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PDF TC1236 Data sheet ( Hoja de datos )
| Número de pieza | TC1236 | |
| Descripción | (TC1235 / TC1236 / TC1237) Inverting Dual Charge Pump Voltage Converters with Shutdown | |
| Fabricantes | Microchip Technology | |
| Logotipo |  |
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TC1235
TC1236
TC1237
Inverting Dual (–VIN, –2VIN) Charge Pump Voltage Converters with Shutdown
FEATURES
s 10-Pin MSOP Package
s Operates from 1.8V to 5.5V
s Up to 5mA Output Current at –VIN Pin
s Up to 1mA Output Current at –2VIN Pin
s Power-Saving Shutdown Mode
s –VIN and –2VIN Outputs Available
s Low Active Supply Current
.......................................... 120µA (MAX) for TC1235
.......................................... 360µA (MAX) for TC1236
.......................................... 1.5mA (MAX) for TC1237
s Fully Compatible with 1.8V Logic Systems
TYPICAL APPLICATIONS
s LCD Panel Bias
s Cellular Phones PA Bias
s Pagers
s PDAs, Portable Dataloggers
s Battery Powered Devices
GENERAL DESCRIPTION
The TC1235/1236/1237 are CMOS dual inverting
charge pump voltage converters with a low power shutdown
mode in MSOP 10-Pin packages. Only four external capaci-
tors are required for full circuit implementation. Switching
frequencies are 12kHz for the TC1235, 35kHz for the
TC1236 and 125kHz for the TC1237. When the shutdown
pin is held at a logic low, the device goes into a very low
power mode of operation, consuming less than 1µA of
supply current.
These devices provide both a negative voltage inver-
sion (available at the –VIN output), and a negative doubling
voltage inversion (available at the –2 VIN output) with a low
output impedance capable of providing output currents up to
5mA for the –VIN output and 1mA for the –2VIN output. The
input voltage can range from +1.8V to +5.5V.
ORDERING INFORMATION
Part No. Package Osc Freq (KHz) Temp Range
TC1235EUN 10-Pin MSOP
TC1236EUN 10-Pin MSOP
TC1237EUN 10-Pin MSOP
12
35
125
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
PIN CONFIGURATION
10-Pin MSOP
C1– 1
C2+ 2
NC 3
C2– 4
TC1235
TC1236
TC1237
10 –VIN
9 C1+
8 SHDN
7 VIN
–2 VIN 5
6 GND
Notes:
1) C1 and COUT1 must have a voltage rating greater
than or equal to VIN
2) C2 and COUT2 must have a voltage rating greater
than or equal to 2VIN
© 2001 Microchip Technology Inc. DS21371A
TYPICAL OPERATING CIRCUIT
+ C1+
C1
INPUT
VIN
OUTPUT 1
C1– –VIN
C2+ + COUT1
+
C2
TC1235
C2–
TC1236
TC1237
SHDN
ON
OFF
GND
NC
–2 VIN
OUTPUT 2
+ COUT2
TC1235/6/7-1 3/24/00
1 page  
Inverting Dual (–VIN, –2VIN)
Charge Pump Voltage Converters
with Shutdown
TC1235
TC1236
TC1237
Input Supply Bypassing
Layout Considerations
TheVIN input should be capacitively bypassed to reduce
AC impedance and minimize noise effects due to the switch-
ing internal to the device. It is recommended that a large
value capacitor (at least equal to C1) be connected from VIN
to GND for optimal circuit performance.
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.
Shutdown Input
TC1235 DEMO Card
The TC12351/1236/1237 is enabled when /SHDN is
high, and disabled when /SHDN is low. This input cannot be
allowed to float. (If /SHDN is not required, see the TC1225/
1226/1227 data sheet.) The /SHDN input should be limited
to 0.3V above VIN to avoid significant current flows.
Dual Voltage Inverter
The most common application for the TC1235/1236/
1237 devices is the dual voltage inverter (Figure 2). This
application uses four external capacitors: C1, C2, COUT1,
and COUT2 (NOTE: a power supply bypass capacitor is
recommended). The outputs are equal to – VIN and –2VIN
plus any voltage drops due to loading. Refer to Tables 1a,
1b, 2a, and 2b for capacitor selection guidelines.
Device
TC1235
TC1236
TC1237
CIN C1
3.3µF 3.3µF
1µF 1µF
0.33µF 0.33µF
C2
1µF
0.33µF
0.1µF
COUT1
3.3µF
1µF
0.33µF
COUT2
1µF
0.33µF
0.1µF
VIN
CIN
C1
C2
9 C1+
1 C1–
2 C2+
4 C2–
78
VIN SHDN
–VIN 10
COUT1
TC1235
TC1236
TC1237
5
–2VIN
COUT2
GND
6
RL1
RL2
VOUT1
VOUT2
Figure 2. Dual Voltage Inverter Test Circuit
The TC1235 DEMO Card is a 2.0” x 2.0” card containing
both a TC1235 and two cascaded TC1219s that allow the
user to compare the operation of each approach for gener-
ating a –1X and –2X function. 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 available for measuring various voltages
and currents on the demo board.
Figure 3 is a schematic of the TC1235 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. TC1235 DEMO Card Test Points
TEST POINT VOLTAGE MEASUREMENT
TP1
TP2
TP3
TP4
TP5
TP6
TP7
TP8
TP9
TP10
VIN [+5V]
GROUND
GROUND
TC1219 U1 OUTPUT [-5V(1)]
TC1219 U2 OUTPUT [-10V(1)]
TC1235 STAGE 1 OUTPUT [-5V(2)]
TC1235 STAGE 2 OUTPUT [-10V(2)]
EXTERNAL /SHDN INPUT
TC1219 U1 /SHDN INPUT
TC1235 U3 /SHDN INPUT
Table 4. TC1235 DEMO Card Jumpers
JUMPER
CURRENT MEASUREMNT
J1 DUAL TC1219 QUIESCENT CURRENT
J2 TC1235 QUIESCENT CURRENT
J3 TC1219 U1 [-5V(1)] LOAD CURRENT
J4 TC1219 U2 [-10V(1)] LOAD CURRENT
J5 TC1235 STAGE 1 [-5V(2)] LOAD CURRENT
J6 TC1235 STAGE 2 [-10V(2)] LOAD CURRENT
J7 TC1219 U1 /SHDN INPUT CURRENT
J8 TC1235 U3 /SHDN INPUT CURRENT
J9 GROUND EXTERNAL /SHDN INPUT
© 2001 Microchip Technology Inc. DS21371A
5
TC1235/6/7-1 3/24/00
5 Page | ||
| Páginas | Total 10 Páginas | |
| PDF Descargar | [ Datasheet TC1236.PDF ] | |
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