SS6580 Datasheet, PDF (6/8 Pages) Silicon Standard Corp. – Step-Down DC/DC Controller with Shutdown

SS6580/L
n BLOCK DIAGRAM
SD
Built-In Soft Start
Over Current
-
+
200µA
PHASE
OCSET
Power-On
Reset
VCC
FB
COMP
+
PWM Comparator
-
+
Gate Control
REF
Error AMP
-
Oscillator
UGATE
GND
n PIN DESCRIPTIONS
PIN 1: OCSET - Current limit sense pin. Connect a
resistor R_OCSET from this pin to the
drain of the external MOSFET.
R_OCSET, an internal 200µA current
source (I_OCSET), and the external
MOSFET on-resistance (R_DS(ON))
jointly set the over-current trip point
according to the following
equation:
IPEAK = ^{IOCSET × ROCSET}
RDS(ON)
If the FB pin voltage is sensed to
be below 50% of the internal
voltage reference VDAC, the
over-current comparator cycles the
soft-start function.
PIN 2: SD
- Shutdown pin. Connect this pin to
ground for shutdown.
PIN 3:COMP
- External compensation pin. This
pin is connected to the error
amplifier output and PWM
comparator. An RC network is
connected to the FB pin to
compensate the voltage-control
feedback loop of the converter.
PIN 4: FB
- The error amplifier inverting input
pin. The FB pin and COMP pin are
used to compensate the
voltage-control feedback loop.
PIN 5: GND - Ground pin.
PIN 6: PHASE - Over-current detection pin.
Connect the PHASE pin to the
source of the external N-MOSFET.
This pin detects the voltage drop
across the MOSFET R_DS(ON) for
over-current protection.
PIN 7: UGATE - External MOSFET gate drive pin.
Connect this pin to the gate of the
external MOSFET.
PIN 8: VCC
- The chip power supply pin.
Recommended supply voltage is
12V.
Rev.2.01 6/26/2003
www.SiliconStandard.com
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