TDA9109 STMicroelectronics, TDA9109 Datasheet - Page 24

• Manufacturer Part Number: TDA9109
• Description: Multimedia Misc DISC BY STM 11/99
• Manufacturer: STMicroelectronics
• Type: Low Cost Deflection Processorr

Specifications of TDA9109

• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: Through Hole
• Package / Case: SPDIP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TDA9109/S
OPERATING DESCRIPTION (continued)
IV - DC/DC CONVERTER PART
This unit controls the switch-mode DC/DC con-
verter. It converts a DC constant voltage into the
B+ voltage (roughly proportional to the horizontal
frequency) necessary for the horizontal scanning.
ThisDC/DC converter must be configured in step-
up mode. It operates very similarly to the well
known UC3842.
IV.1 - Step-up Mode
Operating Description
- The power MOS is switched-on at the middle of
- The power MOS is switched-off when its current
- The feedback (coming either from the EHV or
Figure 17 : DC/DC Converter
24/30
DAC
7bits
the horizontal flyback.
reaches a predetermined value. For this purpose,
a sense resistor is inserted in its source. The
voltage on this resistor is sent to Pin16 (I
from the flyback) is divided to a voltage close to
8V
I
2
4.8V ±20%
C
22k W
15
± I
REGIN
SMPS
adjust
Inhibit
95dB
A
1MW
Start
Soft
V
B+
+
14
COMP
1.2V
S
L
SENSE
1.2V
I
SENSE
1/3
16
).
C2
C3
Main Features
- Switching synchronized on the horizontal fre-
- B+ voltage always higher than the DC source,
- Current limited on a pulse-by-pulse basis.
The DC/DC converter is disabled :
- when V
- when X-Ray protection is latched,
- directly through I
When disabled, BOUT is driven to GND by a 0.5mA
current source. This feature allows to implement
externally a soft start circuit.
4.8V and compared to the internal 4.8V reference
(I
amplifier, the output of which controls the power
MOS switch-off current.
quency,
VREF
). The difference is amplified by an error
CC
400ns
or V
DD
S
R
2
C bus.
are too low,
Inhibit SMPS
Q
TDA9109/S
BOUT
28
12V