ILE4263 Datasheet, PDF (7/10 Pages) IK Semicon Co., Ltd – Low-Drop Voltage Regulator

ILE4263
IC Operation Description
The typical IC application diagram is shown on the Figure 2.
The timing diagram of the Watchdog Function Reset (Watchdog function is not active) is
shown on the Figure 3.
The timing diagram of the active Watchdog Function is shown on the Figure 4.
Circuit Description
The error amplifier compares the reference voltage which is maintained with high precision re-
sistor adjustment with a voltage that is proportional to the output voltage, and drive the serial
transistor through the buffer. Saturation control, depending on the load current, prevents any
powerful element oversaturation. If externally scaled output voltage at the input reset threshold
RADJ falls below 1.35 V (typical valuation), then external delay reset discharge by the reset
generator. When the capacitor voltage reaches lower threshold U_DRL, at the output the reset signal
appears and held as long as the upper limit U_DU exceeded. If the reset threshold input RADJ is
connected to GND, then the reset is triggered at the output voltage of 4.65 V (typical valuation).
The connected microcontroller operation is monitored by Watchdog function. In the absence of
pulses on pin W, RO reset output is set to a low level. Reset delay time can be set in a wide range
by the reset delay capacitor. The IC can be switched on the inhibit input with active low level. The
IC also contains a number of internal circuits for overload and overtemperature protection, reverse
polarity protection.
Reset Timing
Power-up reset delay time is determined by the charge time of the external delay capacitor C_D,
nF, that can be calculated as follows
C_D = (t_rd × I_{D, ch}) / ΔV,
(1)
where t_rd – reset delay time, ms,
I_{D, ch} – charging current, uA (typical value 60 uA),
ΔV = V_DU – threshold RO output switching voltage to a high voltage state, V (typical value is
1.7 V).
Reset switching threshold
On default, installed typical value of reset switching threshold is 4.65 V. Using the ILE4263
the reset threshold can be set to 3.5 V < V_RT < 4.6 V by connection to RADJ external resistive
divider. Calculation is performed simplified as a reset input current adjustment may be neglected.
If this function is not required, the RADJ pin should be connected to GND. The threshold voltage of
output reset generator V_RT, V, is calculated by formula
V_RT = (1 + R1 / R2) × V_RADJTH,
(2)
where V_RADJTH – switching threshold voltage at the input reset adjustment ,V (typical value 1.35V).
2016 July, Ver.0