FAN5078 Datasheet, PDF (6/16 Pages) Fairchild Semiconductor – DDR/ACPI Regulator Combo

Pin Definitions (Continued)
Pin
15
16
17
18
19,
P1
20
21
22
23
24
Pin
Name
3.3
ALW
S3#O
S3#I
EN
GND
ILIM
SS
COMP
FB
REF IN
Pin Function Description
3.3V LDO Output. Internal LDO output. Turned off in S0, on in S5 or S3.
S3#O Output. Open drain output which pulls the gate of the N-Channel blocking MOSFETs low in S5
and S3. This pin goes high (open) in S0.
S3 Input. When LOW, turns off VTT and turns on the 3.3V regulator. Also causes S3#O to pull low to
turn off blocking switch Q3, as shown in Figure 1. PGOOD is low when S3#I is LOW.
ENABLE Typically tied to the system logic signal S5#. When this pin is low, the IC is in a low quiescent
current state, all regulators are off and S3#O is low.
GROUND for the IC is tied to this pin and is also connected to P1.
Current Limit. A resistor from this pin to GND sets the current limit.
Soft Start. A capacitor from this pin to GND programs the slew rate of the PWM and all LDOs during
initialization and transitions between states.
COMP Output of the PWM error amplifier. Connect compensation network between this pin and FB.
VDDQ Feedback. The feedback from PWM output. Used for regulation as well as PGOOD, under-
voltage, and over-voltage protection and monitoring.
VTT Reference. Input that provides the reference for the VTT regulator. A precision internal divider from
VDDQ IN (which can be overridden with external resistors) is provided.
Absolute Maximum Ratings
The Absolute Maximum Ratings are those values beyond which the safety of the device cannot be guaranteed. The device
should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at
the absolute maximum ratings. The Recommended Operating Conditions table defines the conditions for actual device operation.
Parameter
VCC
SW, ISNS, HDRV, S3#O,
BOOT to SW
SW, ISNS, HDRV to PGND
All Other Pins
Junction Temperature (TJ )
Storage Temperature
Lead Soldering Temperature, 10 seconds
I(VTT) Peak (Duration < 2mS)
I(VTT) RMS
Continuous
Transient (t < 100nS)
Recommended Operating Conditions
Min.
-1
-5
-0.3
-20
-65
-1.5
-1.0
Max.
6.5
28
6.5
20
20
-0.3
-20
-65
+1.5
+1.0
Units
V
V
V
V
V
V
°C
°C
°C
A
A
Parameter
Supply Voltage VCC
I(3.3 ALW)
Ambient Temperature (TA )
Conditions
Min.
4.5
-10
Typ.
5
Max.
5.5
1.25
85
Units
V
A
°C
© 2006 Fairchild Semiconductor Corporation
6
FAN5078 Rev. 1.0.0 • 05/11/06
www.fairchildsemi.com