AIC1569A
BLOCK DIAGRAM
115%
POWER-ON
RESET
OVP
OVP
VCC
+
−
+
−
110%
VSEN
90%
POWER GOOD
PGOOD
+
−
+
−
50%
10µA
+
−
OVER
CURRENT
I
OCS
200µA
OCSET
SS
PHASE
BOOT
4V
UGATE
SOFT
START
REFERENCE
VDAC
CONTROL
LOGIC
VCC
GND
VID0
VID1
VID2
VID3
VID4
FB
COMP
5-BITS DAC
+
−
ERROR AMP
+
−
PWM
COMPARATOR
LGATE
PGND
OSCILLATOR
RT
PIN DESCRIPTIONS
PIN 1: VSEN - Converter output voltage sense
pin. Connect this pin to the
converter output. The PGOOD
and OVP comparator circuits use
this signal to report output voltage
status and perform overvoltage
protection function.
PIN 2: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
OCS
), and the external
MOSFET on-resistance (R
DS(ON)
)
jointly set the over current
trip
point according to the following
equation:
I
PEAK
=
I
OCS
×
R
OCSET
R
DS( ON)
If 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 3:SS
- Soft start pin. Connect a capacitor
from this pin to ground. An internal
10µA current source provides soft
start function for the converter.
5
AIC [ ANALOG INTERGRATIONS CORPORATION ]
