UC3843ADR2 ON Semiconductor, UC3843ADR2 Datasheet - Page 10

• Manufacturer Part Number: UC3843ADR2
• Description: IC CTRLR CURRENT MODE HP 14SOIC
• Manufacturer: ON Semiconductor
• Type: High Performance Current Mode Controllersr

Specifications of UC3843ADR2

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 500kHz
• Duty Cycle: 96%
• Voltage - Supply: 8.2 V ~ 25 V
• Buck: No
• Boost: No
• Flyback: Yes
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: Yes
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Frequency-max: 500kHz
• Output Voltage Range: 4.9 V to 5.1 V
• Input Voltage Range: 30 V
• Operating Temperature Range: 0 C to + 70 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: UC3843ADR2OSTR

Undervoltage Lockout
incorporated to guarantee that the IC is fully functional
before the output stage is enabled. The positive power
supply terminal (V
each monitored by separate comparators. Each has built−in
hysteresis to prevent erratic output behavior as their
respective thresholds are crossed. The V
upper and lower thresholds are 16 V/10 V for the UCX842A,
and 8.4 V/7.6 V for the UCX843A. The V
upper and lower thresholds are 3.6V/3.4 V. The large
hysteresis and low startup current of the UCX842A makes
it ideally suited in off−line converter applications where
efficient bootstrap startup techniques are required
(Figure 34). The UCX843A is intended for lower voltage dc
to dc converter applications. A 36 V zener is connected as
a shunt regulator form V
protect the IC from excessive voltage that can occur during
system startup. The minimum operating voltage for the
UCX842A is 11 V and 8.2 V for the UCX843A.
Output
was specifically designed for direct drive of power
MOSFETs. It is capable of up to ±1.0 A peak drive current
PIN FUNCTION DESCRIPTION
Two undervoltage lockout comparators have been
These devices contain a single totem pole output stage that
8−Pin
1
2
3
4
5
6
7
8
−
−
−
−
Pin
2,4,6,13
14−Pin
10
12
14
11
1
3
5
7
−
8
9
CC
) and the reference output (V
Compensation
Current Sense
Power Ground
Feedback
Function
Voltage
CC
Output
R
GND
GND
V
V
NC
T
V
CC
/C
ref
C
to ground. Its purpose is to
T
UC3842A, UC3843A, UC2842A, UC2843A
This pin is Error Amplifier output and is made available for loop compensation.
This is the inverting input of the Error Amplifier. It is normally connected to the switching pow-
er supply output through a resistor divider.
A voltage proportional to inductor current is connected to this input. The PWM uses this infor-
mation to terminate the output switch conduction.
The Oscillator frequency and maximum Output duty cycle are programmed by connecting
resistor R
This pin is the combined control circuitry and power ground (8−pin package only).
This output directly drives the gate of a power MOSFET. Peak currents up to 1.0 A are
sourced and sunk by this pin.
This pin is the positive supply of the control IC.
This is the reference output. It provides charging current for capacitor C
resistor R
This pin is a separate power ground return (14−pin package only) that is connected back
to the power source. It is used to reduce the effects of switching transient noise on the control
circuitry.
The Output high state (V
With a separate power source connection, it can reduce the effects of switching transient
noise on the control circuitry.
This pin is the control circuitry ground return (14−pin package only) and is connected back to
the power source ground.
No connection (14−pin package only). These pins are not internally connected.
CC
ref
comparator
comparator
T
T
.
to V
ref
http://onsemi.com
ref
) are
and capacitor C
10
OH
) is set by the voltage applied to this pin (14−pin package only).
and has a typical rise and fall time of 50 ns with a 1.0 nF load.
Additional internal circuitry has been added to keep the
Output in a sinking mode whenever an undervoltage lockout
is active. This characteristic eliminates the need for an
external pull−down resistor.
pins for V
implementation will significantly reduce the level of
switching transient noise imposed on the control circuitry.
This becomes particularly useful when reducing the I
clamp level. The separate V
designer added flexibility in tailoring the drive voltage
independent of V
to this input when driving power MOSFETs in systems
where V
power and control ground connections in a current sensing
power MOSFET application.
Reference
tolerance at T
UC384XA. Its primary purpose is to supply charging current
to the oscillator timing capacitor. The reference has short
circuit protection and is capable of providing in excess of
20 mA for powering additional control system circuitry.
The SOIC−14 surface mount package provides separate
The 5.0 V bandgap reference is trimmed to ±1.0%
T
to ground. Operation to 500 kHz is possible.
CC
Description
C
is greater than 20 V. Figure 26 shows proper
(output supply) and Power Ground. Proper
J
= 25°C on the UC284XA, and ± 2.0% on the
CC
. A zener clamp is typically connected
C
supply input allows the
T
through
pk(max)