MAX749ESA Ver la hoja de datos (PDF) - Maxim Integrated
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MAX749ESA Datasheet PDF : 12 Pages
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Digitally Adjustable LCD Bias Supply
____________________________Typical Operating Characteristics (continued)
(TA = +25°C, L = 47µH, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
LINE-TRANSIENT RESPONSE
OUTPUT
VOLTAGE
LOAD
CURRENT
VOUT = -15V
TRANSISTOR = ZTX750
50µs/div
VOUT = -15V
TRANSISTOR = ZTX750
100mVAC/div
10mA/div
0mA
OUTPUT
VOLTAGE
INPUT
VOLTAGE
50ms/div
VOUT = -15V
ILOAD = 5mA
TRANSISTOR = ZTX750
100mVAC/div
1 V/div
0V
______________________________________________________________Pin Description
PIN
NAME
FUNCTION
1
V+
+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
2
ADJ
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.
3
CTRL
When CTRL is low, the counter is reset to mid-scale when ADJ is high. The device is always on when
CTRL is high.
4
FB
Feedback Input for output full-scale voltage selection. -VOUT(MAX) = (RFB) x (20µA) where RFB is
connected from FB to -VOUT. The device is in regulation when VFB = 0V.
5
GND
Ground
Output Driver Low. Connect to DHI when using an external P-channel MOSFET. When using an
6
DLOW
external PNP transistor, connect a resistor RBASE from DLOW to the base of the PNP to set the maxi-
mum base-drive current.
7
DHI
Output Driver High. Connect to the gate of the external P-channel transistor, or to the base of the
external PNP transistor.
8
CS
Current-Sense Input. The external transistor is turned off when current through the sense resistor,
RSENSE, brings CS below V+ by 140mV (typ).
4 ______________________________________________________________________________________
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