el7558d Intersil Corporation, el7558d Datasheet - Page 7

• Manufacturer Part Number: el7558d
• Description: Integrated Adjustable 8 Amp Synchronous Switcher
• Manufacturer: Intersil Corporation

Pin Descriptions
I = INPUT, O = OUTPUT, S = SUPPLY
Typical Performance Curves
PIN NUMBER
10
11
12
13
14
15
16
17
18
19
20
1
2
3
4
5
6
7
8
9
PIN NAME
VCC2DET
CSLOPE
PWRGD
OUTEN
COSC
CREF
VSSP
VSSP
VSSP
VSSP
VSSP
VSSP
VSSP
TEST
VDD
FB1
VIN
VIN
OT
LX
7
TYPE
PIN
S
S
S
S
S
S
S
S
O
O
S
S
O
I
I
I
I
I
I
I
Voltage feedback pin for the buck regulator. Active when VCC2DET is logic low. Normally connected
to external resistor divider between VOUT and GND. A 2µA pull-up current forces VOUT to VSS in the
event that FB1is floating and VCC2DET is inadvertently connected to GND.
Bandgap reference bypass capacitor. Typically 0.1µF to VSS.
Slope compensation capacitor. Ramp width corresponds to LX duty cycle. C
normally 1:1.5.
Oscillator timing capacitor. F
Farads.
Power Supply for PWM control circuitry. Normally the same potential as VIN.
Power supply for the buck regulator. Connected to the drain of the high-side NMOS FET.
Ground return for the buck regulator. Connected to the source of the low-side synchronous NMOS
FET.
Same as pin 6.
Same as pin 7.
Same as pin 7.
Same as pin 7.
Same as pin 7.
VCC2DET interface logic input. When driven to logic 1 V
PWM uses FB1 to determine V
The switching regulator output is enabled when logic 1. The reference voltage output operates
whenever the power supply is qualified (VDD>VPOR) regardless of the state of this pin.
Over temperature indicator. Normally high. Pulls low when die temperature exceeds 135°C, returns to
the high state when die temperature has cooled to 100°C.
Power good window comparator output. Logic 1 when regulator output is within ±10% of programmed
voltage.
Test pin. Must be connected to VSSP in normal operation.
Same as pin 7.
Same as pin 7.
Inductor drive pin. High current switching output whose average voltage equals the regulator output
voltage.
(Continued)
2.3
2.1
1.9
1.7
1.5
1.3
1.1
0.9
0.7
200
Minimum Output Voltage vs F
T
J
=120°C
400
EL7558D
F
V
OSC
DD
OSC
600
OSC
=5V
(kHz)
OUT
(Hz) can be approximated by: F
: V
OUT
V
V
DD
DD
800
=5.5V
=4.5V
= 1.0V*(1+R3/R4).
FUNCTION
1000
OUT
= 3.500V. When driven to logic 0 the
OSC
(Hz) = 0.0001/C
SLOPE
to C
OSC
OSC
. C
ratio is
OSC
in