HV9110/HV9112/HV9113
Detailed Description (continued)
Error Amplifier
Remote Shutdown
The error amplifier in the HV911X is a true low-power differential
inputoperationalamplifierintendedforaround-the-amplifiercom-
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.
The shutdown and reset pins of the 911X can be used to perform
either latching or non-latching shutdown of a converter as re-
quired. 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 VDD
.
Output Buffer
The output buffer of the HV911X 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.
Current Sense Comparators
The HV911X uses a true dual comparator system with indepen-
dent comparators for modulation and current limiting. This allows
thedesignergreaterlatitudeincompensationdesign,asthereare
noclamps(exceptESDprotection)onthecompensationpin. Like
the error amplifier, the comparators are of low-noise BiCMOS
construction.
Pinout
1
2
3
4
5
6
7
14
13
12
11
10
9
BIAS
+VIN
FB
COMP
Reset
18
17
16
15
14
Sense
Output
–VIN
Shutdown
VREF
19
FB
13 NC
BIAS 20
Discharge
12
11
10
9
VDD
Discharge
OSC In
NC
NC
OSC In
OSC Out
VDD
1
2
3
•
8
OSC Out
14 Pin SOIC/DIP Package
+VIN
4
5
6
7
8
20-pin PJ Package
top view
11/12/01
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 • FAX: (408) 222-4895
www.supertex.com
©2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
7
SUPERTEX [ Supertex, Inc ]
