ADM8832 Analog Devices, ADM8832 Datasheet

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ADM8832

Manufacturer Part Number
ADM8832
Description
Charge Pump Regulator for Color TFT Panel
Manufacturer
Analog Devices
Datasheet

Specifications of ADM8832

Peak Efficiency (%)
90%
Switching Freq
100kHz
Vin Max (v)
3.6V
Vin Min (v)
2.6V
Package
20-Lead LFCSP
Out Voltage (v)
5V; -10.2V; 15.3V
Ripple Out (p-p)
10mV p-p; 50mV p-p; 50mV p-p

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FEATURES
3 output voltages (+5.1 V, +15.3 V, −10.2 V) from one 3 V
Power efficiency optimized for use with TFT in mobile
Low quiescent current
Low shutdown current (<1 µA)
Fast transient response
Shutdown function
Power saving during blanking period
Option to use external ldo
APPLICATIONS
Handheld instruments
TFT LCD panels
Cellular phones
GENERAL DESCRIPTION
The ADM8832 is a charge pump regulator used for color thin
film transistor (TFT) liquid crystal displays (LCD). Using charge
pump technology, the device can be used to generate three
output voltages (+5.1 V ±2%, +15.3 V, −10.2 V) from a single
3 V input supply. These outputs are then used to provide
supplies for the LCD controller (+5.1 V) and the gate drives for
the transistors in the panel (+15.3 V and −10.2 V). Only a few
external capacitors are needed for the charge pumps. An
efficient low dropout voltage regulator also ensures that the
power efficiency is high and provides a low ripple 5.1 V output.
This LDO can be shut down and an external LDO used to
regulate the 5 V doubler output and drive the input to the
charge pump section, which generates the +15.3 V and −10.2 V
outputs if so required by the user.
The ADM8832 has an internal 100 kHz oscillator for use in
scanning mode, but the part must be clocked by an external
clock source in blanking (low current) mode. The internal
oscillator is used to clock the charge pumps during scanning
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
input supply
phones
mode where the current is highest. During blanking periods, the
ADM8832 switches to an external, lower frequency clock. This
allows the user to vary the frequency and maximize power
efficiency during blanking periods. The tolerances on the output
voltages are seamlessly maintained when switching from scan-
ning mode to blanking mode or vice versa.
The ADM8832 power saving features include low power
shutdown and reduced quiescent current consumption during
the blanking periods. The 5.1 V output consumes the most
power, so power efficiency is also maximized on this output
with an oscillator enabling scheme (Green Idle™). This
effectively senses the load current that is flowing and turns on
the charge pump only when charge needs to be delivered to the
5 V pump doubler output.
The ADM8832 is fabricated using CMOS technology for minimal
power consumption. The part is packaged in a 20-lead LFCSP
(lead frame chip scale package).
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703
LDO_ON/
BLANK
SCAN/
CLKIN
SHDN
OFF
ADM8832
SHUTDOWN
OSCILLATOR
CONTROL
GENERATOR
CONTROL
LOGIC
FUNCTIONAL BLOCK DIAGRAM
TIMING
Charge Pump Regulator
VOLTAGE
V
TRIPLER
CC
© 2004 Analog Devices, Inc. All rights reserved.
DISCHARGE
GND
for Color TFT Panel
C5
2.2µF
Figure 1.
REGULATOR
DOUBLER
DOUBLE
VOLTAGE
VOLTAGE
INVERTER
VOLTAGE
TRIPLE
LDO
C1+
C1–
VOUT
LDO IN
+5VOUT
+5VIN
C2+
C2–
C3+
C3–
+15VOUT
C4+
C4–
–10VOUT
ADM8832
www.analog.com
C2
1µF
C4
1µF
C3
1µF
C8
1µF
C9
1µF
C1
2.2µF
C6
2.2µF
C7
2.2µF
+5.1V
+15.3V
–10.2V

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ADM8832 Summary of contents

Page 1

... Handheld instruments TFT LCD panels Cellular phones GENERAL DESCRIPTION The ADM8832 is a charge pump regulator used for color thin film transistor (TFT) liquid crystal displays (LCD). Using charge pump technology, the device can be used to generate three output voltages (+5.1 V ±2%, +15.3 V, −10.2 V) from a single 3 V input supply ...

Page 2

... ADM8832 TABLE OF CONTENTS Specifications..................................................................................... 3 Timing Specifications .................................................................. 4 Absolute Maximum Ratings............................................................ 5 Thermal Characteristics .............................................................. 5 ESD Caution.................................................................................. 5 Pin Configuration and Function Descriptions............................. 6 Typical Performance Characteristics ............................................. 7 REVISION HISTORY 4/04—Changed from Rev Rev. A Changes to Outline Dimensions................................................... 11 Updated Ordering Guide............................................................... 11 7/03—Revision 0: Initial Version Theory of Operation ...................................................................... 10 Scanning and Blanking.............................................................. 10 Power Sequencing ...

Page 3

... Scanning Period Blanking Period I = –100 µA L Relative to 5.1 V Output 100 µA (Scanning) L Relative to 5.1 V Output µA (Blanking) L Scanning Period SHDN Low = Shutdown Mode SHDN High = Normal Mode Low = BLANK Period High = SCAN Period Low = External LDO High = Internal LDO ADM8832 ...

Page 4

... ADM8832 Parameter CLKIN Minimum Frequency Input Voltage Digital Input Current 1 Digital Input Capacitance 1 Guaranteed by design. Not 100% production tested. Specifications are subject to change without notice. TIMING SPECIFICATIONS –40°C to +85°C, unless otherwise noted; C1, C5, C6 2.2 µF, C2, C3, C4, C8 µF, CLKIN = 1 kHz in ...

Page 5

... V to +0.3 V other conditions above those listed in the operational sections −0 + this specification is not implied. Exposure to absolute −40°C to +85°C maximum rating conditions for extended periods may affect 3.55 W device reliability. −65°C to +150°C Class I Rev Page ADM8832 ...

Page 6

... Drive Mode Input CMOS logic. A logic high places the part in scan (high current) mode, and the charge pump is driven by the internal oscillator. A logic low places the part in blanking (low current) mode, and the charge pump is driven by the (slower) external oscillator. This is a power saving feature on the ADM8832. 9 CLKIN External CLOCK Input ...

Page 7

... Figure 6. LDO Efficiency in Scanning Mode with OUTPUT CURRENT ( µ A) Figure 7. +15 V/−10 V Efficiency vs. Output Current in Blanking Mode OUTPUT CURRENT ( µ A) Figure 8. +15 V/−10 V Efficiency vs. Output Current in Scanning Mode ADM8832 100 ...

Page 8

... ADM8832 5.30 5.25 5.20 DEVICE 1 @ +85°C 5.15 DEVICE 1 @ +25°C 5.10 5.05 5.00 4.95 4.90 2.6 2.7 2.8 2.9 3.0 3.1 3.2 V (V) CC Figure 9. LDO Variation over Supply and Temperature 300 250 200 ICC (SCAN) 150 100 ICC (BLANK 2.6 2.7 2.8 2.9 3.0 3.1 3.2 V (V) CC Figure 10. Supply Current vs. Voltage TEK STOP: 2.50MS/s 23 ACQS [ T V OUT OUTPUT RIPPLE RIPPLE ...

Page 9

... T 1 –10V OUTPUT T T 5VOUT 2 CH1 5.00V CH2 5.00V M10.0ms CH1 CH3 5.00V Figure 15. +15 V and −10 V Outputs at Power-Down (Unloaded) 20.1 20.0 19.9 19.8 19.7 19.6 19.5 19.4 –40 –20 0V Figure 16. Power Dissipation over Temperature, V Rev Page ADM8832 TEMPERATURE (°C) = 3.6 V, Scanning Mode CC with All O/Ps at Maximum Load ...

Page 10

... V supply for the TFT panel to power on correctly. The ADM8832 controls this sequence. When the device is turned on (a logic high on SHDN ), the ADM8832 allows the −10 V output to ramp immediately, but holds off the +15 V output. It continues to do this until the negative output reaches − ...

Page 11

... Temperature Range ADM8832ACP −40°C to +85°C ADM8832ACP-REEL −40°C to +85°C ADM8832ACP-REEL7 −40°C to +85°C 1 ADM8832ACPZ −40°C to +85°C 1 ADM8832ACPZ-REEL −40°C to +85°C 1 ADM8832ACPZ-REEL7 −40°C to +85° Pb-free part. 0.60 4.00 MAX BSC SQ 0.60 MAX TOP 3.75 VIEW BCS SQ ...

Page 12

... ADM8832 NOTES © 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03759–0–5/04(A) Rev Page ...

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