TC1142 Datasheet, PDF (1/12 Pages) Microchip Technology – Inductorless -2x Boost/Buck Regulator

M
TC1142
Inductorless -2x Boost/Buck Regulator
Features
• Input Range 2.5V to 5.5V
• Regulated Output Options from -3.0 to -5.0V
• Output Current 20mA (max)
• 200kHz Internal Oscillator Frequency
• External Synchronizing Clock Input
• Logic Level Shutdown
- 1µA (max) Supply Current
• Available in 8-Pin MSOP Package
Applications
• Cellular Phones
• Battery Powered/Portable Equipment
Device Selection Table
Part
Number
Output
Voltage Package
(V)*
Operating
Temp.
Range
TC1142-3.0EUA 3.0 8-Pin MSOP -40°C to +85°C
TC1142-4.0EUA 4.0 8-Pin MSOP -40°C to +85°C
TC1142-5.0EUA 5.0 8-Pin MSOP -40°C to +85°C
*Other output voltages are available (-3.5V and -4.5V). Please
contact Microchip Technology Inc. for details.
Functional Block Diagram
+
– ^{5.5V to 2.5V}
ON ^OFF
V_IN
CCLK
V_OUT
OSC _{0.47µF C1 TC1142-50}
OVERRIDE
–2x Boost/Buck
V_OUT = -5.0V
4.7µF
C_OUT
0.47µF C2
GND
Package Type
8-Pin MSOP
V_{OUT 1}
C2– 2
C2+ 3
C1– 4
TC1142
8 CCLK
7 V_IN
6 C1+
5 _GND
General Description
The TC1142 generates a regulated negative voltage
from -3V to -5V at 20mA from an input of 2.5V to 5.5V,
using only three external capacitors. Other boost/buck
switching regulators must use an inductor, which is
larger and radiates EMI. An internal voltage
comparator inhibits the charge pump when V_OUT is
more negative than the regulated value (per the
ordering option). The values of flying capacitors C1 and
C2 are chosen to be less than C_OUT in order to reduce
the ripple generated from regulating V_OUT in this
manner. The TC1142 also can be used as a -1x buck
regulator by omitting C2, and connecting the C2 pin to
V_OUT.
The part goes into shutdown when the CCLK input is
driven low. When in shutdown mode, the part draws a
maximum of 1µA. When CCLK is pulled high, the part
runs from the internal 200kHz oscillator. The device
may be run with an external clock, provided the
frequency is greater than 3kHz and less than 500kHz.
The TC1142 comes in a space-saving MSOP package.
+
– ^{5.5V to 3V}
ON ^OFF
V_IN
CCLK
V_OUT
OSC 0.47µF C1 _TC1142-30
OVERRIDE
C2–
GND
–1x Buck
V_OUT = –3.0V
4.7µF
C_OUT
 2002 Microchip Technology Inc.
DS21360B-page 1