MAX8726EUE+T Maxim Integrated Products, MAX8726EUE+T Datasheet - Page 9

• Manufacturer Part Number: MAX8726EUE+T
• Description: Display Drivers Triple-Output TFT-LC -LCD DC-DC Converter
• Manufacturer: Maxim Integrated Products

Specifications of MAX8726EUE+T

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

For the main boost regulator, soft-start allows a gradual
increase of the internal current-limit level during startup
to reduce input surge currents. The MAX1748/MAX8726
divide the soft-start period into four phases. During
phase 1, the MAX1748/MAX8726 limit the current limit to
only 0.38A (see the
approximately a quarter of the maximum current limit
(I
1ms, soft-start enters phase II and the current limit is
increased by another 25%. This process is repeated for
phase III. The maximum 1.5A (typ) current limit is
reached at the end of phase III or when the output
reaches regulation, whichever occurs first (see the start-
up waveforms in the Typical Operating Characteristics).
For the charge pumps, soft-start is achieved by control-
ling the rise rate of the output voltage. The output volt-
age regulates within 4ms, regardless of output
capacitance and load, limited only by the regulator’s
output impedance.
Figure 1. PWM Boost Converter Block Diagram
LX(MAX)
). If the output does not reach regulation within
C
INTG
_______________________________________________________________________________________
INTG
Electrical Characteristics tables),
OSC
+
+
-
-
+
MAX1748
MAX8726
S
R
Soft-Start
V
IN
I
LIM
= 2.7V TO 5.5V
Q
Gm
-
+
1.25V
+ -
IN
A logic-low level on SHDN disables all three
MAX1748/MAX8726 converters and the reference.
When shut down, supply current drops to 0.1µA to
maximize battery life and the reference is pulled to
ground. The output capacitance and load current
determine the rate at which each output voltage will
decay. A logic-level high on SHDN power activates the
MAX1748/MAX8726 (see the Power-Up Sequencing
section). Do not leave SHDN floating. If unused,
connect SHDN to IN.
Upon power-up or exiting shutdown, the MAX1748 and
MAX8726 start their respective power-up sequences.
-
Triple-Output TFT-LCD
L1
PGND
GND
REF
LX
FB
DC-DC Converters
C2
D1
Power-Up Sequencing
V
V
R2
R1
OUT
REF
R
COMP
= 1.25V
= [1 + (R1 / R2)] x V
(UP TO 13V)
C1
C
V
MAIN
COMP
REF
Shutdown
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