10
10.6 UC3842/3
General description:
DESCRIPTION
TheUC3842/3/4/5family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency
current mode control schemes With a minimal external parts count. Internally implemented circuits include under voltage
lockout featuring start-up current less than 1 mA, a precision reference trimmed for accuracy at the error amp input, logic to
insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage
designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the off-
state. Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle
ranges. The UC3842 and UC3844 have UVLO thresholds of 16V (on) and 10V (off), ideally suited off-line applications The
corresponding thresholds for the UC3843 and UC3845 are 8.5 V and 7.9 V. The UC3842 and UC3843 can operate to duty
cycles approaching 100%. A range of the zero to < 50 % is obtained by the UC3844 and UC3845by the addition of an internal
toggle flip flop which blanks the output off every other clock cycle.
General Features
OPTIMIZED FOR OFF-LINE AND DC TO DC
CONVERTERS
LOWSTART-UP CURRENT (< 1 mA)
AUTOMATIC FEED FORWARD COMPENSA-TION
PULSE-BY-PULSECURRENT LIMITING
ENHANCED LOAD RESPONSE CHARAC-TERISTICS
UNDER-VOLTAGELOCKOUTWITHHYSTER-ESIS
DOUBLE PULSE SUPPRESSION
HIGH CURRENT TOTEMPOLE OUTPUT
INTERNALLY TRIMMED BANDGAP REFER-ENCE
500 KHz OPERATION
LOWRO ERRORAMP
PINNING
PIN VALUE
1. Comp
Compensation input
2. Vfb
Error amplifier input (Regulation)
3. I Sense
Over current protection voltage 1V typ.
4. Rt/Ct
Timing network
5. Ground
6. Output
MOSFET driver
7. Vcc
Supply voltage
8. Vref
+5V Reference output
10.7 E²Eprom 24CO8
General description:
The 24C08 is a 8Kbit electrically erasable programmable memory (EEPROM), organized as 4 blocks of 256 * 08 bits. The
memory operates with a power supply value as low as 2.5V.
Features:
Minimum 1 million ERASE/WRITE cycles with over 10 years data retention
Single supply voltage:4.5 to 5.5V
Two wire serial interface, fully I²C-bus compatible
Byte and Multi-byte write (up to 8 bytes)
Page write (up to 16 bytes)
Byte, random and sequential read modes
Self timed programming cycle
PINNING
PIN VALUE
1. Write protect enable
: 0V
2. Not connected
: 0V
3. Chip enable input
: 0V
4. Ground
: 0V
5. Serial data address input/output
: Input LOW voltage : Min : -0.3V, Max : 0.3*Vcc
: Input HIGH voltage : Min : 0.7*Vcc, Max : Vcc+1
6. Serial clock
: Input LOW voltage : Min : -0.3V, Max : 0.3*Vcc
: Input HIGH voltage : Min : 0.7*Vcc, Max : Vcc+1
7. Multibyte/Page write mode
: Input LOW voltage : Min : -0.3V, Max : 0.5V
: Input HIGH voltage : Min : Vcc-0.5, Max : Vcc+1
8. Supply voltage
: Min :2.5V, Max : 5.5V
