Datasheet

TPS60240, TPS60241
TPS60242, TPS60243
SLVS372B – JUNE 2001 – REVISED JANUARY 2002
4
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detailed description
operating principle
The TPS6024x charge pump is a fixed-frequency, dual-phase charge pump that provides 25 mA of continuous
supply current for low-noise applications such as VCOs used in cell phones and wireless appliances.
Low-noise operation results from using a proprietary dual-phase charge pump topology that relies on an
operational amplifier in the feedback loop to reduce ripple. During the first phase, C
1
is charged to the supply
voltage. Terminal C
1+
is connected to V
IN
, and C
1–
is connected to GND. In the second phase, C
1–
is connected
to the output of the operational amplifier, and C
1+
is connected to V
OUT
. The operational amplifier then adjusts
its output until the output V
OUT
delivers the correct voltage to make the resistor divided feedback point equal
to the reference voltage. During this second phase, C
2
is charged to supply voltage. Terminal C
2–
is connected
to GND, and C
2+
is connected to V
IN
. Phase one is then repeated with C
2
, now acting to provide charge to the
output in place of C
1
, which is connected to the supply. The dual-phase operation lowers the output ripple
voltage significantly compared to a standard single-phase charge pump. In addition, the linear feedback of the
operational amplifier eliminates the ripple during discharge of the output capacitor (C
O
).
shutdown
Driving EN low disables the converter. This disables the internal circuits and reduces input current to typically
0.1 µA. In this mode, the load is disconnected from the supply voltage. The device exits shutdown once EN is
set to a high level.
start-up procedure
The converter is enabled when EN is set from logic low to high. The start-up time to reach 90% of the nominal
output voltage is typically 0.5 ms at load currents lower than 10 mA and with an output capacitor of 1 µF.
Increasing the values of C
O
delays the start-up time.
absolute maximum ratings over operating free-air temperature (unless otherwise noted)
†
Supply voltage, V
DD
–0.3 V to 6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power dissipation, P
D
Internally limited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage EN –0.3 V to 6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage C
2–
, C
1–
–0.3 V to V
I
or 5.5 V, whichever is lowest. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Voltage C
2+
, C
1+
–0.3 V to V
I
, V
O,
or 5.5 V, whichever is lowest. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Junction temperature, T
J
125°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature, T
stg
–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shortcircuit output current 80 mA maximum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
†
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
DISSIPATION RATING TABLE
PACKAGE
T
A
≤ 25°C
POWER RATING
DERATING FACTOR
ABOVE T
A
= 25°C
T
A
= 70°C
POWER RATING
T
A
= 85°C
POWER RATING
DGK 376 mW 3.76 mW/°C 207 mW 150 mW
NOTE: The thermal resistance junction to ambient of the DGK package is R
TH–JA
= 150°C/W.