19-1795; Rev 1; 9/05
Low-Power Triple-Output TFT LCD DC-DC
Converter
General Description
The MAX1779 triple-output DC-DC converter provides
highly efficient regulated voltages required by small
active matrix, thin-film transistor (TFT) liquid-crystal dis-
plays (LCDs). One high-power DC-DC converter and
two low-power charge pumps convert the +2.7V to
+5.5V input supply voltage into three independent out-
put voltages.
The primary high-power DC-DC converter generates a
boosted output voltage (V
MAIN
) up to 13V that is regu-
lated within ±1%. The low-power BiCMOS control cir-
cuitry and the low on-resistance (1Ω) of the integrated
power MOSFET allows efficiency up to 91%. The
250kHz current-mode pulse-width modulation (PWM)
architecture provides fast transient response and
allows the use of ultra-small inductors and ceramic
capacitors.
The dual charge pumps independently regulate one
positive output (V
POS
) and one negative output (V
NEG
).
These low-power outputs use external diode and
capacitor stages (as many stages as required) to regu-
late output voltages up to +40V and down to -40V. A
proprietary regulation algorithm minimizes output rip-
ple, as well as capacitor sizes for both charge pumps.
The MAX1779 is available in the ultra-thin TSSOP pack-
age (1.1mm max height).
Features
♦
Three Integrated DC-DC Converters
♦
250kHz Current-Mode PWM Boost Regulator
Up to +13V Main High-Power Output
±1% Accuracy
High Efficiency (91%)
♦
Dual Charge-Pump Outputs
Up to +40V Positive Charge-Pump Output
Down to -40V Negative Charge-Pump Output
♦
Internal Supply Sequencing
♦
Internal Power MOSFETs
♦
+2.7V to +5.5V Input Supply
♦
0.1µA Shutdown Current
♦
0.5mA Quiescent Current
♦
Internal Soft-Start
♦
Power-Ready Output
♦
Ultra-Small External Components
♦
Thin TSSOP Package (1.1mm max)
MAX1779
Ordering Information
PART
MAX1779EUE
MAX1779EUE+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 TSSOP
16 TSSOP
+
Denotes lead-free package.
Pin Configuration
________________________Applications
TFT Active-Matrix LCD Displays
Passive-Matrix LCD Displays
PDAs
Digital-Still Cameras
Camcorders
TOP VIEW
RDY 1
FB 2
INTG 3
IN 4
GND 5
REF 6
FBP 7
FBN 8
16 TGND
15 LX
14 PGND
MAX1748
MAX8726
13 SUPP
12 DRVP
11 SUPN
10 DRVN
9
SHDN
TSSOP
Typical Operating Circuit appears at end of data sheet.
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Low-Power Triple-Output TFT LCD DC-DC
Converter
MAX1779
ABSOLUTE MAXIMUM RATINGS
IN,
SHDN,
TGND to GND .........................................-0.3V to +6V
DRVN to GND .........................................-0.3V to (V
SUPN
+ 0.3V)
DRVP to GND..........................................-0.3V to (V
SUPP
+ 0.3V)
PGND to GND.....................................................................±0.3V
RDY
to GND ...........................................................-0.3V to +14V
LX, SUPP, SUPN to PGND .....................................-0.3V to +14V
INTG, REF, FB, FBN, FBP to GND ...............-0.3V to (V
IN
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
16-Pin TSSOP (derate 9.4mW/°C above +70°C) ..........755mW
Operating Temperature Range
MAX1779EUE ..................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
IN
= +3.0V,
SHDN
= IN, V
SUPP
= V
SUPN
= +10V, TGND = PGND = GND, C
REF
= 0.22µF, C
INTG
= 2200pF,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Input Supply Range
Input Undervoltage Threshold
IN Quiescent Supply Current
SUPP Quiescent Current
SUPN Quiescent Current
IN Shutdown Current
SUPP Shutdown Current
SUPN Shutdown Current
MAIN BOOST CONVERTER
Output Voltage Range
FB Regulation Voltage
FB Input Bias Current
Operating Frequency
Oscillator Maximum Duty Cycle
Load Regulation
Line Regulation
Integrator Gm
LX Switch On-Resistance
LX Leakage Current
LX Current Limit
Maximum RMS LX Current
FB Fault Trip Level
POSITIVE CHARGE PUMP
V
SUPP
Input Supply Range
V
SUPP
Falling edge
1.07
2.7
R
LX(ON)
I
LX
I
LIM
I
LX
= 100mA
V
LX
= +13V
350
I
MAIN
= 0 to 50mA, V
MAIN
= +5V
V
MAIN
V
FB
I
FB
f
OSC
V
FB
= +1.25V, INTG = GND
V
IN
1.235
-50
212
79
250
85
0.1
0.1
320
1.0
0.01
450
250
1.1
1.14
13
2.0
20
650
1.248
13
1.261
50
288
92
V
V
nA
kHz
%
%
%/V
μs
Ω
μA
mA
mA
V
V
SYMBOL
V
IN
V
UVLO
I
IN
I
SUPP
I
SUPN
V
IN
rising, 40mV hysteresis (typ)
V
FB
= V
FBP
= +1.5V, V
FBN
= -0.2V
V
FBP
= +1.5V
V
FBN
= -0.1V
V
SHDN
= 0, V
IN
= +5V
V
SHDN
= 0, V
SUPP
= +13V
V
SHDN
= 0, V
SUPN
= +13V
CONDITIONS
MIN
2.7
2.2
2.4
0.5
0.25
0.25
0.1
0.1
0.1
TYP
MAX
5.5
2.6
1
0.55
0.55
10
10
10
UNITS
V
V
mA
mA
mA
μA
μA
μA
2
_______________________________________________________________________________________
Low-Power Triple-Output TFT LCD DC-DC
Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +3.0V,
SHDN
= IN, V
SUPP
= V
SUPN
= +10V, TGND = PGND = GND, C
REF
= 0.22µF, C
INTG
= 2200pF,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Operating Frequency
FBP Regulation Voltage
FBP Input Bias Current
DRVP PCH On-Resistance
DRVP NCH On-Resistance
FBP Power-Ready Trip Level
FBP Fault Trip Level
Maximum RMS DRVP Current
NEGATIVE CHARGE PUMP
V
SUPN
Input Supply Range
Operating Frequency
FBN Regulation Voltage
FBN Input Bias Current
DRVN PCH On-Resistance
DRVN NCH On-Resistance
FBN Power-Ready Trip Level
FBN Fault Trip Level
Maximum RMS DRVN Current
REFERENCE
Reference Voltage
Reference Undervoltage
Threshold
LOGIC SIGNALS
SHDN
Input Low Voltage
SHDN
Input High Voltage
SHDN
Input Current
RDY
Output Low Voltage
RDY
Output High Voltage
I
SHDN
I
SINK
= 2mA
V
RDY
= +13V
V
REF
-2µA < I
REF
< 50µA
V
REF
rising
1.231
0.9
1.25
1.05
1.269
1.2
V
V
V
FBN
I
FBN
-50
-50
V
SUPN
2.7
0.5
×
f
OSC
0
3
1.5
20
80
120
140
0.1
165
V
FBN
= -0.05V
V
FBN
= +0.050V
V
FBN
= -0.050V
Falling edge
Rising edge
50
50
10
5
13
V
Hz
mV
nA
Ω
Ω
kΩ
mV
mV
A
V
FBP
I
FBP
1.20
-50
SYMBOL
CONDITIONS
MIN
TYP
0.5
×
f
OSC
1.25
3
V
FBP
= +1.200V
V
FBP
= +1.300V
Rising edge
Falling edge
20
1.09
1.13
1.11
0.1
1.16
1.5
V
FBP
= +1.5V
1.30
50
10
5
MAX
UNITS
Hz
V
nA
Ω
Ω
kΩ
V
V
A
MAX1779
0.25V hysteresis (typ)
2.1
0.01
0.25
0.01
0.9
1
0.5
1
V
V
μA
V
μA
_______________________________________________________________________________________
3
Low-Power Triple-Output TFT LCD DC-DC
Converter
MAX1779
ELECTRICAL CHARACTERISTICS
(V
IN
= +3.0V,
SHDN
= IN, V
SUPP
= V
SUPN
= +10V, TGND = PGND = GND, C
REF
= 0.22µF, C
INTG
= 2200pF,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
Input Supply Range
Input Undervoltage Threshold
IN Quiescent Supply Current
SUPP Quiescent Current
SUPN Quiescent Current
IN Shutdown Current
SUPP Shutdown Current
SUPN Shutdown Current
MAIN BOOST CONVERTER
Output Voltage Range
FB Regulation Voltage
FB Input Bias Current
Operating Frequency
Oscillator Maximum Duty Cycle
LX Switch On-Resistance
LX Leakage Current
LX Current Limit
FB Fault Trip Level
POSITIVE CHARGE PUMP
SUPP Input Supply Range
FBP Regulation Voltage
FBP Input Bias Current
DRVP PCH On-Resistance
DRVP NCH On-Resistance
FBP Power-Ready Trip Level
NEGATIVE CHARGE PUMP
SUPN Input Supply Range
FBN Regulation Voltage
FBN Input Bias Current
DRVN PCH On-Resistance
DRVN NCH On-Resistance
FBN Power-Ready Trip Level
REFERENCE
Reference Voltage
Reference Undervoltage
V
REF
-2µA < I
REF
< 50µA
V
REF
rising
1.223
0.9
1.269
1.2
V
V
V
SUPN
V
FBN
I
FBN
V
FBN
= -0.05V
V
FBN
= +0.050V
V
FBN
= -0.050V
Falling edge
20
80
165
2.7
-50
-50
13
50
50
10
5
V
mV
nA
Ω
Ω
kΩ
mV
V
FBP
= +1.200V
V
FBP
= +1.300V
Rising edge
20
1.09
1.16
V
SUPP
V
FBP
I
FBP
V
FBP
= +1.5V
2.7
1.20
-50
13
1.30
50
10
5
V
V
nA
Ω
Ω
kΩ
V
R
LX(ON)
I
LX
I
LIM
Falling edge
I
LX
= 100mA
V
LX
= +13V
350
1.07
V
MAIN
V
FB
I
FB
f
OSC
V
FB
= +1.25V, INTG = GND
V
IN
1.225
-50
195
79
13
1.271
50
305
92
2.0
20
700
1.14
V
V
nA
kHz
%
Ω
µA
mA
V
SYMBOL
V
IN
V
UVLO
I
IN
I
SUPP
I
SUPN
V
IN
rising, 40mV hysteresis (typ)
V
FB
= V
FBP
= +1.5V, V
FBN
= -0.2V
V
FBP
= +1.5V
V
FBN
= -0.1V
V
SHDN
= 0, V
IN
= +5V
V
SHDN
= 0, V
SUPP
= +13V
V
SHDN
= 0, V
SUPN
= +13V
CONDITIONS
MIN
2.7
2.2
MAX
5.5
2.6
1
0.55
0.55
10
10
10
UNITS
V
V
mA
mA
mA
μA
μA
μA
4
_______________________________________________________________________________________
Low-Power Triple-Output TFT LCD DC-DC
Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +3.0V,
SHDN
= IN, V
SUPP
= V
SUPN
= +10V, TGND = PGND = GND, C
REF
= 0.22µF, C
INTG
= 2200pF,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
LOGIC SIGNALS
SHDN
Input Low Voltage
SHDN
Input High Voltage
SHDN
Input Current
RDY
Output Low Voltage
RDY
Output High Leakage
I
SHDN
I
SINK
= 2mA
V
RDY
= +13V
0.25V hysteresis (typ)
2.1
1
0.5
1
0.9
V
V
μA
V
μA
SYMBOL
CONDITIONS
MIN
MAX
UNITS
MAX1779
Note 1:
Specifications to -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(Circuit of Figure 5, V
IN
= +3.3V, T
A
= +25°C, unless otherwise noted.)
MAIN STEP-UP CONVERTER EFFICIENCY
vs. LOAD CURRENT
(L = 10μH, 5V OUTPUT)
MAX1779-02
MAIN OUTPUT VOLTAGE vs. LOAD CURRENT
(L = 10μH, 5V OUTPUT)
MAX1779-01
MAIN OUTPUT VOLTAGE vs. LOAD CURRENT
(L = 33μH, 5V OUTPUT)
MAX1779-03
5.02
100
V
IN
= +4.2V
V
IN
= +3.0V
5.02
5.01
EFFICIENCY (%)
V
IN
= +3.0V
V
MAIN
(V)
5.00
V
IN
= +4.2V
90
5.01
V
IN
= +3.0V
V
MAIN
(V)
5.00
V
IN
= +4.2V
80
70
4.99
60
FIGURE 6
FIGURE 6
4.99
4.98
0
50
100
I
MAIN
(mA)
150
200
50
0
50
100
I
MAIN
(mA)
150
4.98
200
0
50
100
150
I
MAIN
(mA)
200
FIGURE 5
250
300
MAIN STEP-UP CONVERTER EFFICIENCY
vs. LOAD CURRENT
(L = 33μH, 5V OUTPUT)
MAX1779-04
MAIN OUTPUT VOLTAGE vs. LOAD CURRENT
(L = 33μH, 10V OUTPUT)
MAX1779-05
MAIN STEP-UP CONVERTER EFFICIENCY
vs. LOAD CURRENT
(L = 33μH, 10V OUTPUT)
MAX1779-06
100
V
IN
= +4.2V
V
IN
= +3.0V
10.04
100
V
IN
= +5.5V
V
IN
= +3.3V
80
90
EFFICIENCY (%)
90
EFFICIENCY (%)
10.02
V
MAIN
(V)
V
IN
= +3.3V
V
IN
= +5.0V
80
10.00
70
9.98
60
FIGURE 5
0
50
100
150
I
MAIN
(mA)
200
250
300
FIGURE 5
0
50
I
MAIN
(mA)
100
150
70
60
FIGURE 5
0
50
I
MAIN
(mA)
100
150
50
9.96
50
_______________________________________________________________________________________
5
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