LNK584-586
BYPASS/
DRAIN
(D)
MULTI FUNCTION
(BP/M)
REGULATOR
5.85 V
OVERVOLTAGE
PROTECTION
+
-
PU
+
+
BYPASS PIN
UNDERVOLTAGE
GENERATOR
FEEDBACK REF
1.70 V
3 V
6.5 V
5.85 V
4.85 V
+
OPEN LOOP
PULL UP
FAULT
CURRENT LIMIT
FEEDBACK
(FB)
AUTO-RESTART
COUNTER
+
RESET JITTER
+
-
VILIMIT
0.9 V
S
R
Q
Q
CLOCK
DCMAX
ADJ
CC CUT BACK
1.70 V - 0.9 V
OSCILLATOR
SYSTEM
POWER
DOWN
LEADING
POWER
DOWN
COUNTER
160 fOSC
CYCLES
EDGE
BLANKING
PU
RESET
PI-5912-110910
SOURCE
(S)
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
The power MOSFET drain connection provides internal
operating current for both start-up, steady-state and Power-
Down mode operation.
G Package (SMD-8C)
D Package (SO-8C)
8
7
6
5
1
2
BP/M
FB
1
2
8
7
S
S
BP/M
FB
S
S
BYPASS/MULTI-FUNCTIONAL (BP/M) Pin:
An external bypass capacitor, 0.1 mF or greater for the internally
generated 5.85 V supply is connected to this pin. The minimum
value of capacitor is 0.1 mF for internal circuit operation. Higher
values may be required to enter Power-Down mode (see
LinkZero-AX Power-Down (PD) Mode Design Considerations).
An overvoltage protection disables MOSFET switching if the
current into the pin exceeds 6.5 mA (ISD).
S
S
6
5
S
S
4
D
4
D
3a
3b
PI-5910-090810
FEEDBACK (FB) Pin:
Figure 3. Pin Configuration.
During normal operation, switching of the power MOSFET is
controlled by this pin. MOSFET switching is disabled when a
voltage greater than an internal VFB reference voltage is applied
to this pin. The VFB reference voltage is internally set to 1.70 V.
LinkZero-AX goes into auto-restart mode when the FEEDBACK
pin voltage has come down to 0.9 V.
SOURCE (S) Pin:
This pin is the power MOSFET source connection. It is also the
ground reference for the BYPASS and FEEDBACK pins.
2
Rev. B 05/11
www.powerint.com
POWERINT [ Power Integrations ]
