TC3682_05 Datasheet, PDF (4/10 Pages) Microchip Technology – Inverting Charge Pump Voltage Doublers with Active Low Shutdown

TC3682/TC3683/TC3684
3.0 DETAILED DESCRIPTION
The TC3682/TC3683/TC3684 inverting charge pumps
perform a -2x multiplication of the voltage applied to
the V_IN pin. Conversion is performed using two
synchronous switching matrices and three external
capacitors. When the shutdown input is held at a logic
low, the device goes into a very low power mode of
operation consuming less than 1μA of supply current.
Figure 3-1 is a block diagram representation of the
TC3682/TC3683/TC3684 architecture. The first switch-
ing stage inverts the voltage present at V_IN and the
second stage uses the ‘-V_IN’ output generated from the
first stage to produce the ‘-2X’ output function from the
second stage switching matrix.
Each device contains an on-board oscillator that
synchronously controls the operation of the charge
pump switching matrices. The TC3682 synchronously
switches at 12kHz, the TC3683 synchronously
switches at 35kHz, and the TC3684 synchronously
switches at 125kHz. The different oscillator frequencies
for this device family allow the user to trade-off
capacitor size versus supply current. Faster oscillators
can use smaller external capacitors, but will consume
more supply current (see Section 1.0 Electrical
Characteristics).
When the shutdown input is in a low state, the oscillator
and both switch matrices are powered off placing the
TC3682/TC3683/TC3684 in the shutdown mode.
When the V_IN supply input is powered from an external
battery, the shutdown mode minimizes power
consumption, which in turn will extend the life of the
battery.
FIGURE 3-1:
TC3682/TC3683/TC3684 ARCHITECTURE
V_IN
+
C1
Oscillator
ENABLE
Switch Matrix
(1st Stage)
ENABLE
-V_IN
C_OUT1
+
SHDN
+
C2
Switch Matrix
(2nd Stage)
ENABLE
-2V_IN
C_OUT2
+
DS21556C-page 4
© 2005 Microchip Technology Inc.