C
VFB2 = 0.6V
VOUT2 = 0V
VOUT = 1.2V
ILOAD = 150mA, VOUT2 = 1.2V
Min
Typ
0.35
0.25
–2
Max
Units
Ω
Ω
+2
µA
0.9
1.4
2.0
A
1.2
1.6
2.0
MHz
VIN1
0.612
0.618
+50
V
1.2
0.588
0.582
–50
0.600
–2
180
200
280
V
nA
mA
mA
mV
Notes:
4) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.
5) The dropout voltage is equal to VIN2 – VOUT2 when VOUT2 is 100mV below the nominal value.
PIN FUNCTIONS
Pin #
Name
1
2
FB1
EN1
3
4
5
6
7
8
9
10
Description
Feedback 1. Feedback Input for the switcher output (OUT1).
Enable 1. Enable input for the switcher. Pull high to turn on the switcher; low to turn it off.
Input 1. Main input supply for both the switcher and the auxiliary low dropout (LDO) linear
IN1
regulator.
SW1
Switcher Switch Node. Output for the 800mA switcher channel.
GND
Ground.
IN2
Input 2. Input supply for the auxiliary linear regulator LDO output power device.
Output 2. Output of the 200mA LDO. The LDO is designed to be stable with an external
OUT2
minimum 1µF ceramic capacitor at 200mA of load current.
Power On Reset Open Drain Output. A high output indicates that both outputs are within
±10% of the regulation value. A low output indicates that the output is outside of the ±10%
PWROK window. PWROK is pulled down if EN1 and/or EN2 is low. The PWROK window comparators
have a 50µs deglitch timer for the switcher and 150µs deglitch timer for the linear regulator
LDO to avoid a false trigger during load transient.
Enable 2. Enable input for the linear regulator LDO. Pull high to turn on the LDO; low to turn it
EN2
off.
FB2
Feedback 2. Feedback input for the linear regulator output (OUT2).
MP2101 Rev. 1.0
8/18/2006
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TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6V, VOUT1 = 1.8V, VOUT2 = 1.2V, CIN1 = 4.7µF, CIN2 = 1µF, CO1 = 10µF, CO2 = 1µF, L = 2.2µH,
TA = +25°C, unless otherwise noted.
Efficiency vs
Load Current
95
80
85
70
VIN=3.3V
60
VIN=4.2V
50
40
VIN=5.0V
30
65
VIN=4.2V
55
VIN=5.0V
45
100
LOAD CURRENT (mA)
1000
65
45
35
25
10
100
LOAD CURRENT (mA)
1000
10
Efficiency vs
Load Current
VIN=4.2V
55
VIN=5.0V
45
60
25
40
VIN=5.0V
VIN=4.2V
1.80
VIN=3.3V
1.79
VIN=5.0V
1.78
1.77
0
200 400 600 800
LOAD CURRENT (mA)
MP2101 Rev. 1.0
8/18/2006
1000
OUTPUT VOLTAGE (V)
2.52
1.81
100
LOAD CURRENT (mA)
60
50
30
1000
10
100
LOAD CURRENT (mA)
1000
Output Voltage vs
Load Current
3.33
VIN=4.2V
2.50
VIN=3.3V
2.48
VIN=5.0V
2.46
2.44
2.42
2.40
VIN=5.0V
70
Output Voltage vs
Load Current
1.82
VIN=4.2V
80
40
10
1000
Output Voltage vs
Load Current
1.76
VIN=4.2V
70
50
100
LOAD CURRENT (mA)
90
80
35
10
VIN=3.3V
3.32
OUTPUT VOLTAGE (V)
65
1000
Efficiency vs
Load Current
EFFICIENCY (%)
EFFICIENCY (%)
75
100
LOAD CURRENT (mA)
100
90
VIN=3.3V
VIN=5.0V
55
100
85
VIN=4.2V
75
25
10
95
EFFICIENCY (%)
85
VIN=3.3V
75
Efficiency vs
Load Current
OUTPUT VOLTAGE (V)
95
35
20
10
Efficiency vs
Load Current
EFFICIENCY (%)
90
EFFICIENCY (%)
EFFICIENCY (%)
Efficiency vs
Load Current
3.31
VIN=4.2V
3.30
VIN=5.0V
3.29
3.28
3.27
3.26
0
200 400 600 800
LOAD CURRENT (mA)
1000
3.25
0
200 400 600 800
LOAD CURRENT (mA)
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4
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, VOUT1 = 1.8V, VOUT2 = 1.2V, CIN1 = 4.7µF, CIN2 = 1µF, CO1 = 10µF, CO2 = 1µF, L = 2.2µH,
TA = +25°C, unless otherwise noted.
Output Voltage vs
Load Current
VOUT2 = 1.5V
VOUT2 = 2.5V
1.54
1.52
VIN=3.3V
1.50
LDO
1.48
0
40
80
120 160
LOAD CURRENT (mA)
200
Output Voltage vs
Load Current
1.206
OUTPUT VOLTAGE (V)
2.53
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.56
Output Voltage vs
Load Current
2.52
2.51
VIN=3.3V
2.50
LDO
2.49
PSRR vs
Frequency
0
40
80
120 160
LOAD CURRENT (mA)
200
LDO
1.202
1.8
70
60
50
40
30
20
1.7
1.6
1.5
1.4
10
10
100
1K
10K 100K
FREQUENCY (Hz)
1M
1.3
4.0
LDO Dropout vs
Load Current
0
40
80
120 160
LOAD CURRENT (mA)
200
0.62
FEEDBACK VOLTAGE (V)
FREQUENCY (MHz)
80
VIN=1.8V
1.203
Feedback Voltage vs
Temperature
90
PSRR (dB)
1.204
Frequency vs
Input Voltage
100
0
1.205
4.4
4.8
5.2
5.6
INPUT VOLTAGE (V)
6.0
0.61
0.60
FB2
FB1
0.59
0.58
-40
-10 +20 +50 +80 +110 +140
TEMPERATURE (°C)
Enable Turn On
Enable Turn Off
EN = 3.6V, IOUT1 = 0.3A,
IOUT2 = 0.1A Resistive Load
EN = 3.6V, IOUT1 = 0.3A,
IOUT2 = 0.1A Resistive Load
DROPOUT VOLTAGE (V)
0.5
EN
2V/div.
PWROK
2V/div.
0.4
0.3
0.2
VOUT1
1V/div.
0.1
0.0
VOUT2
1V/div.
0
50
100 150 200
LOAD CURRENT (mA)
MP2101 Rev. 1.0
8/18/2006
EN
5V/div.
PWROK
5V/div.
VOUT1
1V/div.
VOUT2
1V/div.
250
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5
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 3.6V, VOUT1 = 1.8V, VOUT2 = 1.2V, CIN1 = 4.7 µF, CIN2 = 1µF, CO1 = 10µF, CO2 = 1µF, L = 2.2µH,
TA = +25°C, unless otherwise noted.
Input Ramp Up
Input Ramp Down
EN = 4V, IOUT1 = 0.3A,
IOUT2 = 0.1A Resistive Load
EN = 4V, IOUT1 = 0.3A,
IOUT2 = 0.1A Resistive Load
Heavy Load Ripple
EN1 = VIN = 5V,
IOUT1 = 0.8A Resistive Load
VOUT1
10mV/div.
VIN
2V/div.
VIN
2V/div.
VOUT1
2V/div.
VOUT1
1V/div.
VOUT2
1V/div.
VOUT2
1V/div.
VSW
2V/div.
IL
0.5A/div.
1ms/div.
PWROK Off vs
VOUT1 Shorted
PWROK Off vs
VOUT2 Shorted
EN = 4V, IOUT1 = 0.3A,
IOUT2 = 0.1A Resistive Load
PWROK
2V/div.
IL
0.5A/div.
Switcher Load Transient
LDO Load Transients
IOUT1 = 0.8A Resistive Load
VIN2 = 3.3V, VOUT2 = 1.2V,
IOUT2 = 0.02A to 0.15A Resistive Load
IL
0.5A/div.
MP2101 Rev. 1.0
8/18/2006
IOUT1 = 0.3A Resistive Load
VOUT1
2V/div.
VSW
5V/div.
VOUT2
1V/div.
VOUT1
0.1V/div.
Over Current Protection
EN = 4V, IOUT1 = 0.3A,
IOUT2 = 0.1A Resistive Load
PWROK
2V/div.
VOUT1
1V/div.
VOUT1
1V/div.
VOUT2
1V/div.
400ns/div.
VOUT2
50mV/div.
IOUT2
0.1A/div.
LDO Over Current
Protection
VIN2 = 3.3V, VOUT2 = 2.5V
VOUT2
1V/div.
IOUT2
0.1A/div.
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6
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
OPERATION
The MP2101 uses an external resistor divider to
set both the switcher and LDO output voltage
from 0.6V to 6V.
The MP2101 is a fixed-frequency 1.6MHz,
800mA current mode PWM step-down switcher
with a 200mA low dropout (LDO) linear
regulator. The MP2101 is optimized for low
voltage, Li-Ion battery powered applications
where high efficiency and small size are critical.
IN1 3
EN1/2 2/9
ICS
0.6V
+
SLOPE COMP
FB1 1
+
IAMP
10X
-CURRENT
SENSE
AMP
BIAS
&
VOLTAGE
REFERENCE
+
FEEDBACK
ERROR EAMP1
AMP
--
+ PWMCMP
EAO1
DH
MAIN
SWITCH
(PCH)
--
1.6MHz
OSCILLATOR
CC
17pF
PWM
OSC
PWM
CONTROL
LOGIC
4 SW1
SYNCHRONOUS
RECTIFIER
(NCH)
DL
5 GND
6
+
FB2 10
EAMP2
0.6V
FB1/2
0.66V
EAO2
--
+
7 OUT2
OUT_Hi
-POWER ON RESET
WINDOW
COMPARATORS
0.54V
+
IN2
8 PWROK
NO
GOOD
OUT_Lo
--
Figure 1—MP2101 Function Diagram
MP2101 Rev. 1.0
8/18/2006
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7
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
800mA Step-Down Switcher
The switcher integrates both a main switch and
a synchronous rectifier, which provides high
efficiency and eliminates the need for an
external Schottky diode.
This switcher can achieve 100% duty cycle.
The duty cycle (D) of a step-down switcher is
defined as:
D = TON × fOSC × 100% ≈
VOUT
× 100%
VIN
Where TON is the main switch on time and fOSC
is the oscillator frequency (1.6MHz).
Current Mode PWM Control
Slope compensated current mode PWM control
provides stable switching and cycle-by-cycle
current limiting for superior load and line
response in addition to protection of the internal
main switch and synchronous rectifier. 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 to ramp
the inductor current at each rising edge of the
internal oscillator, then switched off when the
peak inductor current is above the error voltage.
When the main switch is turned off, the
synchronous rectifier is immediately turned on
and stays on until the next cycle begins.
Dropout Operation
The MP2101 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 to deliver current to the output up to the
PFET current limit. The output voltage then
becomes the input voltage minus the voltage
drop across the main switch and the inductor.
MP2101 Rev. 1.0
8/18/2006
Short Circuit Protection
When the output is shorted to ground, the
oscillator frequency is reduced to prevent the
inductor current from increasing beyond the
PFET current limit, which 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.
Maximum Load Current
The MP2101 can operate down to a 2.5V input
voltage. However the maximum load current
decreases at lower inputs due to a 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.
Power OK
The MP2101 provides an open-drain PWROK
output that goes high after both channels reach
regulation during startup. PWROK goes low
after one of the output channels goes out of
regulation by ±10% or when the device enters
shutdown. There is a built-in deglitch timer to
avoid a false PWROK trigger during load
transients (50µs for the switcher and 150µs for
the LDO). When the output is disabled, Power
OK remains low.
200mA Linear Regulator
The 200mA low dropout (LDO) linear regulator
has separate input (IN2) and output (OUT2)
pins for the internal power device. The control
circuitry of the LDO takes power from the main
input supply (IN1). Both IN1 and IN2 input
supplies must be present for the LDO to work
properly. The LDO power device input (IN2) can
be connected to the switcher output or directly
to the main supply (Figure 2). If IN2 is tied to
IN1, an optional RC filter can be inserted
between IN1 and IN2. The RC filter reduces
switching noise coupling from IN1 to IN2 and
power dissipation inside the MP2101. The
switcher guarantees 800mA output current, but
output current to the switcher load will be
reduced if the LDO draws current from the
switcher output.
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8
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
APPLICATION INFORMATION
Output Voltage Setting
The external resistor divider sets the output
voltage. The feedback resistor R1 of the switcher
also sets the feedback loop bandwidth with the
internal compensation capacitor (see Figure 1).
R1 of the switcher should be 300kΩ for optimal
transient response. R2 is then given by:
R2 =
R1
Inductor Selection
A 1µH to 10µH inductor with a DC current rating
of at least 25% higher than the maximum load
current is recommended for most applications.
For best efficiency, the inductor DC resistance
should be <200mΩ. See Table 2 for
recommended inductors and manufacturers.
For most designs, the inductance value can be
derived from the following equation:
VOUT1
−1
0 .6 V
L=
R4 of the LDO should be 60kΩ for good loop
response. R3 is then given by:
R3 = R4 × (
VOUT2
− 1)
0. 6 V
Table 1—Resistor Selection vs. Output
Voltage Setting
VOUT × (VIN − VOUT )
VIN × ∆IL × fOSC
Where ∆IL is inductor ripple current.
Choose the inductor ripple current to be
approximately 30% of the maximum load
current (800mA).
The maximum inductor peak current is:
IL(MAX ) = ILOAD +
VOUT
R1
R2
R3
R4
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%)
60kΩ
(1%)
90kΩ
(1%)
120kΩ
(1%)
190kΩ
(1%)
60kΩ
(1%)
60kΩ
(1%)
60kΩ
(1%)
60kΩ
(1%)
∆IL
2
Under light load conditions below 100mA, larger
inductance is recommended for improved
efficiency. Table 3 lists inductors recommended
for this purpose.
Table 2—Suggested Surface Mount Inductors
Manufacturer
Part Number
Inductance (µH)
Max DCR (Ω)
Saturation
Current (A)
Dimensions
LxWxH (mm3)
Sumida
Toko
Sumida
CDRH2D11
D521C
CDRH3D16
2.2
2.2
2.2
0.098
0.059
0.072
1.27
1.63
1.20
3.2 x 3.2 x 1.2
5 x 5 x 1.5
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
MP2101 Rev. 1.0
8/18/2006
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TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
Switcher Input Capacitor Selection
The input capacitor (CIN1) reduces the surge
current drawn from the input and switching
noise from the device. The input capacitor
impedance at the switching frequency should
be less than the 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.
Switcher Output Capacitor Selection
The output capacitor (CO1) keeps the output
voltage ripple small and ensures regulation loop
stability. The output capacitor impedance
should be low at the switching frequency.
Ceramic capacitors with X5R or X7R dielectrics
are recommended. The output ripple ∆VOUT is
approximately:
∆VOUT1
× (VIN1 − VOUT1 )
V
≤ OUT1
×
VIN1 × f OSC × L
⎛
⎞
1
⎜ ESR +
⎟
⎜
8 × fOSC × C O1 ⎟⎠
⎝
Thermal Dissipation
Power dissipation should be considered when
both channels of the MP2101 provide maximum
output current at high ambient temperatures. If
the junction temperature rises above 150°C, the
two channels will shut down.
Start-Up Consideration
To ensure a smooth start-up of OUT1 and
OUT2, it is recommended that the enable
signals (EN1 and EN2) be asserted only after
the input power rails have been stabilized. If
EN1 and EN2 are tied to input rails directly, the
UVLO of the MP2101 will dictate when the part
starts switching. Since for certain systems, the
input supply may have relatively high
impedance during ramp up, therefore
depending solely on UVLO to start the part may
cause input rail dip and output bounce. If the
system designer can not provide the enable
signal after input power rail is fully established,
it is recommended that EN1 and EN2 are
connected to the input power rail through a RC
delay network (as shown in Figure 2). The RC
time constant needs to be significantly large
compare to the ramp-up time of the input power
rail, which is usually of a few ms.
PC Board Layout
The high current paths (GND, IN1/IN2 and
SW1) 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 should be
placed next to the FB pins. Keep the switching
nodes SW1 short and away from the feedback
network.
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 MP2101 is operating in a 70°C
ambient temperature environment.
PD MAX =
MP2101 Rev. 1.0
8/18/2006
150 o C − 70 o C
50 o C / W
= 1 .6 W
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MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
10
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
TYPICAL APPLICATION CIRCUIT
OPTIONAL
VIN
3.3V - 6V
2
OPTIONAL RIN3
OUT1
1.8V @ 800mA
CIN3
3
4
6
1
EN1
IN1
SW1
EN2
PWROK
MP2101
OUT2
IN2
FB2
FB1
GND
9
POWER OK
8
7
10
OUT2
2.5V @ 200mA
5
Figure 2—Optional RC Delay on EN1 and EN2 Circuit
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
11
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
PACKAGE INFORMATION
3mm x 3mm QFN10
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.
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
12