PS10 SUTEX [Supertex, Inc], PS10 Datasheet - Page 6

• Manufacturer Part Number: PS10
• Description: Quad Power Sequencing Controller
• Manufacturer: SUTEX [Supertex, Inc]

Undervoltage/Overvoltage Operation
GND
UV
UV
OV
OV
PWRGD
Start-up Timing (PS11 PWRGD-A Active Low)
t
active. It can be approximated by
t
where
C
V
I
PWRGD-A
PWRGD-A
RAMP
RAMP
INT
OFF
ON
ON
OFF
= internal regulated power supply voltage (10V typ)
= 10 A charge current
Vin
= capacitor connected from RAMP pin to V
is the time delay from V
= C
RAMP
SET RESET
x (V
INT
-1.17)/I
RAMP
EEUV(on)
to PWRGD-A going
EE
pin
6
PWRGD Flags Delay Programming
When the ramp voltage hits Vint – 1.17V, PWRGD-A be-
comes active indicating that the input supply voltage is
within the programmed limits. PWRGD-B goes active after
a programmed time delay after PWRGD-A went active.
PWRGD-C goes active after a programmed time delay
after PWRGD-B went active. PWRGD-D goes active after
a programmed time delay after PWRGD-C went active.
The resistors connected from TB, TC, and TD to V
determines the delay times between the PWRGD flags.
The value of the resistors determines the capacitor charg-
ing and discharging current of a triangular wave oscillator.
The oscillator output is fed into an 8-bit counter to gener-
ate the desired time delay.
The respective time delay is defined by the following equa-
tion:
t
and
I
Where
t
C
V
I
Vbg = 1.17V (internal band gap reference)
R
Combining the two equations and solving for R
R
For a time delay of 200ms
R
For a time delay of 5ms
R
TX
CD
TX
CD
PP
OSC
TX
TX
TX
TX
= (255 x 2 x C
= Time delay between respective PWRGD flags
= Vbg / (4 x R
= Charge and discharge current of oscillator
= 8.2V (peak-to-peak voltage swing of oscillator)
= Programming resistor at TB, TC, or TD
= 120pF (internal oscillator capacitor)
= (Vbg x t
= 0.585 x 10
= 0.585 x 10
= 0.585 x 10
OSC
TX
TX
)
) / (2040 x C
x V
6
6
6
x t
x 0.2 = 117k
x 0.005 = 2.925k
PP
TX
)/I
CD
OSC
x V
PP
)
TX
yields:
A051204
EE
pin