EL7558BCM Просмотр технического описания (PDF) - Intersil
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EL7558BCM Datasheet PDF : 11 Pages
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EL7558B
Typical Performance Curves (Continued)
Minimum Output Voltage vs FOSC
2.3
2.1 TJ=120°C
1.9
VDD=5.5V
1.7
VDD=5V
1.5
1.3
1.1
VDD=4.5V
0.9
0.7
200
400
600
800
FOSC (kHz)
1000
Pin Descriptions
I = INPUT, O = OUTPUT, S = SUPPLY
PIN NUMBER
1
PIN NAME
FB1
PIN
TYPE
I
2
CREF
I
3
CSLOPE
I
4
COSC
I
5
VDD
S
6
VIN
S
7
VSSP
S
8
VIN
S
9
VSSP
S
10
VSSP
S
11
VSSP
S
12
VSSP
S
13
VCC2DET
I
14
OUTEN
I
15
OT
O
16
PWRGD
O
17
TEST
I
18
VSSP
S
19
VSSP
S
20
LX
O
FUNCTION
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. CSLOPE to COSC ratio is
normally 1:1.5.
Oscillator timing capacitor. FOSC (Hz) can be approximated by: FOSC (Hz) = 0.0001/COSC. COSC in
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 VOUT = 3.500V. When driven to logic 0 the
PWM uses FB1 to determine VOUT: VOUT = 1.0V*(1+R3/R4).
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.
7
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