MAX749EPA Maxim Integrated Products, MAX749EPA Datasheet - Page 4

• Manufacturer Part Number: MAX749EPA
• Description: Display Drivers Digitally Adjustable able LCD Bias Supply
• Manufacturer: Maxim Integrated Products

Digitally Adjustable LCD Bias Supply
(T
______________________________________________________________Pin Description
4
____________________________Typical Operating Characteristics (continued)
A
= +25°C, L = 47µH, unless otherwise noted.)
PIN
1
2
3
4
5
6
7
8
______________________________________________________________________________________
CURRENT
VOLTAGE
OUTPUT
LOAD
V
TRANSISTOR = ZTX750
OUT
V
TRANSISTOR = ZTX750
NAME
DLOW
OUT
CTRL
GND
ADJ
LOAD-TRANSIENT RESPONSE
DHI
V+
FB
CS
= -15V
= -15V
50 s/div
+2V to +6V Input Voltage to power the MAX749 and external circuitry. When using an external
P-channel MOSFET, V+ must exceed the MOSFET’s gate threshold voltage.
Logic Input. When CTRL is high, a rising edge on ADJ increments an internal counter. When CTRL is
low, the counter is reset to mid-scale when ADJ is high. When ADJ is low, the counter does not
change (regardless of activity on CTRL) as long as V+ is applied.
Logic Input. When CTRL and ADJ are low, the MAX749 is shut down, but the counter is not reset.
When CTRL is low, the counter is reset to mid-scale when ADJ is high. The device is always on when
CTRL is high.
Feedback Input for output full-scale voltage selection. -V
connected from FB to -V
Ground
Output Driver Low. Connect to DHI when using an external P-channel MOSFET. When using an
external PNP transistor, connect a resistor R
mum base-drive current.
Output Driver High. Connect to the gate of the external P-channel transistor, or to the base of the
external PNP transistor.
Current-Sense Input. The external transistor is turned off when current through the sense resistor,
R
SENSE
, brings CS below V+ by 140mV (typ).
100mV
10mA/div
0mA
AC
OUT
/div
. The device is in regulation when V
FUNCTION
BASE
VOLTAGE
VOLTAGE
OUTPUT
INPUT
from DLOW to the base of the PNP to set the maxi-
V
I
TRANSISTOR = ZTX750
LOAD
OUT
= -15V
LINE-TRANSIENT RESPONSE
= 5mA
OUT(MAX)
FB
= (R
50ms/div
= 0V.
FB
) x (20µA) where R
100mV
1 V/div
0V
FB
AC
is
/div