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AS998/AS998A
PWM Controller
Electrical Characteristics
Electrical Characteristics are guaranteed over full junction temperature range (0 to 105°C). Ambient temperature must be derated
based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are VDD = 12 V;
OV = 0V, CSNS = 0V. Cload = 1800pf, Creg = 100 nf (AVVD to GND). To start chip, Vdd must be raised above UVLhigh.
Parameter
Symbol
Test Condition
Min.
Typ.
Max.
Unit
Startup Current
IDDO
UVLHIGH Threshold
64
100
µA
Supply Current
IDD
No Load
1
2
4
mA
Startup Threshold
UVLHIGH
AS998
9
10
11
V
AS998A
9.5
10
10.5
V
UVL off Threshold
UVLLOW
7.6
8
8.4
V
Bias Current at POS
VCLAMP
IDD = 10mA No Load
13
14
14.7
V
Int Regulator Voltage
VREG
IREG = 1mA
5.5
6.25
7.0
V
Oscillator
Parameter
Symbol
Test Condition
Min.
Typ.
Max.
Unit
Mean Period
TOSC
8.4V < VDD<13.3V; 15 cycle avg. - AS998
7.3
9.3
11.7
µs
8.4V < VDD<13.3V; 15 cycle avg. - AS998A
8.1
9.3
10.7
µs
Modulation Repetition Rate
TREP
15
cycles
Peak-to-Peak Modulation
TDEV
Peak-to-Peak change in period
13.7
16.5
23
%
Max. Duty Cycle
DMAX
70
75
78
%
Error Amplifier
Parameter
Symbol
Test Condition
Min.
Typ.
Max.
Unit
FB Divider R
RFB
100
k
Ω
VDD Regulation Point
VDDREG
11.4
12
12.6
V
FB Threshold
VREF
COMP = FB, VDD = 12V
2.37
2.5
2.62
V
Gain (DC)
AVOL
No load on COMP
85
dB
Gain-Bandwidth Product
GBP
No load on COMP
10
MHz
COMP Output High
VCOMPH
FB = 2V
4.5
V
COMP Output Low
VCOMPL
FB = 3V
100
250
mV
COMP Source Current
ICOMPH
COMP = 3V, FB = 2V
25
50
100
µA
COMP Sink Current
ICOMPL
COMP = 1V, FB = 3V
25
300
500
µA
Current Sense Comparator
Parameter
Symbol
Test Condition
Min.
Typ.
Max.
Unit
Scaling of COMP
to CSNS input
0.4
AC Input Impedance
RCSAC
Fin
≥ FCO
100
k
Ω
Input Filter
FCS
Time Constant
320
ns
Prop. Delay to Output
tpd1
700
ns
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