MAX16928EVKIT# Maxim Integrated, MAX16928EVKIT# Datasheet - Page 8

• Manufacturer Part Number: MAX16928EVKIT#
• Description: Power Management IC Development Tools Eval Kit MAX16928 (Complete Automotive TFT-LCD Display Power Supply)
• Manufacturer: Maxim Integrated
• Series: MAX16928r

The MAX16928 is a highly integrated power supply for
automotive TFT-LCD applications. The device integrates
one boost converter, one 1.8V/3.3V regulator controller,
one positive-gate voltage regulator, and one negative-
gate voltage regulator.
The device achieves enhanced EMI performance through
spread-spectrum modulation. Digital input control allows
the device to be placed in a low-current shutdown mode
and provides flexible sequencing of the gate voltage
regulators.
Internal thermal shutdown circuitry protects the device
from overheating. The device is designed to shut down
when its die temperature reaches +165NC (typ) and to
resume normal operation once its die temperature has
fallen 15NC.
The device is factory-trimmed to provide a variety of
power options to meet the most common automotive
TFT-LCD display power requirements, as outlined in the
Ordering Information
Maxim Integrated
PIN
13
14
15
16
17
18
19
20
—
Automotive TFT-LCD Power Supply with Boost
COMPI
NAME
DRVN
FBGH
FBGL
GND
SEQ
REF
GH
EP
table.
Detailed Description
Positive-Gate Voltage Regulator Output
Negative-Gate Voltage Regulator Driver Output. DRVN is the open drain of an internal p-channel FET.
Connect DRVN to the base of an external npn pass transistor.
Analog Ground
Boost Slope Compensation Connection. Connect a capacitor between COMPI and GND to set the
slope compensation.
Positive-Gate Voltage Regulator Feedback Input. FBGH is regulated to 1V. Connect FBGH to the center
of a resistive divider connected between GH and GND.
Negative-Gate Voltage Regulator Feedback Input. FBGL is regulated to 0.25V. Connect FBGL to the
center of a resistive divider connected between REF and the output of the negative-gate voltage
regulator.
1.25V Reference Output. Bypass REF to GND with a 0.1FF ceramic capacitor.
Sequencing Input. SEQ has an internal 500kI pulldown resistor. SEQ determines the sequence in
which V
Exposed Pad. Connect to a large contiguous copper ground plane for optimal heat dissipation. Do not
use EP as the only electrical ground connection.
Converter and Gate Voltage Regulators
GH
and V
GL
power up. See Table 1 for supply sequencing options.
The boost converter employs a current-mode, fixed-
frequency PWM architecture to maximize loop bandwidth
and provide fast transient response to pulsed loads
typical of TFT-LCD panel source drivers. The 2.2MHz
switching frequency allows the use of low-profile induc-
tors and ceramic capacitors to minimize the thickness
of LCD panel designs. The integrated low on-resistance
MOSFET and the device’s built-in digital soft-start func-
tions reduce the number of external components required
while controlling inrush currents. The output voltage
can be set from V
voltage-divider. The regulator controls the output voltage
by modulating the duty cycle (D) of the internal power
MOSFET in each switching cycle. The duty cycle of the
MOSFET is approximated by:
where V
output voltage), and E is the efficiency of the boost con-
verter as shown in the
FUNCTION
INA
is the voltage at INA, V
Pin Description (continued)
INA
D =1
Typical Operating
to 18V with an external resistive
−
η
V
V
INA
O
MAX16928
Boost Converter
O
= V
Characteristics.
SH
(the boost
8