HV9123 Supertex, Inc., HV9123 Datasheet - Page 7

• Manufacturer Part Number: HV9123
• Description: Switchmode PWM Controller
• Manufacturer: Supertex, Inc.

Detailed Description
Error Amplifier
The error amplifier in the HV912x is a true low-power differential
input operational amplifier intended for around-the-amplifier com-
pensation. It is of mixed CMOS-bipolar construction: A PMOS
input stage is used so the common-mode range includes ground
and the input impedance is very high. This is followed by bipolar
gain stages which provide high gain without the electrical noise of
all-MOS amplifiers. The amplifier is unity-gain stable.
Current Sense Comparators
The HV912x uses a true dual comparator system with indepen-
dent comparators for modulation and current limiting. This allows
the designer greater latitude in compensation design, as there are
no clamps (except ESD protection) on the compensation pin. Like
the error amplifier, the comparators are of low-noise BiCMOS
construction.
Pinout
©2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
OSC Out
OSC Out
Output
Output
Sense
Sense
+V
–V
+V
–V
V
V
NC
NC
DD
DD
IN
IN
IN
IN
Note: Pins 2 and 3 are removed
1
2
3
4
5
6
7
8
1
4
5
6
7
8
16 Pin Dip Package
16 Pin SOIC
top view
top view
(continued)
9
16
15
14
13
12
11
10
16
15
14
13
12
11
10
9
BIAS
FB
COMP
Reset
Shutdown
V
Discharge
OSC In
BIAS
FB
COMP
Reset
Shutdown
V
Discharge
OSC In
REF
REF
7
Remote Shutdown
The shutdown and reset pins of the HV912x can be used to
perform either latching or non-latching shutdown of a converter as
required. These pins have internal current source pull-ups so they
can be driven from open-drain logic. When not used they should
be left open, or connected to V
Output Buffer
The output buffer of the HV912x is of standard CMOS construc-
tion (P-channel pull-up, N-channel pull-down). Thus the body-
drain diodes of the output stage can be used for spike clipping if
necessary, and external Schottky diode clamping of the output is
not required.
BIAS
+V
NC
NC
FB
IN
19
20
1
2
3
•
18
4
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: [phone] • FAX: [phone]
20-pin PJ Package
17
5
top view
16
6
DD
.
15
7
14
8
www.supertex.com
HV9120/HV9123
13
12
11
10
9
NC
Discharge
OSC In
OSC Out
V
DD
11/12/01