ML4819CP_NL Fairchild Semiconductor, ML4819CP_NL Datasheet - Page 5

• Manufacturer Part Number: ML4819CP_NL
• Manufacturer: Fairchild Semiconductor

Specifications of ML4819CP_NL

• Start-up Supply Current: 600uA
• Operating Supply Voltage (max): 35V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Package Type: PDIP
• Pin Count: 20
• Mounting: Through Hole
• Lead Free Status / RoHS Status: Compliant

ELECTRICAL CHARACTERISTICS
UNDER-VOLTAGE LOCKOUT
SUPPLY
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.
Note 2: V
Note 3: PWM comparator bias currents are subtracted from this reading.
FUNCTIONAL DESCRIPTION
OSCILLATOR
The ML4819 oscillator charges the external capacitor (C
with a current (I
voltage reaches the upper threshold, the comparator
changes state and the capacitor discharges to the lower
threshold through Q1. While the capacitor is discharging,
the clock provides a high pulse.
The oscillator period can be described by the following
relationship:
where:
and:
The maximum duty cycle of the PWM section can be
limited by setting a threshold on pin 7. when the C
is above the threshold at pin 7, the PWM output is held
off and the PWM flip-flop is set:
where:
REV. 1.0 10/10/2000
Start-Up Threshold
Shut-Down Threshold
V
Supply Current
REF
t
D
D
D
t
t
OSC
RAMP
Good Threshold
DEADTIME
LIMIT
OSC
LIMIT
CC
=
= t
is raised above the Start-Up Threshold first to activate the IC, then returned to 15V.
= Oscillator duty cycle
= Desired duty cycle limit
C(Ramp Valley to Peak)
RAMP
D
PARAMETER
C(Ramp Valley to Peak)
OSC
SET
+ t
) equal to 5/R
8.4mA - I
DEADTIME
(V
3.4
I
SET
PIN7
- 0.9)
SET
SET
. When the capacitor
Start-Up, V
Operating, T
(Continued)
T
ramp
CONDITIONS
CC
J
= 25 C
= 14V
T
)
+5V
DUTY CYCLE
RAMP VALLEY
Figure 1. Oscillator Block Diagram
RAMP PEAK
CLOCK
I
C
SET
R
MIN
T
T
15
9
10
20
7
C
5V
T
I
Q1
SET
TYP
8.4mA
4.4
0.6
16
10
25
t
V
D
REF
+
–
+
–
MAX
1.2
17
11
35
CLOCK
ML4819
UNITS
mA
mA
TO PWM
LATCH B
TO PWM
LATCHES
V
V
V
5