LQH4C100K04 [MPS]
1.6MHz Synchronous Step-Down plus 200mA LDO; 为1.6MHz同步降压型加200毫安LDO
| 型号： | LQH4C100K04 |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | 1.6MHz Synchronous Step-Down plus 200mA LDO |
| 文件： | 总12页 (文件大小：469K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TM
MP2101
1.6MHz Synchronous Step-Down
plus 200mA LDO
TM
The Future of Analog IC Technology
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.
•
•
•
•
•
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
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.
Power On Reset Output
Available in 3x3 10-Pin QFN Packages
APPLICATIONS
•
•
•
•
•
DVD+/-RW Drives
Smart Phones
PDAs
Digital Cameras
Portable Instruments
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.
“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
V
=3.3V
POWER OK
IN
90
80
70
60
50
40
2
3
4
6
1
9
OFF ON
EN1
IN1
EN2
8
V
IN
PWROK
L1
2.5V - 6V
7
OUT2
1.2V @ 200mA
SW1
IN2
OUT2
FB2
MP2101
V
=4.2V
IN
OUT1
10
5
1.8V @ 600mA
FB1
GND
V
=5.0V
IN
10
100
1000
LOAD CURRENT (mA)
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
1
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
PACKAGE REFERENCE
ABSOLUTE MAXIMUM RATINGS (1)
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
TOP VIEW
FB1
EN1
IN1
1
2
3
4
5
10 FB2
9
8
7
6
EN2
PWROK
OUT2
IN2
SW1
GND
Recommended Operating Conditions (2)
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 (3)
θJA
θJC
QFN10 (3mm x 3mm).............50...... 12... °C/W
Part Number*
Package
Temperature
QFN10
(3mm x 3mm)
Notes:
MP2101DQ
–40°C to +85°C
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
For Tape & Reel, add suffix –Z (eg. MP2101DQ–Z)
For RoHS compliant packaging, add suffix –LF (eg.
MP2101DQ–LF–Z)
*
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
Min
Typ
400
80
Max Units
VFB1/2 = 0.62V
550
100
400
1
µA
µA
µA
µA
°C
%
No Load Supply Current
VEN1 = 0V, VEN2 = 3.6V
VEN1 = 3.6V, VEN2 = 0V
VEN1/2 = 0V, VIN1/2 = 6V
Hysteresis = 20°C
300
0.01
150
10
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
FB1/2 with respect to the Nominal Value
FB1/2 with respect to the Nominal Value
ISINK = 5mA
–10
%
0.3
1.5
2.5
V
Switching Regulator
LDO
50
µs
150
0.96
900
–40°C ≤ TA ≤ +85°C
0.3
1.5
V
EN1/2 Pull-Down Resistor
Switching Regulator
kΩ
IN1 Under Voltage Lockout Threshold Rising Edge
IN1 Under Voltage Lockout Hysteresis
2.0
V
100
mV
TA = +25°C
0.588 0.600 0.612
Regulated FB1Voltage
V
–40°C ≤ TA ≤ +85°C
VFB1 = 0.62V
0.582
–50
0.618
+50
FB1 Input Bias Current
–2
nA
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
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
Condition
Min
Typ
0.35
0.25
Max Units
SW1 PFET On Resistance
SW1 NFET On Resistance
ISW1 = 100mA
ISW1 = –100mA
Ω
Ω
V
V
EN1 = 0V, VIN = 6V
SW1 = 0V or 6V
SW1 Leakage Current
–2
+2
µA
Duty Cycle = 100%,
Current Pulse Width < 1ms
SW1 PFET Peak Current Limit
0.9
1.2
1.4
1.6
2.0
2.0
A
Oscillator Frequency
Linear Regulator LDO
IN2 Input Range
MHz
ILOAD = 10mA, VOUT2=VFB2
TA = +25°C
1.2
VIN1
V
V
0.588 0.600 0.612
Regulated FB2 Voltage
–40°C ≤ TA ≤ +85°C
VFB2 = 0.6V
0.582
–50
0.618
+50
FB2 Input Bias Current
OUT2 Short Circuit Foldback
OUT2 Output Current
Dropout Voltage (5)
Notes:
–2
nA
mA
mA
mV
VOUT2 = 0V
180
VOUT = 1.2V
200
ILOAD = 150mA, VOUT2 = 1.2V
280
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 Description
1
2
FB1
EN1
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
regulator.
3
IN1
4
5
6
SW1
GND
IN2
Switcher Switch Node. Output for the 800mA switcher channel.
Ground.
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
minimum 1µF ceramic capacitor at 200mA of load current.
7
OUT2
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%
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.
8
PWROK
Enable 2. Enable input for the linear regulator LDO. Pull high to turn on the LDO; low to turn it
off.
9
EN2
FB2
10
Feedback 2. Feedback input for the linear regulator output (OUT2).
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
3
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
Efficiency vs
Load Current
Efficiency vs
Load Current
90
80
70
60
50
40
30
20
10
95
85
75
65
55
45
35
25
95
85
75
65
55
45
35
25
V
=3.3V
IN
V
=4.2V
V
=3.3V
IN
IN
V
=4.2V
IN
V
=5.0V
IN
V
=4.2V
IN
V
=5.0V
IN
V
=5.0V
IN
10
100
1000
10
100
LOAD CURRENT (mA)
1000
10
100
LOAD CURRENT (mA)
1000
LOAD CURRENT (mA)
Efficiency vs
Load Current
Efficiency vs
Load Current
Efficiency vs
Load Current
95
85
75
65
55
45
35
25
100
90
80
70
60
50
40
100
90
80
70
60
50
40
30
V
=3.3V
IN
V
=3.3V
IN
V
=4.2V
IN
V
=4.2V
IN
V
=5.0V
IN
V
=4.2V
IN
V
=5.0V
IN
V
=5.0V
IN
10
100
1000
10
100
1000
10
100
LOAD CURRENT (mA)
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
Output Voltage vs
Load Current
Output Voltage vs
Load Current
Output Voltage vs
Load Current
1.82
1.81
1.80
1.79
1.78
1.77
1.76
2.52
2.50
2.48
2.46
2.44
2.42
2.40
3.33
3.32
3.31
3.30
3.29
3.28
3.27
3.26
3.25
V
=4.2V
IN
V
=3.3V
V
=4.2V
IN
IN
V
=4.2V
IN
V
=5.0V
IN
V
=3.3V
IN
V
=5.0V
IN
V
=5.0V
IN
0
200 400 600 800 1000
LOAD CURRENT (mA)
0
200 400 600 800 1000
LOAD CURRENT (mA)
0
200 400 600 800 1000
LOAD CURRENT (mA)
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
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
Output Voltage vs
Load Current
Output Voltage vs
Load Current
V
= 1.5V
V
= 2.5V
OUT2
OUT2
1.56
1.54
1.52
1.50
1.48
2.53
2.52
2.51
2.50
2.49
1.206
1.205
1.204
1.203
1.202
V
=3.3V
IN
V
=3.3V
IN
V
=1.8V
80
IN
LDO
LDO
LDO
0
40
80
120 160 200
0
40
80
120 160 200
0
40
120 160 200
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
PSRR vs
Frequency
Frequency vs
Input Voltage
Feedback Voltage vs
Temperature
100
90
80
70
60
50
40
30
20
10
0
1.8
1.7
1.6
1.5
1.4
1.3
0.62
0.61
0.60
0.59
0.58
FB2
FB1
10
100
1K
10K 100K 1M
4.0
4.4
4.8
5.2
5.6
6.0
-40 -10 +20 +50 +80 +110 +140
FREQUENCY (Hz)
INPUT VOLTAGE (V)
TEMPERATURE (°C)
Enable Turn On
Enable Turn Off
LDO Dropout vs
Load Current
EN = 3.6V, I
= 0.3A,
= 0.1A Resistive Load
EN = 3.6V, I
= 0.3A,
OUT1
OUT1
= 0.1A Resistive Load
I
I
OUT2
OUT2
0.5
0.4
0.3
0.2
0.1
0.0
EN
5V/div.
EN
2V/div.
PWROK
PWROK
5V/div.
2V/div.
V
OUT1
1V/div.
V
OUT1
1V/div.
V
OUT2
1V/div.
V
OUT2
1V/div.
0
50
100 150 200 250
LOAD CURRENT (mA)
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
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
Heavy Load Ripple
EN = 4V, I
= 0.3A,
= 0.1A Resistive Load
EN = 4V, I
= 0.3A,
= 0.1A Resistive Load
EN1 = V = 5V,
IN
OUT1
OUT1
I
I
OUT2
I
= 0.8A Resistive Load
OUT2
OUT1
V
OUT1
10mV/div.
V
IN
2V/div.
V
IN
2V/div.
V
SW
2V/div.
V
V
OUT1
OUT1
2V/div.
1V/div.
I
L
0.5A/div.
V
V
OUT2
OUT2
1V/div.
1V/div.
1ms/div.
400ns/div.
PWROK Off vs
Shorted
PWROK Off vs
V Shorted
OUT2
Over Current Protection
I
= 0.3A Resistive Load
V
OUT1
OUT1
EN = 4V, I
= 0.3A,
EN = 4V, I
= 0.3A,
OUT1
= 0.1A Resistive Load
OUT1
= 0.1A Resistive Load
I
I
OUT2
OUT2
V
OUT1
2V/div.
SW
5V/div.
PWROK
2V/div.
V
PWROK
2V/div.
V
OUT1
1V/div.
V
OUT1
1V/div.
V
OUT2
1V/div.
I
V
L
OUT2
0.5A/div.
1V/div.
LDO Over Current
Protection
Switcher Load Transient
LDO Load Transients
I
= 0.8A Resistive Load
V
I
= 3.3V, V
= 1.2V,
= 0.02A to 0.15A Resistive Load
OUT1
IN2 OUT2
V
= 3.3V, V
= 2.5V
OUT2
IN2
OUT2
V
V
OUT1
OUT2
V
0.1V/div.
50mV/div.
OUT2
1V/div.
I
I
OUT2
OUT2
I
L
0.1A/div.
0.1A/div.
0.5A/div.
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
6
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
OPERATION
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.
The MP2101 uses an external resistor divider to
set both the switcher and LDO output voltage
from 0.6V to 6V.
IN1
3
+
BIAS
&
IAMP
10X
EN1/2
2/9
VOLTAGE
REFERENCE
--
CURRENT
SENSE
AMP
ICS
SLOPE COMP
EAO1
0.6V
+
+
--
PWM
OSC
DH
+
PWMCMP
FEEDBACK
MAIN
ERROR EAMP1
SWITCH
(PCH)
AMP
FB1
--
1
PWM
CONTROL
LOGIC
4
SW1
SYNCHRONOUS
RECTIFIER
(NCH)
1.6MHz
CC
17pF
OSCILLATOR
DL
5
6
GND
IN2
+
FB2
10
EAO2
EAMP2
--
0.6V
7
8
OUT2
FB1/2
+
--
OUT_Hi
PWROK
0.66V
0.54V
NO
GOOD
POWER ON RESET
WINDOW
COMPARATORS
+
--
OUT_Lo
Figure 1—MP2101 Function Diagram
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
7
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
Short Circuit Protection
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.
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.
This switcher can achieve 100% duty cycle.
The duty cycle (D) of a step-down switcher is
defined as:
VOUT
D = TON × fOSC ×100% ≈
×100%
Maximum Load Current
VIN
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.
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.
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.
Dropout Operation
200mA Linear Regulator
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.
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.
MP2101 Rev. 1.0
8/18/2006
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2006 MPS. All Rights Reserved.
8
TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
APPLICATION INFORMATION
Output Voltage Setting
Inductor Selection
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).
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 <200mꢀ. See Table
2
for
R1 of the switcher should be 300kꢀ for optimal
transient response. R2 is then given by:
recommended inductors and manufacturers.
For most designs, the inductance value can be
derived from the following equation:
R1
R2 =
VOUT1
VOUT
×
(
V
− VOUT
)
IN
− 1
L =
0.6V
V × ∆IL × fOSC
IN
R4 of the LDO should be 60kꢀ for good loop
Where ∆IL is inductor ripple current.
response. R3 is then given by:
Choose the inductor ripple current to be
approximately 30% of the maximum load
current (800mA).
VOUT2
R3 = R4× (
−1)
0.6V
The maximum inductor peak current is:
Table 1—Resistor Selection vs. Output
Voltage Setting
∆IL
IL(MAX) = ILOAD
+
2
VOUT
R1
R2
R3
R4
Under light load conditions below 100mA, larger
inductance is recommended for improved
efficiency. Table 3 lists inductors recommended
for this purpose.
60kꢀ
(1%)
60kꢀ
300kꢀ
(1%)
300kꢀ
(1%)
1.2V
(1%)
90kꢀ
(1%)
60kꢀ
300kꢀ
200kꢀ
1.5V
1.8V
2.5V
(1%)
(1%)
(1%)
120kꢀ
(1%)
60kꢀ
300kꢀ
(1%)
150kꢀ
(1%)
(1%)
190kꢀ
(1%)
60kꢀ
300kꢀ
(1%)
95.3kꢀ
(1%)
(1%)
Table 2—Suggested Surface Mount Inductors
Saturation
Current (A)
Dimensions
Manufacturer
Sumida
Part Number
CDRH2D11
D521C
Inductance (µH) Max DCR (Ω)
LxWxH (mm3)
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
Toko
Sumida
CDRH3D16
Table 3—Inductors for Improved Efficiency at 25mA, 50mA, under 100mA Load.
Saturation
Manufacturer
Part Number
DO1605T-103MX
LQH4C100K04
CR32-100
Inductance (µH) Max DCR (Ω)
Current (A)
IRMS (A)
Coilcraft
Murata
Sumida
Sumida
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
CR54-100
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
Start-Up Consideration
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
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.
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:
PC Board Layout
VOUT1
×
(
VIN1 − VOUT1
)
×
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.
∆VOUT1
≤
VIN1 × fOSC ×L
⎛
⎞
⎟
⎟
⎠
1
⎜
ESR +
⎜
⎝
8× fOSC × CO1
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.
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.
150o C − 70o C
PDMAX
=
= 1.6W
50o C / W
MP2101 Rev. 1.0
8/18/2006
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TM
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
TYPICAL APPLICATION CIRCUIT
OPTIONAL
V
IN
3.3V - 6V
POWER OK
2
3
4
6
1
9
EN1
IN1
EN2
PWROK
OUT2
C
R
IN3
8
OPTIONAL
IN3
7
OUT1
1.8V @ 800mA
OUT2
2.5V @ 200mA
SW1
IN2
MP2101
10
5
FB2
FB1
GND
Figure 2—Optional RC Delay on EN1 and EN2 Circuit
MP2101 Rev. 1.0
8/18/2006
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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
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