EL7563 INTERSIL [Intersil Corporation], EL7563 Datasheet - Page 11

• Manufacturer Part Number: EL7563
• Description: Monolithic 4 Amp DC:DC Step-Down Regulator
• Manufacturer: INTERSIL [Intersil Corporation]

Reference
A 1.5% temperature compensated bandgap reference is
integrated in the EL7563. The external V
as the dominant pole of the amplifier and can be increased
in size to maximize transient noise rejection. A value of
0.1µF is recommended.
Oscillator
The system clock is generated by an internal relaxation
oscillator with a maximum duty-cycle of approximately 95%.
Operating frequency can be adjusted through the C
or can be driven by an external source. If the oscillator is
driven by an external source care must be taken in selecting
the ramp amplitude. Since C
C
C
gain of the system.
When external synchronization is required, always choose
C
lower than that of sync source to accommodate component
and temperature variations. Figure 22 shows a typical
connection.
OSCILLATOR
OSC
SLOPE
OSC
EXTERNAL
ramp, changes to C
such that the free-running frequency is at least 20%
FIGURE 22. OSCILLATOR SYNCHRONIZATION
compensation ramp which determine the open-loop
100pF
OSC
SLOPE
11
390pF
BAT54S
ramp will change the
value is derived from the
10
REF
1
2
3
5
6
7
8
9
capacitor acts
EL7563
OSC
pin
20
19
18
16
15
14
13
12
11
EL7563
Junction Temperature Sensor
An internal temperature sensor continuously monitors die
temperature. In the event that die temperature exceeds the
thermal trip-point, the system is in fault state and will be shut
down. The upper and low trip-points are set to 135°C and
115°C respectively.
The VTJ pin is an accurate indication of the internal silicon
junction temperature (see performance curve.) The junction
temperature T
relation:
Where VTJ is the voltage at VTJ pin in volts.
Power Good and Power On Reset
During power up the output regulator will be disabled until
V
hysteresis is present to eliminate noise-induced
oscillations.
Under-voltage and over-voltage conditions on the regulator
output are detected through an internal window comparator.
A logic high on the PG output indicates that the regulated
output voltage is within about +10% of the nominal selected
output voltage.
T
IN
J
=
reaches a value of approximately 2.9V. About 300mV
75
+
1.2 VTJ
-------------------------
0.00384
–
J
(°C) can be deducted from the following
May 13, 2005
FN7296.2