TC1682
TC1683
TC1684
Inverting Charge Pump Voltage Doublers with Active High Shutdown
FEATURES
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Small 8-Pin MSOP Package
Operation from 1.8V to 5.5V
120 Ohms (typ.) Output Resistance
99% Voltage Conversion Efficiency
Only 3 External Capacitors Required
Power-Saving Shutdown Mode
Low Active Supply Current
.......................... 95
µ
A (typ.) for TC1682
..........................225
µ
A (typ.) for TC1683
......................... 700
µ
A (typ.) for TC1684
s
Fully Compatible with 1.8V Logic Systems
GENERAL DESCRIPTION
The TC1682, TC1683 and TC1684 are CMOS charge
pump converters that provide an inverted doubled output
from a single positive supply. An on-board oscillator pro-
vides the clock and only three external capacitors are
required for full circuit implementation. Switching frequen-
cies are 12kHz for the TC1682, 35kHz for the TC1683, and
125kHz for the TC1684. When the SHDN pin is held at a
logic high, the device goes into a very low power mode of
operation consuming less than 1µA (typ.) of supply current.
Low output source impedance (typically 120Ω), pro-
vides output current up to 10mA. The TC1682, TC1683 and
TC1684 feature a 1.8V to 5.5V operating voltage range and
high efficiency, which make them an ideal choice for a wide
variety of applications requiring a negative doubled voltage
derived from a single positive supply (for example: genera-
tion of -7.2V from a +3.6V lithium cell or -10V generated from
a +5V logic supply).The minimum external part count, small
physical size, and shutdown mode feature make this family
of products useful for a wide variety of negative bias power
supply applications.
TYPICAL APPLICATIONS
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LCD Panel Bias
Cellular Phones PA Bias
Pagers
PDAs, Portable Data Loggers
Battery Powered Devices
TYPICAL OPERATING CIRCUIT
ORDERING INFORMATION
Part No.
Package
8-Pin MSOP
8-Pin MSOP
8-Pin MSOP
Osc Freq (kHz) Temp. Range
12
35
125
– 40°C to +85°C
– 40°C to +85°C
– 40°C to +85°C
TC1682EUA
TC1683EUA
TC1684EUA
+
C1
C1+
C1–
V
IN
INPUT
OFF
ON
+
C2
TC1682
SHDN
TC1683
C2+ TC1684
C2–
GND
PIN CONFIGURATION
8-Pin MSOP
V
OUT
V
OUT
= -(2xV
IN
)
C1-
1
C2+
2
C2-
3
V
OUT
4
TC1682
TC1683
TC1684
8
SHDN
7
C1+
6
V
IN
5
GND
– C
OUT
+
Notes:
1) C1 must have a voltage rating greater
than or equal to V
IN
2) C2 and C
OUT
must have a voltage rating greater
than or equal to 2V
IN
2001 Microchip Technology Inc.
DS21537A
TC1682/3/4-1 8/14/00
Inverting Charge Pump Voltage
Doublers with Active High Shutdown
TC1682
TC1683
TC1684
ABSOLUTE MAXIMUM RATINGS*
Input Voltage (V
IN
to GND) ......................... +6.0V, - 0.3V
Output Voltage (V
OUT
to GND)................. -12.0V, + 0.3V
Current at V
OUT
Pin ................................................ 20mA
Short-Circuit Duration V
OUT
to GND ..................Indefinite
Operating Temperature Range ............... 40°C to +85°C
Power Dissipation (T
A
≤
70°C) 8-Pin MSOP ............... 320mW
Storage Temperature (Unbiased) ......... - 65
°C
to +150°C
Lead Temperature (Soldering, 10sec) .................. +260°C
*This is a stress rating only and functional operation of the device at these
or any other conditions above those indicated in the operational sections
of the specifications is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS:
T
A
= -40°C to +85°C, V
IN
= + 5V, C1 = C2 = 3.3µF (TC1682); C1 = C2 =
1µF (TC1683); C1 = C2 = 0.33µF (TC1684); SHDN = GND, unless otherwise noted. Typical values are at T
A
= +25°C
Symbol
I
DD
Parameter
Supply Current
Device
TC1682
TC1683
TC1684
All
All
All
TC1682
TC1683
TC1684
All
All
All
All
TC1682
TC1683
TC1684
Test Conditions
Min
—
—
—
—
1.8
—
8.4
24.5
65
1.4
—
95
—
—
—
—
Typ
95
225
700
0.5
—
—
12
35
125
—
—
99
120
1800
600
200
Max
160
480
1500
2
—
5.5
15.6
45.5
170
—
0.4
—
170
—
—
—
Unit
µA
I
SHDN
V
MIN
V
MAX
F
OSC
Shutdown Supply Current
Minimum Supply Voltage
Maximum Supply Voltage
Oscillator Frequency
SHDN = V
IN
= +5V
R
LOAD
= 1kΩ
R
LOAD
= 1kΩ
µA
V
V
kHz
V
IH
V
IL
V
EFF
R
OUT
T
WK
Shutdown Input
Logic High
Shutdown Input
Logic Low
Voltage Conversion Efficiency
Output Resistance
Wake-Up Time From
Shutdown Mode
V
IN
= V
MIN
to V
MAX
V
IN
= V
MIN
to V
MAX
R
LOAD
=
∞
I
LOAD
= 0.5mA to10mA
R
LOAD
= 2kΩ
V
V
V
Ω
µsec
NOTES:
1. Capacitor contribution is approximately 20% of the output impedance (ESR = 1/pump frequency x capacitance)
PIN DESCRIPTION
Pin No.
1
2
3
4
5
6
7
8
Symbol
C1
–
C2
+
C2
–
V
OUT
GND
V
IN
C1
+
SHDN
Description
C1 Commutation Capacitor Negative Terminal
C2 Commutation Capacitor Positive Terminal
C2 Commutation Capacitor Negative Terminal
Doubling Inverting Charge Pump Output (– 2 x V
IN
)
Ground
Positive Power Supply Input
C1 Commutation Capacitor Positive Terminal
Shutdown Input (Active High)
TC1682/3/4-1 8/14/00
2
2001 Microchip Technology Inc.
DS21537A
Inverting Charge Pump Voltage
Doublers with Active High Shutdown
TC1682
TC1683
TC1684
DETAILED DESCRIPTION
The TC1682, TC1683 and TC1684 inverting charge
pump converters perform a –2x multiplication of the voltage
applied to the V
IN
pin. Conversion is performed using two
synchronous
switching matrices and three external ca-
pacitors. When the shutdown input is held at a logic high,
the device goes into a very low power mode of operation
consuming less than 1uA of supply current.
Figure 1 (below) is a block diagram representation of the
TC1682, TC1683 and TC1684 architecture. The first switch-
ing stage inverts the voltage present at V
IN
and the second
stage uses ‘–V
IN
’ 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 syn-
chronously controls the operation of the charge pump switch-
ing matrices. The TC1682 synchronously switches at 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 oscil-
lators can use smaller external capacitors, but will consume
more supply current (see Electrical Characteristics Table).
When the shutdown input is in a high state, the oscillator
and both switch matrices are powered off placing the TC1682,
TC1683 and TC1684 in the shutdown mode. When the V
IN
supply input is powered from an external battery, the shut-
down mode minimizes power consumption, which in turn will
extend the life of the battery.
APPLICATIONS INFORMATION
Output Voltage Considerations
The TC1682, TC1683 and TC1684 perform inverting
voltage conversions but do not provide any type of regula-
tion. The output voltage will droop in a linear manner with
respect to the output load current. The value of the
equivalent output resistance is approximately 120Ω nominal
at +25°C and V
IN
= +5V. In this particular case, the output
is approximately –10V at very light loads, and will droop
according to the equation below:
V
DROOP
= I
OUT
x R
OUT
Capacitor Selection
In order to maintain the lowest output resistance and
output ripple voltage, it is recommended that low ESR
capacitors be used. Additionally, larger values of C1 and C2
will lower the output resistance and larger values of C
OUT
will
reduce output ripple.
NOTE: For proper charge pump
operation, C1 must have a voltage rating greater than or
equal to V
IN
, while C2 and C
OUT
must have a voltage
rating greater than or equal to 2V
IN
.
Table 1 shows various values of C1/C2 and the corre-
sponding output resistance values for V
IN
=5V @ +25°C
Table 2 shows the output voltage ripple for various
values of C
OUT
(again assuming V
IN
= 5V @ +25
o
C). The
V
RIPPLE
values assume a 1mA output load current and a
0.1Ω ESR
COUT
.
Table 1. Output Resistance vs. C1/C2 (ESR = 0.1Ω).
C1,C2(
µ
F) TC1682 R
OUT
(
Ω
) TC1683 R
OUT
(
Ω
)
VIN
TC1684 R
OUT
(
Ω
)
120
102
84
+
C1
–VIN
0.33
1
3.3
633
262
120
184
120
95
SWITCH MATRIX
(1st STAGE)
ENABLE
OSCILLATOR
ENABLE
Table 2. Output Voltage Ripple vs. C
OUT2
(ESR = 0.1Ω), I
OUT
= 1mA
(1mA)
C
OUT
(
µ
F)
+
C2
VOUT = -2 VIN
TC1682 V
RIPPLE
(mV)
192
63
17
TC1683 V
RIPPLE
(mV)
60
21
8
TC1684 V
RIPPLE
(mV)
27
16
7
SWITCH MATRIX
(2nd STAGE)
+
ENABLE
COUT
0.33
1
3.3
SHDN
2001 Microchip Technology Inc.
Figure 1. Block Diagram
DS21537A
3
TC1682/3/4-1 8/14/00
Inverting Charge Pump Voltage
Doublers with Active High Shutdown
TC1682
TC1683
TC1684
Input Supply Bypassing
TheV
IN
input should be capacitively bypassed to reduce
AC impedance and minimize noise effects due to the
devices internal switching. It is recommended that a large
value capacitor (at least equal to C1) be connected from V
IN
to GND for optimal circuit performance.
Shutdown Input
The TC1682, TC1683 and TC1684 are enabled when
SHDN is low, and disabled when SHDN is high. This input
cannot be allowed to float. (If SHDN is not required, see the
TC2682/2683/2684 data sheet.) The SHDN input should be
limited to 0.3V above V
IN
.
Inverting Voltage Doubler
The most common application for the TC1682/1683/
1684 devices is the inverting voltage doubler (Figure 2).
This application uses three external capacitors: C1, C2, and
C
OUT
(NOTE: a power supply bypass capacitor is recom-
mended). The output is equal to –2V
IN
plus any voltage
drop due to loading. Refer to Tables 1 and 2 for capacitor
selection guidelines.
Layout Considerations
As with any switching power supply circuit, good layout
practice is recommended. Mount components as close
together as possible to minimize stray inductance and
capacitance. Also use a large ground plane to minimize
noise leakage into other circuitry.
V
IN
C
IN
7
C1
1
2
C2
3 C2–
C1–
C2+
TC1682
TC1683
TC1684
V
OUT
GND
5
4
C
OUT
V
OUT
R
L
C1+
6
V
IN
8
SHDN
TC1682 DEMO CARD
The TC1682 DEMO Card is a 2.0” x 2.0” card containing
both a TC1682 and a TC682 that allow the user to compare
the operation of each approach for generating a –2X func-
tion. Each circuit is fully assembled with the required
external capacitors along with variable load resistors that
allow the user to vary the output load current of each stage.
For convenience, several test points and jumpers are avail-
able for measuring various voltages and currents on the
demo board.
TC1682 DEMO CARD ASSEMBLY
Figure 3 is a schematic of the TC1682 DEMO Card, and
Figure 4 shows the assembly drawing and artwork for the
board. Table 3 lists the voltages that are monitored by the
test points and Table 4 lists the currents that can be
measured using the jumpers.
Table 3. TC1682 DEMO Card Test Points
Test Point
Voltage Measurement
TP1
V
IN
[ +1.8V to +5V]
TP2
Ground
TP3
Ground
TP4
TC682 (U1) Supply Voltage
TP5
TC682 (U1) Output Voltage [V
OUT1
]
TP6
TC1682 (U2) Supply Voltage
TP7
TC1682 (U2) Output Voltage [V
OUT2
]
TP8
TC1682 (U2) SHDN Input Voltage
TP9
DEMO Card Shutdown Input
Table 4. TC1682 DEMO Card Jumpers
Jumper
Current Measurement
J1
J2
J3
J4
J5
J6
TC682 (U1) Quiescent Current
TC1682 (U2) Quiescent Current
TC682 (U1) V
OUT1
Load Current
TC1682 (U2) V
OUT2
Load Current
TC1682 (U2) SHDN Input Current
Connect DEMO Card Shutdown Input to V
IN
Device
TC1682
TC1683
TC1684
C
IN
3.3µF
1µF
0.33µF
C1
3.3µF
1µF
0.33µF
C2
3.3µF
1µF
0.33µF
C
OUT
3.3µF
1µF
0.33µF
Figure 2. Inverting Voltage Doubler Test Circuit
TC1682/3/4-1 8/14/00
4
2001 Microchip Technology Inc.
DS21537A
Inverting Charge Pump Voltage
Doublers with Active High Shutdown
TC1682
TC1683
TC1684
Figure 3. TC1682 DEMO Card Schematic
Figure 4. TC1682 DEMO Card Assembly Drawing and Artwork
2001 Microchip Technology Inc.
DS21537A
5
TC1682/3/4-1 8/14/00
