Datasheet

www.ti.com
(
)
10
DELAY
Delay Time 0.89 10 R sec
-
= · ·
1
delay T duty cycle
2
æ ö
= · -
ç ÷
è ø
t
DutyCycle
T
=
Period T=
DHL DHL
T (A to C) T (Bto D)= =
UC1879
UC2879
UC3879
SLUS230B – JUNE 1998 – REVISED JUNE 2007
ELECTRICAL CHARACTERISTICS (continued)
Unless specified; VC = VIN = V
UVSEL
= 12 V, CT = 470 pF, RT = 9.53k, R
DELSETA-B
= R
DELSEC-D
= 4.8k, C
DELSETA-B
= C
DELSETC-D
= 0.01 µ F, T
A
= T
J
.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Soft Start/Reset Delay
Charge current V
SS
= 0.5 V –20 –9 –3
µ A
Discharge current V
SS
= 1 V 120 230
Restart threshold 4.3 4.7 V
Discharge level 300 mV
Output Drivers
Output Low level I
OUT
= 10 mA 0.3 0.4
V
Output High level I
OUT
= –10 mA, Referenced to VC 2.2 3
Delay Set
(3)
Delay time
(4)
R
DELSETA-B
= R
DELSETC-D
= 4.8k 250 370 520
Delay time
(4)
R
DELSETA-B
= R
DELSETC-D
= 1.9k 100 155 220 ns
Zero delay
(5)
V
DELSETA-B
= V
DELSETC-D
= 5 V 5
(3) Delay time can be programmed via resistors from the delay set pins to ground.
The recommended range for R
DELAY
is 1.9 k Ω to 10 k Ω .
(4) Delay time is defined as:
where T is defined in Figure 1 .
(5) The zero phase shift voltage is the voltage measured at COMP which forces zero phase shift. This condition corresponds to zero
effective output power. Zero phase shift voltage has a temperature coefficient of about –2 mV/ ° C.
Figure 1. Phase Shift, Output Skew and Delay Time Definitions
6
Submit Documentation Feedback