Document
ST1843 ST1845
Rad-tolerant current mode PWM controller
Features
■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
Oscillator frequency guaranteed at 250 kHz Trimmed oscillator for precise frequency control Current mode operation to 500 kHz automatic feed forward compensation Latching PWM for cycle-by-cycle current limiting Internally trimmed reference with undervoltage lockout High current totem pole output Undervoltage lockout with hysteresis Low start-up and operating current Hermetic package 50 and 100 krad (Si) SEL free @ 120 MeV/cm2/mg at 125°C
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Flat-8
Description
The ST1843HR and ST1845HR ICs are radtolerant current mode PWM controllers providing an industry standard solution for the implementation of provides the off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Its radiation hardness and hermetic packaging makes it an ideal choice for aerospace and other harsh environments. Table 1. Device summary
Quality level Engineering Model EPPL Package Lead finish Mass (g) Flat-8 Flat-8 Flat-8 Flat-8 Gold Gold Gold Gold 0.45 0.45 0.45 0.45
Order codes Duty cycle max Radiation level ST1843K1 ST1843FKG ST1845K1 ST1845RKG 100% 100% 50% 50% 50 krad (Si) 50 krad (Si) 100 krad (Si) 100 krad (Si)
According to ESCC Target Engineering Model -
According to ESCC Target
September 2011
Doc ID 019049 Rev 1
1/25
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Datasheet pdf - http://www.DataSheet4U.co.kr/
Contents
ST1843 - ST1845
Contents
1 2 3 4 5 6 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Radiation characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1 Total dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1.1 6.1.2 6.1.3 Bias conditions and total dose level for total dose radiation testing . . . . . 9 Electrical measurements for total dose radiation testing . . . . . . . . . . . . 10 Heavy Ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7 8 9 10
Test circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
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Doc ID 019049 Rev 1
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ST1843 - ST1845
Block diagram
1
Block diagram
Figure 1.
9L
Block diagram (toggle flip flop used only in UC3844B and UC3845B)
9 89/2 65 9 5() ,17(51$/ %,$6 95()*22' /2*,&
*5281'
95() 9P$
9
7
57&7
287387
26& (5525$03 5 5 9
9)% &203 &855(17 6(16(
6 5 &855(17 6(16( &203$5$725
!-V
3:0 /$7&+
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Doc ID 019049 Rev 1
3/25
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Maximum ratings
ST1843 - ST1845
2
Maximum ratings
Table 2.
Symbol Vi IO EO
Absolute maximum ratings
Parameter Supply voltage (low impedance source) Supply voltage (Ii < 30mA) Output current Output energy (capacitive load) Analog inputs (pins 2, 3) Error amplifier output sink current Value 30 Self limiting ±1 5 – 0.3 to 5.5 10 800 – 65 to 150 – 40 to 150 A mJ V mA mW °C °C Unit V
Ptot Tstg TJ
Power dissipation at TA ≤ 25 °C (SO8) Storage temperature range Junction operating temperature
Note:
All voltages are with respect to pin 5, all currents are positive into the specified terminal.
3
Thermal data
Table 3.
Symbol RthJA
Thermal data
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Description Thermal resistance Junction-ambient. max.
Flat-8 100
Unit °C/W
4/25
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ST1843 - ST1845
Pin connection
4
Pin connection
Figure 2. Pin connection
',3 62
&203 9)% ,6(16( 57&7 95() 9L 287387 *5281'
!-V
Table 4.
No 1 2 3
Pin functions
Description This pin is the 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 power supply output through a resistor divider. A voltage proportional to inductor current is connected to this input. The PWM uses this information to terminate the output switch conduction. The oscillator frequency and maximum output duty cycle are programmed by connecting resistor RT to Vref and.