MAX1518B Datasheet, PDF (10/25 Pages) Maxim Integrated Products – TFT-LCD DC-DC Converter with Operational Amplifiers

TFT-LCD DC-DC Converter with
Operational Amplifiers
Pin Description (continued)
PIN
NAME
FUNCTION
17
OUT4 Operational-Amplifier 4 Output
18
POS5 Operational-Amplifier 5 Noninverting Input
19
NEG5 Operational-Amplifier 5 Inverting Input
20
OUT5 Operational-Amplifier 5 Output
21
LX
n-Channel Power MOSFET Drain and Switching Node. Connect the inductor and Schottky diode to LX
and minimize the trace area for lowest EMI.
22
IN
Supply Voltage Input. IN can range from 2.6V to 6.5V.
23
FB
Step-Up Regulator Feedback Input. Regulates to 1.236V (nominal). Connect a resistive voltage-divider
from the output (V_MAIN) to FB to analog ground (AGND). Place the divider within 5mm of FB.
24
COMP ^{Step-Up Regulator Error-Amplifier Compensation Point. Connect a series RC from COMP to AGND.}
See the Loop Compensation section for component selection guidelines.
Gate-On Linear-Regulator Feedback Input. FBP regulates to 1.25V (nominal). Connect FBP to the
25
FBP
center of a resistive voltage-divider between the regulator output and AGND to set the gate-on linear-
regulator output voltage. Place the resistive voltage-divider close to the pin.
26
DRVP
Gate-On Linear-Regulator Base Drive. Open drain of an internal n-channel MOSFET. Connect DRVP to
the base of an external pnp pass transistor. See the Pass-Transistor Selection section.
Gate-Off Linear-Regulator Feedback Input. FBN regulates to 250mV (nominal). Connect FBN to the
27
FBN
center of a resistive voltage-divider between the regulator output and REF to set the gate-off linear-
regulator output voltage. Place the resistive voltage-divider close to the pin.
28
DRVN
Gate-Off Linear-Regulator Base Drive. Open drain of an internal p-channel MOSFET. Connect DRVN to
the base of an external npn pass transistor. See the Pass-Transistor Selection section.
29
DEL
High-Voltage Switch Delay Input. Connect a capacitor from DEL to AGND to set the high-voltage
switch startup delay.
High-Voltage Switch Control Input. When CTL is high, the high-voltage switch between COM and SRC
30
CTL
is on and the high-voltage switch between COM and DRN is off. When CTL is low, the high-voltage
switch between COM and SRC is off and the high-voltage switch between COM and DRN is on. CTL is
inhibited by the undervoltage lockout and when the voltage on DEL is less than 1.25V.
31
DRN
Switch Input. Drain of the internal high-voltage back-to-back p-channel MOSFETs connected to COM.
32
COM
Internal High-Voltage MOSFET Switch Common Terminal. Do not allow the voltage on COM to exceed
V_SRC.
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