EL7584IRZ-T13 Intersil, EL7584IRZ-T13 Datasheet - Page 13

• Manufacturer Part Number: EL7584IRZ-T13
• Description: IC CONV DC/DC 4-CHAN 24-TSSOP
• Manufacturer: Intersil

Specifications of EL7584IRZ-T13

• Applications: Converter, TFT, LCD
• Voltage - Input: 2 ~ 14 V
• Number Of Outputs: 2
• Voltage - Output: 5 ~ 17 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Two-Stage Negative Charge Pump Circuit
The maximum V
R
where V
The V
The V
back plane of an LCD display. This plane is capacitively
coupled to the pixel drive voltage which alternately cycles
positive and negative at the line rate for the display. Thus the
amplifier must be capable of sourcing and sinking capacitive
pulses of current, which can occasionally be quite large (a
few 100mA for typical applications).
The use of the V
a voltage, corresponding to the mid-DAC potential, is
generated by a resistive divider and buffered by the
amplifier. The amplifier's stability is designed to be
dominated by the load capacitance, thus for very short
duration pulses (< 1µs) the output capacitor supplies the
current. For longer pulses the V
current. By virtue of its high transconductance which
progressively increases as more current is drawn, it can
maintain regulation within 5mV as currents up to 50mA are
drawn, while consuming only 1.5mA of quiescent current.
V
V
V
21
OFF
OFF
DDN
and R
(
COM
max
=
- N
COM
REF
-V
×
22
)
REF
buffer is designed to control the voltage on the
V
≥
Buffer
LX
is 1.310V.
I
determine V
OUT
×
(
max
OFF
COM
R
--------- -
R
21
22
×
2
)
output voltage for N+1 stage charge pump is:
+
×
Buffer is illustrated in Figure 21. Here,
N
(
R
×
OFF
ONN


2
13
×
output voltage:
+
V
COM
R
DIODE
ONP
V
R
R
+
DRVN
V
-
DDN
buffer supplies the
ONP
ONN
SSN
FBN
)
+
+
I
2
OUT
×
V
DIODE
×
--------------------------------------------
0.5
C
CPN
×
5V-17V
- I
F
S
OUT
1
×
C
C
CPN
×
OUT2
EL7584
--------------------------------------------
0.5
+
×
I
F
OUT
S
1
×
If V
voltage by including a zener diode between V
V
As with any high performance buffer, there are several
design issues that must be considered when using the part.
These are summarized below.
Good Decoupling of Power Supplies
This is essential for this component and 1µF ceramic low
ESR decoupling capacitors are recommended. These
should be placed close to the pins.
Choice of Output Capacitor
A 1µF ceramic capacitor with low ESR (X5R or X7R type) is
recommended for this amplifier. This capacitor determines
the stability of the amplifier. Reducing it will make the
amplifier less stable, and should be avoided. With a 1µF
capacitor, the unity gain bandwidth of the amplifier is close to
×
C
DDC
CPN
----------------------------------------------- -
0.5
V
BOOST
LX
C
×
.
FIGURE 21. V
CPN
C
- I
F
OUT2
S
R
R
OUT
1
×
32
31
exceeds 15V, V
C
OUT2
×
----------------------------------------------- - -
0.5
V
×


REF
INC
COM
F
R
R
S
V
21
22
1
×
BOOST
+
-
USED AS A VOLTAGE BUFFER
C
V
OUT2
V
V
DDC
OFF
DDC
SSC
must be protected from over-
0.1µF
V
COM
1µF
CERAMIC
LOW ESR
BOOST
February 4, 2005
V
COM
and
FN7317.2