isl6236a Intersil Corporation, isl6236a Datasheet - Page 19

• Manufacturer Part Number: isl6236a
• Description: High-efficiency, Quad-output, Main Power Supply Controllers For Notebook Computers
• Manufacturer: Intersil Corporation

Typical Performance Curves
Typical Application Circuits
The typical application circuits (Figures 66, 67 and ) generate
the 5V/7A, 3.3V/11A, 1.25V/5A, dynamic voltage/10A, 1.5V/5A,
1.05V/5A and external 14V charge pump main supplies in a
notebook computer. The ISL6236A is also equipped with a
secondary feedback, SECFB, used to monitor the output of the
14V charge pump. In an event when the 14V drops below its
threshold voltage, SECFB comparator will turn on LGATE1 for
300ns. This will refresh an external 14V charge pump without
overcharging the output voltage. The input supply range is
5.5V to 25V.
Detailed Description
The ISL6236A dual-buck, BiCMOS, switch-mode power-
supply controller generates logic supply voltages for
notebook computers. The ISL6236A is designed primarily for
battery-powered applications where high efficiency and low-
quiescent supply current are critical. The ISL6236A provides
FIGURE 63. LOAD TRANSIENT V
V
OUT1
LGATE1 5V/DIV
RIPPLE 50mV/DIV
IL1 5A/DIV
19
V
OUT2
OUT1
FIGURE 65. LOAD TRANSIENT V
RIPPLE 20mV/DIV
= 1.5V (SKIP)
Circuit of Figure 66, Figure 67, and Figure , no load on LDO, OUT1, OUT2, V
V
unless otherwise noted. Typical values are at T
IN
= 12V, EN2 = EN1 = VCC, V
V
OUT2
V
OUT1
LGATE2 5V/DIV
RIPPLE 20mV/DIV
ISL6236A
RIPPLE 20mV/DIV
a pin-selectable switching frequency, allowing operation for
200kHz/300kHz, 400kHz/300kHz, or 400kHz/500kHz on the
SMPSs.
Light-load efficiency is enhanced by automatic Idle-Mode
operation, a variable-frequency pulse-skipping mode that
reduces transition and gate-charge losses. Each step-down,
power-switching circuit consists of two N-Channel
MOSFETs, a rectifier, and an LC output filter. The output
voltage is the average AC voltage at the switching node,
which is regulated by changing the duty cycle of the
MOSFET switches. The gate-drive signal to the N-Channel
high-side MOSFET must exceed the battery voltage, and is
provided by a flying-capacitor boost circuit that uses a 100nF
capacitor connected to BOOT.
Both SMPS1 and SMPS2 PWM controllers consist of a
triple-mode feedback network and multiplexer, a multi-input
PWM comparator, high-side and low-side gate drivers and
OUT1
BYP
FIGURE 64. LOAD TRANSIENT V
= 1.05V (SKIP)
= 5V, PVCC = 5V, V
IL2 5A/DIV
A
V
= +25°C. (Continued)
OUT1
LGATE2 5V/DIV
IL1 5A/DIV
V
OUT2
RIPPLE 20mV/DIV
EN_LDO
RIPPLE 20mV/DIV
= 5V, T
OUT1
A
= -40°C to +100°C,
= 1.05V (PWM)
REF3
, and REF,
June 28, 2007
FN6453.1