Hi Andy:
Thanks for your finding.
In GTA01, TX_MODEM and console_TX use the same UART port(S3C2410).
Therefore, R1519 use to reduce noise on console.
Now, I will remove R1519 in GTA02 because it's unused.
I will remove it to test the 2V on GSM VBAT.
Best Wishes
Allen Chang
-----Original Message-----
From: Andy Green [mailto:[EMAIL PROTECTED]
Sent: 2008/2/8 [星期五] 上午 12:33
To: ALLEN_CHANG (張吉隆)
Cc: [EMAIL PROTECTED]; [email protected]; TIM_LEE (李國平經理);
TONY_TU [塗能宇專案經理]; [EMAIL PROTECTED]; DKAY_CHEN [陳南廷]
Subject: Re: Suspended mode
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Somebody in the thread at some point said:
> Hi Andy:
>
>> Also check all the supply rails like V-DBB, V-IO, V-FLASH (hmm),
>> V_SRAM, V-SIM, V_RTC (hmm) and V-ABB to find ones that have >=1.8V
>> in suspend, then try to remove any pullup to these rails, eg, if
>> V-SIM has >= 1.8V, try to remove R1010 as a test.
>
> I power off GSM modem and set RX, TX, CTS, and RTS to output Low. The
> VBAT is 0.004. V-DBB, V-IO, V-FLASH,V-SRAM,V-SIM,V-RTC,and V-ABB are
> almost zero. I found total current is 4~5mA. It is better than before
> (8~9mA).
Hi Allen -
In my travels trying to understand another problem I came across R1519
on the CPU schematic -- it pulls TX_MODEM up by 10K to 3.3V.
Do we really need this? We can save <=330uA if the GSM stuff is powered
down by removing it. Hey it sounds like nothing but it is up to 6% of
that 5mA suspend current.
Plus it can be source of the 2V on GSM Vdd you were trying to track down?
- -Andy
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