TNY375-380
BYPASS/
DRAIN
(D)
MULTI-FUNCTION
(BP/M)
REGULATOR
5.85 V
LINE UNDER-VOLTAGE
115
A
25 A
FAULT
BYPASS PIN
PRESENT
UNDER-VOLTAGE
+
-
AUTO-
BYPASS
CAPACITOR
SELECT AND
CURRENT
RESTART
COUNTER
5.85 V
4.9 V
VILIMIT
RESET
LIMIT STATE
MACHINE
CURRENT LIMIT
COMPARATOR
-
ENABLE
1.0 V + VT
1.0 V
+
JITTER 2X
CLOCK
THERMAL
SHUTDOWN
DC
MAX
OSCILLATOR
S
R
Q
Q
ENABLE/
UNDER-
VOLTAGE
(EN/UV)
6.4 V
LEADING
EDGE
OVP
LATCH
BLANKING
RESET
SOURCE
(S)
PI-4550-121406
Figure 2
Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
P Package (DIP-8C)
G Package (SMD-8C)
D Package (SO-8C)
This pin is the power MOSFET drain connection. It provides
internal operating current for both start-up and steady-state
operation.
BYPASS/MULTI-FUNCTION (BP/M) Pin:
This pin has multiple functions:
1. It is the connection point for an external bypass capacitor for
the internally generated ꢀ.8ꢀ V supply.
2. It is a mode selector for the current limit value, depending on
the value of the capacitance added. Use of a 0.1 mF
capacitor results in the standard current limit value. Use of a
1 mF capacitor results in the current limit being reduced to
that of the next smaller device size. Use of a 10 mF capacitor
results in the current limit being increased to that of the next
larger device.
EN/UV
BP/M
S
S
1
2
8
7
6
5
S
S
4
D
PI-4348-042809
Figure 3. Pin Configuration.
3. It provides a shutdown function. When the current into the
bypass pin exceeds 7 mA, the device latches off until the
BP/M voltage drops below 4.9 V, during a power down or
when a line undervoltage is detected. This can be used to
provide an output overvoltage function with a Zener diode
connected from the BP/M pin to a bias winding supply.
ENABLE/UNDERVOLTAGE (EN/UV) Pin:
This pin has dual functions: enable input and line undervoltage
sense. During normal operation, switching of the power
MOSFET is controlled by this pin. MOSFET switching is
terminated when a current greater than a threshold current is
drawn from this pin. Switching resumes when the current being
2
Rev. C 09/12
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