TC1682 datasheet(4/10 Pages) MICROCHIP

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TC1682/TC1683/TC1684

DS21537B-page 4

 2002 Microchip Technology Inc.

3.0

DETAILED DESCRIPTION

The TC1682/TC1683/TC1684 inverting charge pump

converters perform a -2x multiplication of the voltage

applied to the VIN pin. Conversion is performed using

two synchronous switching matrices and three external

capacitors. When the shutdown input is held at a logic

high, the device goes into a very low power mode of

operation consuming less than 1

µA of supply current.

Figure 3-1 is a block diagram representation of the

TC1682/TC1683/TC1684 architecture. The first switch-

ing stage inverts the voltage present at VIN and the

second stage uses the ‘-VIN’ 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 TC1682 synchronously

switches

12kHz,

the

TC1683

synchronously

switches at 35kHz, and the TC1684 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

supply

current

(see

Section 1.0

Electrical

Characteristics).

When the shutdown input is in a high state, the

oscillator and both switch matrices are powered off

placing the TC1682/TC1683/TC1684 in the shutdown

mode. When the VIN 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:

TC1682/TC1683/TC1684 ARCHITECTURE

SHDN

ENABLE

VOUT = -2VIN

-VIN

COUT

VIN

Switch Matrix

(1st Stage)

Switch Matrix

(2nd Stage)

Oscillator

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