LTC1928-5_15 Datasheet, PDF (1/8 Pages) Linear Technology – Doubler Charge Pump with Low Noise Linear Regulator in ThinSOT

LTC1928-5
Doubler Charge Pump with
Low Noise Linear Regulator
in ThinSOT
FEATURES
s _{Low Output Noise: 90µVRMS (100kHz BW)}
s _{Fixed Output Voltage: 5V}
s _{Input Voltage Range: 2.7V to 4.4V}
s _{No Inductors Required}
s _{Uses Small Ceramic Capacitors}
s _{Output Current Up to 30mA}
s _{550kHz Switching Frequency}
s _{Low Operating Current: 190µA}
s _{Low Shutdown Current: 4µA}
s _{Internal Thermal Shutdown and Current Limiting}
s _{Low Profile (1mm) ThinSOT}^TM _Package
U
APPLICATIO S
s _{VCO Power Supplies for Cellular Phones}
s _{2-Way Pagers}
s _{Wireless PCMCIA Cards}
s _{Portable Medical Instruments}
s _{Low Power Data Acquisition}
s _{Remote Transmitters}
s _{White LED Drivers}
s _{GaAs Switches}
DESCRIPTIO
The LTC^®1928-5 is a doubler charge pump with an internal
low noise, low dropout (LDO) linear regulator. The part is
designed to provide a low noise boosted supply voltage for
powering noise sensitive devices such as high frequency
VCOs in wireless applications.
An internal charge pump converts a 2.7V to 4.4V input to
a boosted output, while the internal LDO regulator con-
verts the boosted voltage to a low noise regulated output.
The regulator is capable of supplying up to 30mA of output
current. Shutdown reduces the supply current to < 8µA,
removes the load from V_IN by disabling the regulator and
discharges V_OUT to ground through a 200Ω switch.
The LTC1928-5 LDO regulator is stable with only 2µF on
the output. Small ceramic capacitors can be used, reduc-
ing PC board area.
The LTC1928-5 is short-circuit and overtemperature pro-
tected. The part is available in a 6-pin low profile
(1mm)ThinSOT package.
, LTC and LT are registered trademarks of Linear Technology Corporation
ThinSOT is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
Output Noise (BW = 10Hz to 2.5MHz)
V_IN
2.7V TO 4.4V
4.7µF
0.47µF
LTC1928-5
1 _VIN
3
V_OUT
5 _CP
4
CPO
6 _{CN/SHDN GND} 2
5V
V_OUT
4.7µF
4.7µF
19285 F01
Figure 1. Low Noise 5V Power Supply
V_OUT
200µV/DIV
C_CPO = C_OUT = 4.7µF
I_OUT = 10mA
V_IN = 3V
V_OUT = 5V
T_A = 25°C
100µs/DIV
19285 TA01
1