Keysight 9000 Series Service Manual page 126

Chapter 7: Theory of Operation
Block-Level Theory
Figure 7-1
+5V
(3%)
Over current
protection
PC
OCx PSWx
mother
USB
b oard
1. 2V/2 .5(dig ital)
Analo g
signal
Digital
sig nal
USB
3. 3V(analog)
3.3V (d igital)
5V(analog )
5 V(digital)
12V(analo g)
Disk Drive
The hard disk drive is a high-capacity, shock-resistant unit. It is used to store the oscilloscope's operating
system and certain system configuration data.
The drive can also be used to store and recall oscilloscope setups and waveforms.
126
Keyboard block diagram with key components
version 4.0 04 /24 /2 007
Vref
Line pro tection
USB1
USB HUB
ISP1521
I2C GPIO
PCA95 54
+12
+Vp/-Vp
regulator
-12
+Vp -Vp
Rprog
-Vp +Vp offset data
Encoder
Matrix(14)
(4x4)
3.3V
Reset (RC0 )
Port E
RA3
SPP
RA6/CLK
co ntrol
Micro-controller
(4 bits)
4
PIC18F4455
8
Port D
(8 bits)
RC4
RC5
OSC1
RB0 RB1
SDATA SCL
AD C
. .
I2 C Mux
PCA9544
. .
16bit DAC
Autoprobe
Autoprobe
DAC8534
I2C
Interface
Interface
Probe ID
Voltage to
data clock
Rid clo ck Rp rog -12V +12V
A DC: RA0 , RA1, RA2,
Push Button(22)
RA5
Matrix
Caloffset: RB2, RB5,
(3x8)
RB6 , RB7
Scannin g matrix
Matrix
2 4
FPGA FPGA
XC3S100 XC3S100
8 LED
Sh ift
regis ter
8
5 .0V Regul at or
LM1 117 3 .0V
Vo ltage
divider
5.0V
Regul at or
LT 123 6
2. 5V 3 .3V
.
Vo ltage Vo ltage
divider div ider
To PIC
current
offset
LED
(24
LED)