EL7564CREZ Intersil, EL7564CREZ Datasheet - Page 11

• Manufacturer Part Number: EL7564CREZ
• Description: IC REG DC/DC STEP-DN 4A 28HTSSOP
• Manufacturer: Intersil
• Type: Step-Down (Buck)r

Specifications of EL7564CREZ

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1 ~ 3.8 V
• Current - Output: 4A
• Frequency - Switching: 1MHz
• Voltage - Input: 4.5 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
• Power - Output: 13W
• Primary Input Voltage: 5V
• No. Of Outputs: 1
• Output Voltage: 3.8V
• Output Current: 4A
• No. Of Pins: 28
• Operating Temperature Range: -40°C To +85°C
• Current Rating: 4A
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

NMOS Power FETs and Drive Circuitry
The EL7564 integrates low on-resistance (30mΩ) NMOS
FETs to achieve high efficiency at 4A. In order to use an
NMOS switch for the high-side drive it is necessary to drive
the gate voltage above the source voltage (L
accomplished by bootstrapping the V
voltage with an external capacitor C
and diode. When the low-side switch is turned on and the
L
charged through an internal switch to V
the beginning of the next cycle the high-side switch turns
on and the L
As the L
follows and eventually reaches a value of V
typically 10V, for V
level shifted and used to drive the gate of the high-side
FET, via the V
recommended.
Reference
A 1.5% temperature compensated bandgap reference is
integrated in the EL7564. 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 C
X
voltage is close to GND potential, capacitor C
X
pin rises the positive plate of capacitor C
X
HI
pins begin to rise from GND to V
pin. A value of 0.22µF for C
DRV
= V
IN
11
= 5V. This voltage is then
OSCILLATOR
EXTERNAL
VHI
HI
DRV
pin above the L
and internal switch
REF
FIGURE 23. OSCILLATOR SYNCHRONIZATION
, typically 5V. At
DRV
VHI
capacitor acts
X
). This is
IN
OSC
+ V
is
VHI
potential.
VHI
.
IN
is
,
100pF
X
EL7564
BAT54S
390pF
When external synchronization is required, always choose
C
lower than that of the sync source to accommodate
component and temperature variations. Figure 21 shows a
typical connection.
Junction Temperature Sensor
An internal temperature sensor continuously monitors die
temperature. In the event that the die temperature exceeds
the thermal trip-point, the system is in a fault state and will
be shut down. The upper and low trip-points are set to 135°C
and 115°C respectively.
The V
junction temperature (see performance curve.) The junction
temperature T
relation:
Where V
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
T
J
IN
OSC
=
reaches a value of approximately 4V. About 500mV
75
10
TJ
1
2
3
5
6
7
8
9
such that the free-running frequency is at least 20%
+
TJ
pin is an accurate indication of the internal silicon
1.2 VTJ
-------------------------
0.00384
is the voltage at the V
EL7564
–
J
(°C) can be determined from the following
20
19
18
16
15
14
13
12
11
TJ
pin in volts.
May 9, 2005
FN7297.3