MAX8752ETA+T Maxim Integrated Products, MAX8752ETA+T Datasheet - Page 8

• Manufacturer Part Number: MAX8752ETA+T
• Description: IC DC-DC CONV TFT LCD 8-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8752ETA+T

• Applications: Converter, TFT, LCD
• Voltage - Input: 1.8 ~ 5.5 V
• Number Of Outputs: 1
• Voltage - Output: 1.8 ~ 13 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

where I
regulator efficiency (85% nominal), and D is the duty
cycle. The duty cycle when operating at the current
limit is:
where V
R
The MAX8752 features bootstrapping operation. In nor-
mal operation, the internal linear regulator supplies
power to the internal circuitry. The input of the linear
regulator (SUP) should be directly connected to the
output of the step-up regulator. After the input voltage
at SUP is above 1.75V, the regulator starts open-loop
switching to generate the supply voltage for the linear
regulator. The internal reference block turns on when
the LDO voltage exceeds 2.7V (typ).
When the reference voltage reaches regulation, the
PWM controller and the current-limit circuit are enabled
and the step-up regulator enters soft-start. During the
soft-start, the main step-up regulator directly limits the
peak inductor current, allowing from zero up to the full
current limit in eight equal current steps. The maximum
load current is available after the output voltage reach-
es regulation (which terminates soft-start), or after the
soft-start timer expires (13ms typ). The soft-start routine
minimizes the inrush current and voltage overshoot and
ensures a well-defined startup behavior.
The MAX8752 shuts down to reduce the supply current
to 0.1µA when SHDN is low. In this mode, the internal ref-
erence, error amplifier, comparators, and biasing circuit-
ry turn off and the n-channel MOSFET is turned off. In
shutdown, the step-up regulator’s output is connected to
IN through the external inductor and rectifier diode.
TFT LCD Step-Up DC-DC Converter
Table 2. Component Suppliers
8
Murata
Sumida
TDK
Toshiba
ON
_______________________________________________________________________________________
is the on-resistance of the internal MOSFET.
LIM
D
DIODE
SUPPLIER
=
is the current limit calculated above, η is the
V
is the rectifier diode forward voltage and
OUT
V
Bootstrapping and Soft-Start
OUT
−
I
LIM
−
V
×
IN
R
+
ON
V
DIODE
+
770-436-1300
847-545-6700
847-803-6100
949-455-2000
V
DIODE
PHONE
Shutdown
Step-up regulators using the MAX8752 can be
designed by performing simple calculations for a first
iteration. All designs should be prototyped and tested
prior to production. Table 1 provides a list of power
components for the typical applications circuit. Table 2
lists component suppliers.
External component value choice is primarily dictated
by the output voltage and the maximum load current,
as well as maximum and minimum input voltages.
Begin by selecting an inductor value. Once the induc-
tor value and peak current are known, choose the
diode and capacitors.
The minimum inductance value, peak current rating,
and series resistance are factors to consider when
selecting the inductor. These factors influence the con-
verter’s efficiency, maximum output load capability,
transient response time, and output voltage ripple.
Physical size and cost are also important factors to
consider.
Table 1. Component List
DESIGNATION
770-436-3030
847-545-6720
847-803-6296
949-859-3963
C1
C2
D1
L1
FAX
Applications Information
10µF ±10%, 4V X5R ceramic capacitor
(0603)
TDK C1608X5R0G106K
Murata GRM188R60G106M
10µF ±10%, 16V X5R ceramic capacitor
(1206)
TDK C3216X5R1C106K
Murata GRM319R61A106K
3A, 30V Schottky diode (M-flat)
Toshiba CRS02
2.6µH, 2.1A power inductor
3.3µH, 1.7A power inductor
Sumida CDRH6D12-3R3
www.murata.com
www.sumida.com
www.component.tdk.com
www.toshiba.com/taec
DESCRIPTION
Inductor Selection
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