
2002 Microchip Technology Inc.
DS21372B-page 1
TC125/TC126
Features
Assured Start-up at 0.9V
PFM (100kHz Max Operating Frequency)
40
μ
A Maximum Supply Current
(V
OUT
= 3V @ 30mA)
0.5
μ
A Shutdown Mode (TC125)
Voltage Sense Input (TC126)
Requires Only Three External Components
80mA Maximum Output Current
Small Package: 5-Pin SOT-23A
Applications
Palmtops/PDAs
Battery-Operated Systems
Cameras
Portable Communicators
Device Selection Table
*Other
Microchip Technology Inc. for details.
output
voltages
are
available.
Please
contact
Package Type
General Description
The TC125/126 step-up (Boost) switching regulators
furnish output currents to a maximum of 80mA
(V
IN
= 2V, V
OUT
= 3V) with typical efficiencies above
80%. These devices employ pulse frequency modula-
tion (PFM) for minimum supply current at low loads.
They
are
ideal
for
battery-operated
powered from one or more cells.
current is less than 70
μ
A at full output load, and less
than 5
μ
A in standby (V
OUT
= 3V). Both devices require
only an external inductor, diode, and capacitor to
implement a complete DC/DC regulator.
applications
Maximum supply
The TC126 has separate output voltage sensing and
chip power inputs for greater application flexibility. The
TC125 combines the output voltage sensing and chip
power inputs onto a single package pin, but adds a
power-saving shutdown mode that suspends regulator
operation and reduces supply current to less than
0.5
μ
A when the shutdown control input (SHDN) is low.
The TC125/TC126 are available in a small 5-Pin
SOT-23A package, occupy minimum board space and
use small external components. The TC125 accepts
input voltages from 2V to 10V. The TC126 accepts
input voltages from 2.2V to 10V. Both the TC125 and
TC126 have a start-up voltage of 0.9V at light load.
Typical Application
Part
Number
Output
Voltage
(V)*
Package
Operating
Temp.
Range
TC125501ECT
TC125331ECT
TC125301ECT
TC126503ECT
TC126333ECT
TC126303ECT
5.0
3.3
3.0
5.0
3.3
3.0
5-Pin SOT-23A
5-Pin SOT-23A
5-Pin SOT-23A
5-Pin SOT-23A
5-Pin SOT-23A
5-Pin SOT-23A
-40
°
C to +85
°
C
-40
°
C to +85
°
C
-40
°
C to +85
°
C
-40
°
C to +85
°
C
-40
°
C to +85
°
C
-40
°
C to +85
°
C
5-Pin SOT-23A
NOTE:
5-Pin SOT-23A is equivalent to the EIAJ SC-74A
V
DD
SENSE
TC125
1
2
3
5
4
PS
LX
GND
NC
SHDN
TC126
1
2
3
5
4
LX
GND
NC
3V
2 x "AA"
Cell
+
–
Two Cell to 5V Boost Regulator
1
2
3
5
4
TC125
LX
SHDN
NC
PS
GND
MA735
+
V
IN
Sumida
100
H CD54
V
5V @80mA
47
F/16V
Tantalum
PFM Step-Up DC/DC Regulators