Rainbow Electronics MAX1543 - Manual (Page 9)

MAX1542/MAX1543
TFT LCD DC-to-DC Converter with
Operational Amplifiers
_______________________________________________________________________________________ 9
Typical Operating Characteristics (continued)
(V IN = 3.3V, V MAIN = 8V, f OSC = 1.2MHz, T A = +25°C, unless otherwise noted.)
OPERATIONAL AMPLIFIER
SMALL-SIGNAL STEP RESPONSE
MAX1542 toc24
200ns/div
POS_
50mV/div
AC-COUPLED
OUT_
50mV/div
AC-COUPLED
V SUP = 8V, A V = 1
CH2 + OVER
6.234%
CH2 - OVER
2.352%
OPERATIONAL AMPLIFIER
LARGE-SIGNAL STEP RESPONSE
MAX1542 toc23
1 µs/div
V OUT_
1V/div
CHI AMPL
4.86V
CHI + OVER
4.970%
A V = 1
Pin Description
PIN
MAX1542 MAX1543
NAME FUNCTION
1 1 COM
Internal High-Voltage MOSFET Switch Common Terminal. Do not allow the voltage on
COM to exceed V
SRC .
2 2 SRC
Switch Input. Source of the internal high-voltage P-channel MOSFET. Bypass SRC to
PGND with a minimum of 0.1µF close to the pins.
3, 15, 20 — N.C. No Connection. Not internally connected.
— 3 I.C. Internal Connection. Make no connection to this pin.
4 4 PGND
Power Ground. PGND is the source of the main boost N-channel power MOSFET. Connect
PGND to the output capacitor ground terminals through a short, wide PC board trace.
Connect to analog ground (AGND) underneath the IC.
5 5 AGND Analog Ground. Connect to power ground (PGND) underneath the IC.
6 6 POS1 Operational Amplifier 1 Noninverting Input
7 7 NEG1 Operational Amplifier 1 Inverting Input
8 8 OUT1 Operational Amplifier 1 Output
9 9 OUT2 Operational Amplifier 2 Output
10 10 NEG2 Operational Amplifier 2 Inverting Input
11 11 POS2 Operational Amplifier 2 Noninverting Input
12 12 SUP
Operational Amplifier Power Input. Positive supply rail for the OUT1 and OUT2 amplifiers.
Typically connected to V
MAIN . Bypass SUP to AGND with a 0.1µF capacitor.
13 13 LX
Power MOSFET N-Channel Drain and Switching Node. Connect the inductor and catch
diode to LX and minimize the trace area for lowest EMI.