DELL D400 Schematics

Insert AC adapter only,

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then without press power

button

DP1 (Pebble) Power Sequence

PS_ID

PS_ID is to confirm that insertion of

AC adapter 65W or 90W

Power Plan:

0. RTC power plane.

1. Always power plane.

2. SUS power plane.

3. RUN power plane.

ACPI Power State:

1. S0: System Full On, All power planes are ON.

2. S3: Suspend to RAM, RUN power off.

3. S4: Suspend to Disk, RTC and Always power
ON.(AC)

4. S5: Soft Off, power state like S4.

PWR_SRC

+RTCSRC is generated by

PWR_SRC

through D40

+RTCSRC

U9 U13

Pin 1 Pin 1

+RTCSRC will be input of MAXIM 1615,

then +RTC_PWR is the output of

MAXIM 1615

Pin 3

+RTC_PWR

With either LIVE_ON_BATT or

ACAV_IN existed, +RTC_PWR can

convert to +5VALW through Q61

+5VALW

X7 XTAL 32.768K will

oscillate after
+3.3VRTC comes up
high & U37.2 should
driven high after
+3VALW comes up.

If no ALW power, what
should we do?
A: Check all ACAV_IN
relate circuit.

+RTCSRC will be input of MAXIM 1615,

then +3.3VRTC is the output of MAXIM

1615

Pin 3

+3.3VRTC

With either LIVE_ON_BATT or

ACAV_IN existed, +3.3VRTC can

convert to +3VALW through Q62

+3VALW

Macallen

32 K Hz

Go!

If Macallen is working.

Q: If no debug out pulse?

1. Macallen.

2. BIOS ROM.

CN8 pin2 will have 1,2,3,4
pulse when AC adapter
attached( DEBUG_OUT )

Insert AC adapter only, then

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press power

button

POWER_SW#

DP1 (Pebble) Power Sequence

AUX_EN from

Macallen

After +3VALW , +5VALW,

DEBUG_OUT were all come out.

Macallen should assert SUS_ON.

SUS_ON

SUS_ON and AUX_EN were initial

trigger for MAX1632. It will result in

producing +5VSUS , +3VSRC and

DC_12CV.

+5VSUS

+5VSUS was initial

trigger for SC1486. It

will produce

+2.5VSUS

+3VSRC

Q17

+3VSUS

If Macallen do not driven SUS_ON high

1. Re-heat Macallen.

2. Change one new Macallen.

3. Still no SUS_ON, check BIOS ROM.

DC_12V

Q60

With

RUNPWROK

asserts

+12V

+2.5VSUS

Check All SUS power planes
are in correct voltage level?

SUS_ON

2.5V_PWRGD

+3VSUS was initial

trigger for MAX1644. It

will produce +1.5VSUS.

+1.5VSUS

1632_3VOK

If these three signal

driven high, then through

U74 ( AND gate ) will

produce SUSPWROK

SUSPWROK