MIC2183_05 Datasheet, PDF (1/12 Pages) Micrel Semiconductor – Low Voltage Synchronous Buck PWM Control IC

MIC2183
Micrel, Inc.
MIC2183
Low Voltage Synchronous Buck PWM Control IC
General Description
Micrel’s MIC2183 is a high efficiency PWM synchronous
buck control IC. With its wide input voltage range of 2.9V to
14V, the MIC2183 can be used to efficiently step voltages
down in 1- or 2-cell Li Ion battery powered applications, as
well as in fixed 3.3V, 5V, or 12V systems.
Efficiencies over 90% are achievable over a wide range of
load conditions with the MIC2183’s PWM control scheme.
The operating frequency can be divided by two by raising the
FREQ/2 pin to V_DD. This allows the user to optimize efficiency
versus board space. It also allows the MIC2183 to be exter-
nally synchronized to frequencies below its nominal 400KHz.
The MIC2183 features an oscillator output, FreqOut, which
can be used to implement a simple charge pump in low
voltage applications. The output of the charge pump can be
fed into the gate drive power circuitry via the V_INP pin. This
feature allows enhanced gate drive, hence higher efficiencies
at low input voltages.
MIC2183 also features a 1µA shutdown mode, and a pro-
grammable undervoltage lockout, making it well-suited for
portable applications.
The MIC2183 is available in 16-pin SOP and QSOP packag-
ing options with a junction temperature range from -40°C to
+125°C.
Features
• Input voltage range: 2.9V to 14V
• >90% efficiency
• Oscillator frequency of 400kHz
• Frequency divide-by-two pin
• Frequency sync to 600kHz
• FreqOut oscillator output allows simple charge pump
implementation in low voltage systems
• Front edge blanking
• 5Ω output drivers (typical)
• Soft start
• PWM current mode control
• 1µA shutdown current
• Cycle-by-cycle current limiting
• Frequency foldback short circuit protection
• Adjustable under-voltage lockout
• 16-pin narrow-body SOP and QSOP package options
Applications
• 3.3V to 2.5V/1.8V/1.5V conversion
• DC power distribution systems
• Wireless modems
• ADSL line cards
• 1-and 2-cell Li Ion battery operated equipment
• Satellite Phones
Typical Application
V_IN = 3.3V
120µF (x2)
6.3V
1 _VINA
16
VINP
7 _EN/UVLO
2 _FreqOut
15 _{FREQ/2 MIC2183}
10 _VDD
4 _COMP
3 _SS
11 _SYNC
SGND
5
CSH ⁹ _1nF
CSL ⁸
OUTP ¹⁴
Si9804DY
(x2)
OUTN ¹³
PGND ¹²
FB ⁶
15mΩ
Si9803DY(x2)
4.7µH
B130
2.5VV^O@^UT5A
220µF (x2)
6.3V
100
95
90
85
80
75
70
65
60
55
500
MIC2183 EFFICIENCY
V_IN = 3.3V
V_OUT = 2.5V
f_S = 200kHz
12345
OUTPUT CURRENT (A)
Adjustable Output Synchronous Buck Converter
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
April 2005
1
M9999-042205