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AAT3190 Schematic ( PDF Datasheet ) - ANALOGICTECH

Teilenummer AAT3190
Beschreibung Positive/Negative Charge Pump for Voltage Bias
Hersteller ANALOGICTECH
Logo ANALOGICTECH Logo 




Gesamt 16 Seiten
AAT3190 Datasheet, Funktion
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
1






AAT3190 Datasheet, Funktion
AAT3190
Positive/Negative Charge Pump for Voltage Bias
Typical Characteristics
Positive Output Efficiency vs. Load Current
(VIN = 5.0V)
80
VPOS = 12.3V
70
60
85°C
25°C
50
40
30
20
0
10 20
IPOS (mA)
30
40
Negative Output Efficiency vs. Load Current
(VIN = 5.0V)
80
85°C
70
25°C
60
50
40
30
VNEG = -7.3V
20
0 10
20
INEG (mA)
30
40
VPOS Load Transient
250
200
150
100
50
0
-50
-100
-150
50µs/div
20
10
0
-10
-20
-30
-40
-50
-60
VNEG Load Transient
250
200
150
100
50
0
-50
-100
-150
50µs/div
20
10
0
-10
-20
-30
-40
-50
-60
AAT 3190 Power-Up Sequence
20
Enable
16
12
8 VPOS
4
0
VNEG
-4
-8
-12
500µsec/div
4
2
0
-2
-4
-6
-8
-10
-12
AAT3190-1 Power-Up Sequence
20
Enable
16
12
8
VPOS
4
0
-4 VNEG
-8
-12
500µsec/div
4
2
0
-2
-4
-6
-8
-10
-12
6 3190.2005.03.1.0

6 Page









AAT3190 pdf, datenblatt
AAT3190
Positive/Negative Charge Pump for Voltage Bias
The voltage rating for the nth flying capacitor in the
negative stage (see Table 2) is:
VFLY(n) = VFWD - VBULK(n)
VIN = 5.0V, VFWD = 0.3V
Stages (n)
VBULK(n)
1 -4.4V
2 -8.8V
3 -13.2V
4 -17.6V
5 -22.0V
6 -26.4V
VFLY(n)
4.7V
9.1V
13.5V
17.9V
22.3V
26.7V
Table 2: Negative Output Capacitor Voltages.
Single Output Operation
If only one of the two channels is needed, it is pos-
sible to disable either output. Connect the respec-
tive FB pin to VIN to disable the output (e.g., con-
nect FBN to VIN in order to disable the negative
output).
Input Capacitors
Input Capacitor
The primary function of the input capacitor is to pro-
vide a low impedance loop for the edges of pulsed
current drawn by the IC. A low ESL X7R or X5R type
ceramic capacitor is ideal for this function. The size
required will vary depending on the load, output volt-
age, and input voltage characteristics. Typically, the
input capacitor should be 5 to 10 times the flying
capacitor. If the source impedance of the input sup-
ply is high, a larger capacitor may be required. To
minimize stray inductance, the capacitor should be
placed as closely as possible to the IC. This keeps
the high frequency content of the input current local-
ized, minimizing radiated and conducted EMI.
Rectifier Diodes
For the rectifiers, use Schottky diodes with a volt-
age rating of 1.5 times the input voltage. The max-
imum steady-state voltage seen by the rectifier
diodes for both the positive and negative charge
pumps (regardless of the number of stages) is:
VREVERSE = VIN - VF
The BAT54S dual Schottky is offered in a SOT23
package that provides a convenient pin-out for the
voltage doubler configuration. The BAT54SDW
quad Schottky in a SOT363 (2x2mm) package is a
good choice for multiple-stage charge pump config-
uration (see Figure 3, Evaluation Board Schematic).
PC Board Layout
The input and reference capacitor should be placed
as close to the IC as possible. Place the program-
ming resistors (R1-R4) close to the IC, minimizing
trace length to FBN and FBP. Figures 4 and 5 display
the evaluation board layout with the TSOPJW-12
package.
12 3190.2005.03.1.0

12 Page





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