EVALUATION KIT AVAILABLE
MAX16928
Automotive TFT-LCD Power Supply with Boost
Converter and Gate Voltage Regulators
General Description
The MAX16928 is a highly integrated power supply
for automotive TFT-LCD applications. The device inte-
grates one boost converter, one 1.8V/3.3V regulator
controller, and two gate voltage regulators. The device
comes in several versions to satisfy common automotive
TFT-LCD power-supply requirements (see the
Ordering
Information
table).
The boost converter uses spread-spectrum modulation to
reduce peak interference and to optimize EMI performance.
The sequencing input (SEQ) allows flexible sequencing
of the positive-gate and negative-gate voltage regulators.
The power-good indicator (PGOOD) indicates a failure
on any of the converters or regulator outputs. Integrated
thermal shutdown circuitry protects the device from over-
heating.
The MAX16928 is available in a 20-pin TSSOP pack-
age with exposed pad and operates over the -40NC to
+105NC temperature range.
Features
S
High-Power (Up to 6W) Boost Output Providing Up
to 18V
S
1.8V or 3.3V Regulator Provides 500mA with
External npn Transistor
S
One Positive-Gate Voltage Regulator Capable of
Delivering 20mA at 28V
S
One Negative-Gate Voltage Regulator
S
High-Frequency 2.2MHz Operation
S
Flexible Stand-Alone Sequencing
S
True Shutdown™ Boost Converter
S
Internal Soft-Start
S
Overtemperature Shutdown
S
-40NC to +105NC Operation
S
AEC-Q100 Qualified
Applications
Automotive Dashboards
Automotive Central Information Displays
Automotive Navigation Systems
Ordering Information
appears at end of data sheet.
Typical Operating Circuit
appears at end of data sheet.
True Shutdown is a trademark of Maxim Integrated Products, Inc.
For related parts and recommended products to use with this part, refer to:
www.maximintegrated.com/MAX16928.related
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-5991; Rev 2; 3/13
MAX16928
Automotive TFT-LCD Power Supply with Boost
Converter and Gate Voltage Regulators
ABSOLUTE MAXIMUM RATINGS
INA, COMPV, FBP to GND ......................................-0.3V to +6V
PGOOD to GND ......................................................-0.3V to +6V
CP, GH to GND .....................................................-0.3V to +31V
CP, GH to GND (V
INA
= 3.3V) ..............................-0.3V to +29V
LXP to GND ...........................................................-0.3V to +20V
DRVN to GND........................................................-25V to +0.3V
ENP, DR, FB, GATE, COMPI, FBGH,
FBGL, REF, SEQ to GND .....................-0.3V to (V
INA
+ 0.3V)
GND to PGNDP ....................................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70NC)
TSSOP (derate 26.5mW/NC above +70NC)................2122mW
Operating Temperature Range ........................ -40NC to +105NC
Junction Temperature Range........................... -40NC to +150NC
Storage Temperature Range............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
TSSOP
Junction-to-Ambient Thermal Resistance (B
JA
) .......37.7NC/W
Junction-to-Case Thermal Resistance (B
JC
) .................2NC/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to
www.maximintegrated.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
INA
= 5V, V
GND
= V
PGNDP
= 0V, T
A
= T
J
= -40NC to +105NC, typical values are at T
A
= +25NC unless otherwise noted.) (Note 2)
PARAMETER
INA Input Supply Range
INA Undervoltage Lockout
Threshold
INA Supply Current
INA Shutdown Current
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
Duration to Trigger Fault
Condition
Autoretry Time
REFERENCE (REF)
REF Output Voltage
REF Load Regulation
REF Undervoltage Lockout
Threshold
OSCILLATOR
Spread-Spectrum Factor
SSR
As a percentage of switching frequency,
f
SW
Q4
%
V
REF
No output current
0 < I
REF
< 80FA, REF sourcing
Rising edge, hysteresis = 200mV
1.236
-2
1.25
1.264
+2
1.165
V
%
V
I
INA
I
SHDN
T
SHDN
T
H
V
FBP
, V
FBGH
, or V
FBGL
below its threshold
V
INA
rising, hysteresis = 200mV,
T
A
= +25NC
V
FBP
= V
FBGH
= 1.3V, V
FBGL
= 0V,
LXP not switching
V
ENP
= 0V, T
A
= +25NC
Temperature rising
SYMBOL
CONDITIONS
MIN
3
2.5
2.7
1.5
0.5
+165
15
238
1.9
TYP
MAX
5.5
2.9
2.0
UNITS
V
V
mA
FA
NC
NC
ms
s
BOOST, POSITIVE (GH), NEGATIVE (GL), 1.8V/3.3V CONVERTERS
Maxim Integrated
2
MAX16928
Automotive TFT-LCD Power Supply with Boost
Converter and Gate Voltage Regulators
ELECTRICAL CHARACTERISTICS (continued)
(V
INA
= 5V, V
GND
= V
PGNDP
= 0V, T
A
= T
J
= -40NC to +105NC, typical values are at T
A
= +25NC unless otherwise noted.) (Note 2)
PARAMETER
BOOST CONVERTER
Switching Frequency
Maximum Duty Cycle
Duty cycle = 70%,
C
COMPI
= 220pF
Low boost current-
limit option
High boost current-
limit option
f
SW
1.98
82
0.625
1.25
0.78
A
1.56
110
8.5
30
V
INA
V
INA
= +3V to +5.5V,
0 < I
LOAD
< full load
Measured at FBP
0 < I
LOAD
< full load
V
INA
= +3V to +5.5V
V
FBP
= +1V, T
A
= +25NC
DI
=
Q2.5FA
at COMPV, T
A
= +25NC
400
T
A
= +25NC
T
A
= -40NC to
+105NC
0.985
0.98
0.74
1.0
1.0
0.85
-1
0.1
Q1
18
1.015
1.02
0.96
V
V
%
%/V
FA
FS
1.87
250
20
mI
FA
ms
V
2.20
2.42
93.5
MHz
%
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LXP Current Limit
I
LIM
LXP On-Resistance
LXP Leakage Current
Soft-Start Time
Output Voltage Range
FBP Regulation Voltage
PGOOD Threshold
FBP Load Regulation
FBP Line Regulation
FBP Input Bias Current
FBP to COMPV
Transconductance
R
DS_ON(LXP)
I
LXP
= 200mA
I
LK_LXP
V
LXP
= 20V, T
A
=+25NC
(Note 3)
V
SH
V
FBP
V
PG_FBP
POSITIVE-GATE VOLTAGE REGULATOR (GH)
Output Voltage Range
CP Overvoltage Threshold
FBGH Regulation Voltage
PGOOD Threshold
FBGH Load Regulation
FBGH Line Regulation
FBGH Input Bias Current
GH Output Current
GH Current Limit
GH Soft-Start Time
NEGATIVE-GATE VOLTAGE REGULATOR (GL)
Output Voltage Range
FBGL Regulation Voltage
PGOOD Threshold
V
DRVN
V
FBGL
V
PG_FBGL
I
DRVN
= 100FA
Measured at FBGL
-24
0.212
0.38
0.242
0.4
-2
0.271
0.42
V
V
V
I
GH
I
LIM_GH
V
FBGH
V
PG_FBGH
V
GH
With external charge pump, T
A
= +25NC
(maximum V
CP
= 29.5V)
T
A
= +25NC (Note 4)
I
GH
= 1mA
Measured at FBGH
I
GH
= 0 to 20mA
V
CP
= 12V to 20V at V
GH
= 10V,
I
GH
= 10mA
V
FBGH
= 1V, T
A
= +25NC
V
CP
- V
GH
= 2V
20
35
56
7.45
5
29.5
0.96
0.83
30.5
1.0
0.85
2
2
Q1
1.034
0.87
29
V
V
V
V
%
%
FA
mA
mA
ms
Maxim Integrated
3
MAX16928
Automotive TFT-LCD Power Supply with Boost
Converter and Gate Voltage Regulators
ELECTRICAL CHARACTERISTICS (continued)
(V
INA
= 5V, V
GND
= V
PGNDP
= 0V, T
A
= T
J
= -40NC to +105NC, typical values are at T
A
= +25NC unless otherwise noted.) (Note 2)
PARAMETER
FBGL Input Bias Current
DRVN Source Current
DRVN Source Current Limit
GL Soft-Start Time
1.8V/3.3V REGULATOR CONTROLLER
Output Voltage
V
FB
V
DR
= V
FB
3.3V regulator option
1.8V regulator option
3.3V regulator option,
FB rising
1.8V regulator option,
FB rising
3.18
1.746
2.4
1.364
3.3
1.8
2.57
1.38
2.5
4.5
4.5
6
3.38
1.854
2.7
V
1.396
FA
mA
V
SYMBOL
CONDITIONS
V
FBGL
= +0.25V
V
FBGL
= +0.5V, V
DRVN
= -10V
2
2.5
4
7.45
MIN
TYP
MAX
Q1
UNITS
FA
mA
mA
ms
FB PGOOD Threshold
V
PG_FB
Measured at FB
(Notes 4, 6)
V
FB
= 1.8V
V
FB
= 3.3V
V
FB
= 1.8V
V
GATE
= 0.5V
FB Input Bias Current
DR Drive Current
INPUT SERIES SWITCH CONTROL
p-Channel FET GATE Sink
Current
GATE Voltage Threshold
DIGITAL LOGIC
ENP, SEQ Input Pulldown
Resistor Value
ENP, SEQ Input-Voltage Low
ENP, SEQ Input-Voltage High
PGOOD Leakage Current
PGOOD Output-Voltage Low
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
R
PD
V
IL
V
IH
I
LK_IN
V
OL
33
55
1.25
75
FA
V
Measured at GATE; below this voltage, the
external p-channel FET is considered on
500
0.3 x
V
INA
0.7 x
V
INA
T
A
= +25NC
2mA sink current, T
A
= +25NC
Q1
0.4
kI
V
V
FA
V
Specifications over temperature are guaranteed by design and not production tested.
50% of the soft-start voltage time is due to the soft-start ramp and the other 50% is due to the settling of the output voltage.
After the voltage at CP exceeds this overvoltage threshold, the entire circuit switches off and autoretry is started.
Guaranteed by design; not production tested.
FB power good is indicated by PGOOD. The condition V
FB
< V
PG_FB
does not shut down/restart the device.
Maxim Integrated
4
MAX16928
Automotive TFT-LCD Power Supply with Boost
Converter and Gate Voltage Regulators
Typical Operating Characteristics
(V
INA
= +5V, V
SH
= +12V, V
GH
= +18V, V
GL
= -6V, V
REG
= 3.3V, T
A
= +25NC, unless otherwise noted.)
SHUTDOWN SUPPLY CURRENT
MAX16928 toc01
EFFICIENCY vs. LOAD CURRENT (BOOST)
MAX16928 toc02
LOAD REGULATION (BOOST)
0.8
0.6
0.4
ERROR (%)
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
MAX16928 toc03
10
9
8
SUPPLY CURRENT (nA)
7
6
5
4
3
2
1
0
3.0
3.5
4.0
4.5
5.0
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
1.0
V
INA
= 5V
V
INA
= 3.3V
V
INA
= 3.3V
V
INA
= 5V
0
100
200
300
400
500
600
5.5
0
100
200
300
400
500
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
LOAD CURRENT (A)
LINE REGULATION (BOOST)
MAX16928 toc04
BOOST STARTUP WAVEFORMS
1.0
0.8
0.6
0.4
ERROR (%)
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
3.0
3.5
4.0
4.5
5.0
MAX16928 toc05
V
ENP
5V/div
V
LXP
10V/div
I
LX
1A/div
V
SH
10V/div
5.5
4ms/div
INPUT VOLTAGE (V)
50mA TO 450mA LOAD-TRANSIENT RESPONSE
MAX16928 toc06
SUPPLY SEQUENCING WAVEFORMS
(V
SEQ
= 0V)
MAX16928 toc07
V
ENP
5V/div
450mA
50mA
I
SH
500mA/div
V
GH
5V/div
V
SH
5V/div
V
REG
5V/div
V
GL
5V/div
V
SH
200mV/div
100µs/div
10ms/div
Maxim Integrated
5
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