MIC2141
Micrel
MIC2141
Micropower Boost Converter
Preliminary Information
General Description
The MIC2141 is a micropower boost switching regulator that
can operate from 3- or 4-cell nickel-metal-hydride batteries or
a single Li-ion cell. This regulator employs a constant 330kHz,
fixed 18% duty-cycle, gated-oscillator architecture.
The MIC2141 can be used in applications where the output
voltage must be dynamically adjusted. The device features a
control signal input which is used to proportionally adjust the
output voltage. The control signal input has a gain of 6,
allowing a 0.8V to 3.6V control signal to vary a 4.8V to 22V
output.
The MIC2141 requires only three external components to
operate and is available in a tiny 5-lead SOT-23 package for
space and power-sensitive portable applications. The
MIC2141 draws only 70µA of quiescent current and can
operate with an efficiency exceeding 85%.
Features
•
•
•
•
•
•
•
•
Implements low-power boost, SEPIC, or flyback
2.5V to 14V input voltage
330kHz switching frequency
<2µA shutdown current
70µA quiescent current
1.24V bandgap reference
typical output current 1mA to 10mA
SOT-23-5 Package
Applications
• LCD bias supply
• CCD digital camera supply
Ordering Information
Part Number
MIC2141-BM5
Junction Temp. Range
–40°C to +85°C
Package
SOT-23-5
Typical Application
10µH
V
C
*
(from DAC)
MIC2141
V
C
(V)
1
2
3
4
5
Control Voltage
vs. Output Voltage
Variable
V
OUT
4.0
3.5
3.0
2.5
2.0
1.5
1.0
10µF
0.5
0
0
5
10
15
V
OUT
(V)
20
25
DAC-Controlled LCD Bias Voltage Supply
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
June 2000
1
MIC2141
MIC2141
Micrel
Pin Configuration
SW GND IN
3
2
1
SAxx
4
5
Part
Identification
FB
VC
SOT-23-5 (BM)
Pin Description
Pin Number
1
2
3
4
5
Pin Name
IN
GND
SW
FB
VC
Pin Function
Input: +2.5V to +14V supply for internal circuity.
Ground: Return for internal circuitry and internal MOSFET (switch) source.
Switch Node (Input): Internal MOSFET drain; 22V maximum.
Feedback (Input): Output voltage sense node. Compared to V
C
control
input voltage.
Control (Input): Output voltage control signal input. Input voltage of 0.8V to
3.6V is proportional to 4.8V to 22V output voltage (gain of 6). If the pin is not
connected, the output voltage will be V
IN
– 0.5V.
MIC2141
2
June 2000
MIC2141
Micrel
Absolute Maximum Ratings (Note 1)
Supply Voltage (V
IN
) ................................................... +18V
Switch Voltage (V
SW
) .................................................. +24V
Feedback Voltage (F
B
) ................................................ +24V
Control Input Voltage (V
C
),
Note 3 ..
V
IN
–200mV
≤
V
C
≤
4V
ESD Rating,
Note 4 ......................................................
2kV
Operating Ratings (Note 2)
Supply Voltage (V
IN
) .................................... +2.5V to +14V
Switch Voltage (V
SW
) ...................................... +3V to +22V
Ambient Temperature (T
A
) ......................... –40°C to +85°C
Junction Tempgserature (T
J
) ................... –40°C to +125°C
Package Thermal Resistance
SOT-23-5 (θ
JA
) ...................................................... 220°C/W
Electrical Characteristics
V
IN
= 3.6V, V
OUT
= 5V; I
OUT
= 1mA; T
J
= 25°C, bold values indicate –40°C
≤
T
A
≤
+85°C; unless noted.
Parameter
Input Voltage
Quiescent Current
Comparator Hysteresis
Control Voltage Gain (V
OUT
/V
C
)
Controlled Output Voltage,
Note 3
2.5V
≤
V
IN
≤
12V, V
OUT
= 15V
V
C
= 0.8V; 2.5V
≤
V
IN
≤
4.2V
V
C
= 2.5V; 2.7V
≤
V
IN
≤
12V
V
C
= 3.4V; 3.6V
≤
V
IN
≤
12V
Load Regulation
Line Regulation
Switch On-Resistance
100µA
≤
I
OUT
≤
1mA, V
OUT
= 15V
2.5V
≤
V
IN
≤
12V; I
OUT
≤
1mA
I
SW
= 100mA, V
IN
= 3.6V
I
SW
= 100mA, V
IN
= 12V
Oscillator Frequency
Oscillator Duty Cycle
Note 1.
Note 2.
Note 3.
Note 4.
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
V
C
= 4V sets V
OUT
to 24V (absolute maximum level on V
SW
); V
C
must be
≤
V
IN
– 200mV.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Condition
Min
2.5
Typ
Max
14
Units
V
µA
mV
Switch off, V
IN
= 3.6V
70
10
6
4.85
14.55
19.4
5.0
15.0
20.0
0.25
0.05
4
2.5
300
15
330
18
100
5.15
15.45
20.6
1
0.2
V
V
V
%
%/V
Ω
Ω
360
kHz
%
June 2000
3
MIC2141
MIC2141
Micrel
Typical Characteristcs
Feedback Current
vs. Output Voltage
25
FEEDBACK CURRENT (µA)
20
15
10
5
0
0
OUTPUT VOLTAGE (V)
20
V
IN
= 5V
L = 33µH
V
IN
= 2.5V
10
Control Voltage
vs. Output Voltage
6.4
6.3
6.2
GAIN
6.1
6.0
5.9
V
IN
= 3.6V
5.8
4
5.7
0
Gain
vs. Output Voltage
V
IN
= 5V
L = 33µH
15
5
5
10
15
20
OUTPUT VOLTAGE (V)
25
0
0
1
2
3
CONTROL VOLTAGE (V)
5
10
15
20
OUTPUT VOLTAGE (V)
25
Control Current
vs. Control Voltage
7
CONTROL CURRENT (nA)
OUTPUT VOLTAGE (V)
6
5
4
3
2
1
0
0
1
2
3
CONTROL VOLTAGE (V)
4
15.00
Load Regulation
15.0
I
PEAK
= 100mA
L = 33µH
OUTPUT VOLTAGE (V)
14.8
14.6
14.4
14.2
14.0
2
Line Regulation
14.95
14.90
I
PEAK
= 150mA
L = 22µH
14.85
V
IN
= 5V
14.80
0
1
2
3
4
LOAD CURRENT (mA)
5
L = 33µH
I
L
= 100µA
4
6
8
10
INPUT VOLTAGE (V)
12
Oscillator Frequency
vs. Input Voltage
400
QUIESCENT CURRENT (µA)
380
360
340
320
300
2
280
240
Quiescent Current
vs. Input Voltage
0.60
0.58
ON-TIME (µs)
200
160
120
80
40
0
0
2
4 6 8 10 12 14 16
INPUT VOLTAGE (V)
0.56
0.54
0.52
On-Time
vs. Temperature
FREQUENCY (kHz)
4
6
8 10 12 14
INPUT VOLTAGE (V)
16
0.50
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Frequency
vs. Temperature
350
340
330
320
310
300
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
20
19
DUTY CYCLE (%)
18
17
16
15
14
13
12
Duty Cycle
vs. Temperature
FREQUENCY (kHz)
11
10
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
MIC2141
4
June 2000
MIC2141
Micrel
Quiescent Current
vs. Temperature
88
QUIESCENT CURRENT (µA)
86
84
82
80
78
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
V
IN
= 5V
15.00
14.80
14.60
14.40
14.20
Output Voltage
vs. Temperature
6.00
5.98
V
IN
= 5V
L = 33µH
5.96
5.94
5.92
Gain
vs. Temperature
14.00
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
GAIN
V
IN
= 5V
5.90
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Switch Voltage Drop
vs. Temperature
800
700
600
V
DS
(mV)
500
400
300
200
100
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
V
IN
= 3.3V
I
D
= 100mA
R
DS(on)
(Ω)
8
7
6
Switch On-Resistance
vs. Temperature
900
800
700
V
DS
(mV)
600
500
400
300
200
100
0
2
Switch Voltage Drop
vs. Input Voltage
I
DS
= 100mA
5
4
3
2
1
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
V
IN
= 3.3V
4
6
8
10 12
INPUT VOLTAGE (V)
14
On-Resistance vs.
Input Voltage
9
8
ON-RESISTANCE (Ω)
EFFICIENCY (%)
7
6
5
4
3
2
1
0
2
4
6
8
10 12
INPUT VOLTAGE (V)
14
100
90
80
70
60
50
40
30
20
10
0
0
Efficiency
90
BAT54HT1 Diode
RIPPLE VOLTAGE (mV)
1N4148 Diode
V
IN
= 5V
V
OUT
= 15V
L = 33µH
80
70
60
50
40
30
20
10
0
2
Ripple Voltage vs.
Input Voltage
L = 100µH
V
OUT
= 15V
I
L
= 1mA
1
2
3
OUTPUT CURRENT (mA)
4
4
6
8
10
INPUT VOLTAGE (V)
12
June 2000
5
MIC2141
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