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MAX17122 Schematic ( PDF Datasheet ) - Maxim Integrated Products

Teilenummer MAX17122
Beschreibung Boost-Buck Regulator
Hersteller Maxim Integrated Products
Logo Maxim Integrated Products Logo 




Gesamt 30 Seiten
MAX17122 Datasheet, Funktion
19-4951; Rev 1; 11/09
EVAALVUAAILTAIOBNLEKIT
Step-Up, Step-Down Regulator, Gate-On Charge Pump,
and Boost-Buck Regulator for TV TFT LCD Display
General Description
The MAX17122 multiple-output power-supply IC gener-
ates all the supply rails for thin-film transistor (TFT) liquid-
crystal display (LCD) TV panels. It can operate from 8V
to 16.5V input voltages and is optimized for LCD TV
panel applications running directly from 12V regulated
supplies. It includes a 22V internal-switch step-down
regulator for digital logic, a 22V internal switch step-
up regulator to power the TFT source drivers, and a
temperature-compensated 36V internal-switch boost-
buck regulator that produces a negative output that can
vary according to the temperature sensed by an exter-
nal NTC thermistor. All three of these regulators feature
high-efficiency and fixed-frequency operation. High-
frequency operation allows the use of small inductors
and capacitors, resulting in a compact solution.
The MAX17122 includes a positive charge-pump linear
regulator controller that uses an external pnp bipolar
junction transistor (BJT) to typically form a regulated
charge-pump doubler to supply the LCD positive gate-
driver supply voltage. A negative gate-driver supply is
derived linearly between the boost-buck regulator’s out-
put and ground, using an external npn BJT connected to
ground and a small bypass capacitor.
Other features include an external-capacitor-timed,
open-drain, power-good output that monitors the step-
down regulator’s feedback and a simple untimed output
that monitors the positive charge-pump linear regulator’s
feedback. A high-voltage stress function is available for
the step-up regulator output. The GATE output directly
drives an external p-channel MOSFET to provide True
ShutdownK of the step-up output.
The MAX17122 is available in a 6mm x 6mm, 40-pin thin
QFN lead-free package and operates over the -40NC to
+85NC temperature range.
LCD TV Panels
Applications
Features
S 8V to 16.5V Operating Range
S 750kHz Switching Frequency
S 22V Internal-Switch High-Performance Step-Up
Regulator
Fast Load-Transient Response
Current-Mode PWM Operation
100mI, 3.9A nMOS Switch
Capacitor-Adjustable Soft-Start
High-Voltage Stress Function
Drives External pMOS Shutdown Switch
S 22V Internal-Switch Step-Down Regulator
Preset 1% Accurate 3.3V Output Voltage or
Adjustable Output (Dual Mode™)
Current-Mode PWM Operation
200mI, 2.5A nMOS Switch
Capacitor-Adjustable Power-Good Output
S 36V Internal-Switch Boost-Buck Regulator
Temperature-Compensated Output
Programmable Fixed Levels with Temperature-
Controlled Transition
Current-Mode PWM Operation
200mI, 1.8A pMOS Switch
S Positive Charge-Pump Linear Regulator Controller
Adjustable 1% Accurate Output Voltage
Uses External pnp Transistor
Regulates Switching-Node-Driven Charge-
Pump Doubler
Power-Good Output
S Negative Linear Regulator Controller
Adjustable 1.5% Accurate Output Voltage
Uses External npn Transistor
S Soft-Start for All Outputs
S Adjustable Power-Up Sequence
S Timed-Output Fault Protection with Restart for All
Outputs
S Latched Thermal-Shutdown Protection
S 40-Pin, 6mm x 6mm Thin QFN Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX17122ETL+ -40NC to +85NC
40 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
True Shutdown and Dual Mode are trademarks of Maxim
Integrated Products, Inc.
Pin Configuration appears at end of data sheet.
_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
http://www.Datasheet4U.com






MAX17122 Datasheet, Funktion
Step-Up, Step-Down Regulator, Gate-On Charge Pump,
and Boost-Buck Regulator for TV TFT LCD Display
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, VIN = VIN2 = VIN3 = 12V, TA = -40°C to +85°C.) (Note 2)
PARAMETER
GENERAL
IN, IN2, IN3
Input-Voltage Range
CONDITIONS
MIN TYP MAX UNITS
8
16.5
V
IN + IN2 + IN3
Quiescent Current
IN + IN2 + IN3
Quiescent Current
IN + IN2 + IN3
Shutdown Current
SMPS Operating Frequency
IN Undervoltage-Lockout
Threshold
Only LX2 and LX3 switching (VFB1 = VFBP = 1.5V, VFB2 =
1.1V, VFB3 = 1.8V, VFBN = 1.5V); VEN1 = VEN2 = 5V
LX2 and LX3 not switching (VFB1 = VFB2 = VFBP = 1.5V,
VFBN = 1.5V, VFB3 = 0); VEN1 = VEN2 = 5V
EN1 = EN2 = AGND (shutdown)
638
VIN rising, 2.5% hysteresis
6
15 mA
4 mA
1 mA
862 kHz
8V
VL REGULATOR
VL Output Voltage
VL Undervoltage-Lockout
Threshold
IVL = 10mA, VFB1 = VFB2 = VFBP = 1.1V, VFBN = 0.75V,
VFB3 = 1.8V (all regulators switching)
VL rising, 2.5% hysteresis
4.9
3.6
5.1 V
4.4 V
STEP-DOWN REGULATOR
OUTB Voltage in Fixed Mode
FB2 Voltage in Adjustable Mode
FB2 Adjustable-Mode
Threshold Voltage
FB2 = AGND, no load (Note 1)
VOUTB = 3.3V, no load (Note 1)
Dual-mode comparator
-40NC < TA < +85NC
-40NC < TA < +85NC
3.25
1.23
0.10
3.35
1.27
0.20
V
V
V
Output Voltage Adjust Range
FB2 Fault-Trip Level
FB2 Input-Bias Current
LX2-to-IN2 nMOS Switch
On-Resistance
Step-down output
Falling edge
VFB2 = 1.5V
1.5
0.96
50
3.6
1.04
200
400
V
V
nA
mI
LX2-to-GND1 nMOS Switch
On-Resistance
6 24 I
BST2-to-VL pMOS Switch
On-Resistance
6 24 I
LX2 Positive Current Limit
Maximum Duty Factor
BUCK-BOOST REGULATOR
FB3 Regulation Voltage
FB3 Input-Bias Current
FB3 Pulldown Resistance
FB3 Fault-Trip Level
LX3-to-IN3 pMOS Switch
On-Resistance
No load, VNTC = 2V
VFB3 = 0.5V
EN1 = AGND
Rising edge
-40NC < TA < +85NC
2.5
68
1.62
-50
300
1.9
3.5
82
1.68
-210
1200
2.1
400
A
%
V
nA
I
V
mI
6 ______________________________________________________________________________________

6 Page









MAX17122 pdf, datenblatt
Step-Up, Step-Down Regulator, Gate-On Charge Pump,
and Boost-Buck Regulator for TV TFT LCD Display
(TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0
NEGATIVE LINEAR REGULATOR
NORMALIZED LOAD REGULATION
100 200 300 400
LOAD CURRENT (mA)
500
POWER-UP SEQUENCE OF
ALL SUPPLY OUTPUTS
MAX17122 toc19
VIN
VEN1
0V VOUTB
0V VEN2
0V VGON
VAVDD
0V
0V, 0V
0V
0V
VIN = 10V/div
VEN1 = 5V/div
VOUTB = 5V/div
VEN2 = 5V/div
10ms/div
VGOFF1
VGOFF2
VGON = 10V/div
VAVDD = 10V/div
VGOFF1 = 5V/div
VGOFF2 = 10V/div
NEGATIVE LINEAR REGULATOR
LOAD-TRANSIENT
RESPONSE (0A TO 100mA)
MAX17122 toc18
VGOFF1
0V (AC-COUPLED)
100mV/div
ILOAD
0A 50mA/div
20µs/div
RESET FUNCTION
MAX17122 toc20
VOUTB
2V/div
0V VDEL
1V/div
0V
VRESET
0V 2V/div
4ms/div
12

12 Page





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