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PDF AAT3190 Data sheet ( Hoja de datos )
| Número de pieza | AAT3190 | |
| Descripción | Positive/Negative Charge Pump for Voltage Bias | |
| Fabricantes | ANALOGICTECH | |
| Logotipo |  |
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AAT3190
Positive/Negative Charge Pump for Voltage Bias
General Description
The AAT3190 charge pump controller provides the
regulated positive and negative voltage biases
required by active matrix thin-film transistor (TFT)
liquid-crystal displays (LCDs), charge-coupled
device (CCD) sensors, and organic light emitting
diodes (OLEDs). Two low-power charge pumps
convert input supply voltages ranging from 2.7V to
5.5V into two independent output voltages.
The dual low-power charge pumps independently
regulate a positive (VPOS) and negative (VNEG) out-
put voltage. These outputs use external diode and
capacitor multiplier stages (as many stages as
required) to regulate output voltages up to ±25V.
Built-in soft-start circuitry prevents excessive in-
rush current during start-up. A high switching fre-
quency enables the use of small external capaci-
tors. The device’s shutdown feature disconnects
the load from VIN and reduces quiescent current to
less than 1.0µA.
The AAT3190 is available in an MSOP-8 or
TSOPJW-12 package and is specified over the
-40°C to +85°C operating temperature range.
Features
ChargePump™
• VIN Range: 2.7V to 5.5V
• Adjustable ± Dual Charge Pump
• Positive Supply Output Up to +25V
• Negative Supply Output Down to -25V
• Up to 30mA Output Current
• 1.0MHz Switching Frequency
• <1.0µA Shutdown Current
• Internal Power MOSFETs
• Internally Controlled Soft Start
• Fast Transient Response
• Ultra-Thin Solution (No Inductors)
• -40°C to +85°C Temperature Range
• Available in 8-Pin MSOP or 12-Pin TSOPJW
Package
Applications
• CCD Sensor Voltage Bias
• OLEDs
• Passive-Matrix Displays
• Personal Digital Assistants (PDAs)
• TFT Active-Matrix LCDs
Typical Application
INPUT
EN
NEGATIVE
OUTPUT
IN
EN
DRVN
AAT3190
FBN
DRVP
REF
FBP
GND
POSTIVE
OUTPUT
3190.2005.03.1.0
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1 page  
AAT3190
Positive/Negative Charge Pump for Voltage Bias
Typical Characteristics
Quiescent Current vs. Temperature
350
VFBP = 1.5V
330 VFBN = -0.2V
310
290
270
250
-40
-15 10
35
Temperature (°C)
60
85
Switching Frequency vs. Temperature
1000
950
900
850
800
-40
-15 10
35
Temperature (°C)
60
85
Reference Voltage vs. Temperature
1.22
1.21
1.2
1.19
1.18
-40
-15 10
35
Temperature (°C)
60
85
Maximum VOUT vs. VIN
(IOUT = 5mA and 15mA)
15
12.5
10
IOP = 5mA
7.5
5
2.5
IOP = 15mA
0
-2.5
-5
ION = 15mA
-7.5
-10
-12.5
ION = 5mA
-15
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
Positive Output Voltage vs. Load Current
(TA = 25°C)
12.4
VIN = 5.0V
12.2
12
11.8
11.6
11.4
0
5 10 15 20 25 30 35 40
IPOS (mA)
Negative Output Voltage vs. Load Current
(TA = 25°C)
-6.5
-6.75
VIN = 5.0V
-7
-7.25
-7.5
-7.75
-8
0
10 20
INEG (mA)
30
40
3190.2005.03.1.0
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5 Page 
AAT3190
Positive/Negative Charge Pump for Voltage Bias
With R2 selected, R1 can be determined:
R1 =
VNEG · R2
-VREF
VOP
The positive output voltage is set by way of a resis-
tive divider from the output (VOP) to the FBP and
ground pin. Limiting the size of R4 reduces the
effect of the FBP bias current. For less than 0.1%
error, limit R4 to less than 12kΩ.
IPGM
=
VREF
R4
=
1.2V
12kΩ
=
100µA
IFBP
IPGM
=
0.1µA
100µA =
0.1%
Once R4 has been determined, solve for R3:
R3
=
R4
·
⎛
⎝
VO
VREF
-
1⎞⎠
Flying and Output Capacitor
The flying capacitor minimum value is limited by
the output power requirement, while the maximum
value is set by the bandwidth of the power supply.
If CFLY is too small, the output may not be able to
deliver the power demanded, while too large of a
capacitor may limit the bandwidth and time
required to recover from load and line transients. A
0.1µF X7R or X5R ceramic capacitor is typically
used. The voltage rating of the flying and reservoir
output capacitors varies with the number of charge
pump stages. The reservoir output capacitor
should be roughly 10 times the flying capacitor.
Use larger capacitors for reduced output ripple. A
1µF X7R or X5R type ceramic is typically used.
Positive Output Capacitor Voltage
Ratings
The absolute steady-state maximum output voltage
(neglecting the internal RDS(ON) drop of the internal
MOSFETs) for the nth stage is:
VBULK(n) = (n + 1) · VIN - 2 · n · VFWD
where VFWD is the estimated forward drop of the
Schottky diode. This is also the voltage rating
required for the nth bulk capacitor in the positive
output charge pump.
The voltage rating for the nth flying capacitor in the
positive stage is:
VFLY(n) = VBULK(n + 1) - VFWD
where VBULK(0) is the input voltage. (See Table 1.)
VIN = 5.0V, VFWD = 0.3V
Stages (n)
VBULK(n)
1 9.4V
2 13.8V
3 18.2V
4 22.6V
5 27.0V
6 31.4V
VFLY(n)
4.7V
9.1V
13.5V
17.9V
22.3V
26.7V
Table 1: Positive Output Capacitor Voltages.
Negative Output Capacitor Voltage
Ratings
The absolute steady-state maximum output voltage
(neglecting the internal RDS(ON) drop of the internal
MOSFETs) for the nth stage is:
VBULK(n) = -n · VIN + 2 · n · VFWD
This is also the voltage rating required for the nth
bulk capacitor in the negative output charge pump.
3190.2005.03.1.0
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet AAT3190.PDF ] | |
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