User Guide

PAMS
Technical Documentation
NSE–8/9
System Module
Page 2– 49
Issue 1 07/99
The power switch is controlled according to PWM input via V114a.
PSCC_PWM is supplied from the MAD and is different from the external
charge control PWM signal, which is supplied by the CCONT.
When PSCC_PWM is low, the switch is turned ON and the output current,
Iout, equals the charger current , except for the internal PSCC supply
consumption.
When PSCC_PWM is high, the switch is OFF and the output current is
zero or Istart , depending upon Vb. In MAD2PR1 power on / reset mode
PSCC_PWM is default high.
When Vb is below Vstart limit and it is needed to stop any charging
current (even Istart), e.g. when detecting external audio accessory, the
MAD can disable any charge current by commanding CTIM pin low via
V114b by setting CHARG_OFF signal high. The MAD pin controlling
V114b is low during power on / reset. The CHARGE_OFF signal always
takes precedence over PSCC_PWM, i.e. Istart is zero.
Table 22. PSCC characteristics
Parameter Symbol Min Typ Max Unit
Vb limit @ IStart cutoff Vstart 2.33 2.43 2.52 V
Start–up regulator output current
@Vb = 0V ... Vstart
Istart 150 180 210 mA
Charging current limitation Icharge 1.5 1.8 2.1 A
Vb Output voltage cutoff limit Vlim 3.32 3.46 3.6 V
Charger input voltage protection
limit
Vch 18 V
Vb threshold voltage to enter PWM
mode
Vpwm 1.9 2.0 2.1 V
PWM input logic control levels
Vil 0 0.7 V
Vih 1.8 2.85 V
Startup charging
When a charger is connected, the PSCC is supplying a startup current,
Istart to the battery.
Istart provides initial charging to the phone with an empty battery. The
PSCC charges the battery until Vb reaches the switcher start up voltage,
where the DC/DC converter powers up at it’s lowest output voltage level.
When Vdc_out reaches 3.0 V the CCONT powers up, recognizes charger
input, releases PURX reset signal and program execution starts.
If the current consumption is too high, Vb will drop below the switcher
shutdown limit, and it shuts down. The PSCC will continue charging with
Istart. Vb increases again and the power on sequence will repeat as
described until Vb and the energy content of the battery is sufficiently high
to support a full Baseband / MCU power on by the phone.
The MCU SW controls when the charging mode is changed from
startup–charging to PWM–charging (fast charging).